Air Traffic Control
FAA Needs to Ensure Better Coordination When Approving Air Traffic Control Systems Gao ID: GAO-05-11 November 17, 2004The Federal Aviation Administration's (FAA) process for ensuring that air traffic control (ATC) systems will operate safely in the national airspace system is an integral part of the agency's multibillion-dollar ATC modernization and safety effort. GAO was asked to review (1) FAA's process for approving ATC systems for safe use in the national airspace system; (2) challenges FAA has faced approving ATC systems and how these challenges affected the cost, schedule, and performance estimates of the systems; and (3) actions FAA has taken to improve its process for approving ATC systems.
FAA has separate processes for approving ground systems and certifying aircraft equipment for safe use in the national airspace system. FAA's process for approving ground systems, such as radar systems, is done in accordance with policies and procedures in FAA's Acquisition Management System. Approving ground systems, which are usually developed, owned, and operated by FAA, typically involves FAA's Air Traffic Organization determining whether a vendor is in compliance with contract requirements, followed by a rigorous test-and-evaluation process to ensure that the new system will operate safely in the national airspace system. The process for certifying aircraft equipment, which is usually developed by private companies, is done in accordance with Federal Aviation Regulations, with FAA serving as the regulator. If a system has both ground components and aircraft equipment components, then the system must go through both processes before it is approved for safe use in the national airspace system. FAA has faced challenges approving systems for safe use in the national airspace system that contributed to cost growth, delays, and performance shortfalls in deploying these systems. We identified three specific challenges through the review of 5 ATC systems and our past work. These challenges are the need to (1) involve appropriate stakeholders, such as users and technical experts, throughout the approval process; (2) ensure that the FAA offices that have responsibility for approving ground systems and certifying aircraft equipment effectively coordinate their efforts for integrated systems; and (3) accurately estimate the amount of time needed to meet complex technical requirements at the beginning of the design and development phase. FAA has taken some actions to address two of the three challenges we identified. However, FAA has not taken action to fully involve all stakeholders, such as air traffic controllers and technical experts, throughout the approval process. FAA officials believe that the agency's new Safety Management System will help ensure that the ground system approval and aircraft certification processes are better coordinated. FAA stated that coordination would improve because, as part of the new Safety Management System, the agency plans to realign its organizational structure to create a formal link between the Air Traffic Organization and the Office of Regulation and Certification. FAA expects full implementation of this system to take 3 to 5 years. We are reserving judgment on whether this change will fully address the challenge because of the early state of this effort and FAA's long-standing problems with internal coordination when approving ATC systems. As such, we believe that FAA should, in the interim, develop specific plans that describe how both internal and external coordination will occur on a system-specific basis.
RecommendationsOur recommendations from this work are listed below with a Contact for more information. Status will change from "In process" to "Open," "Closed - implemented," or "Closed - not implemented" based on our follow up work.
Director: Team: Phone:GAO-05-11, Air Traffic Control: FAA Needs to Ensure Better Coordination When Approving Air Traffic Control Systems
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Report to the Chairman, Subcommittee on Aviation, Committee on
Transportation and Infrastructure, House of Representatives:
November 2004:
AIR TRAFFIC CONTROL:
FAA Needs to Ensure Better Coordination When Approving Air Traffic
Control Systems:
[Hyperlink, http://www.gao.gov/cgi-bin/getrpt?GAO-05-11]:
GAO Highlights:
Highlights of GAO-05-11, a report to the Chairman, House Aviation
Subcommittee, Committee on Transportation and Infrastructure:
Why GAO Did This Study:
The Federal Aviation Administration‘s (FAA) process for ensuring that
air traffic control (ATC) systems will operate safely in the national
airspace system is an integral part of the agency‘s multibillion-dollar
ATC modernization and safety effort. GAO was asked to review (1) FAA‘s
process for approving ATC systems for safe use in the national airspace
system; (2) challenges FAA has faced approving ATC systems and how
these challenges affected the cost, schedule, and performance estimates
of the systems; and (3) actions FAA has taken to improve its process
for approving ATC systems.
What GAO Found:
FAA has separate processes for approving ground systems and certifying
aircraft equipment for safe use in the national airspace system. FAA‘s
process for approving ground systems, such as radar systems, is done in
accordance with policies and procedures in FAA‘s Acquisition Management
System. Approving ground systems, which are usually developed, owned,
and operated by FAA, typically involves FAA‘s Air Traffic Organization
determining whether a vendor is in compliance with contract
requirements, followed by a rigorous test-and-evaluation process to
ensure that the new system will operate safely in the national airspace
system. The process for certifying aircraft equipment, which is usually
developed by private companies, is done in accordance with Federal
Aviation Regulations, with FAA serving as the regulator. If a system
has both ground components and aircraft equipment components, then the
system must go through both processes before it is approved for safe
use in the national airspace system.
FAA has faced challenges approving systems for safe use in the national
airspace system that contributed to cost growth, delays, and
performance shortfalls in deploying these systems. We identified three
specific challenges through the review of 5 ATC systems and our past
work. These challenges are the need to (1) involve appropriate
stakeholders, such as users and technical experts, throughout the
approval process; (2) ensure that the FAA offices that have
responsibility for approving ground systems and certifying aircraft
equipment effectively coordinate their efforts for integrated systems;
and (3) accurately estimate the amount of time needed to meet complex
technical requirements at the beginning of the design and development
phase.
FAA has taken some actions to address two of the three challenges we
identified. However, FAA has not taken action to fully involve all
stakeholders, such as air traffic controllers and technical experts,
throughout the approval process. FAA officials believe that the
agency‘s new Safety Management System will help ensure that the ground
system approval and aircraft certification processes are better
coordinated. FAA stated that coordination would improve because, as
part of the new Safety Management System, the agency plans to realign
its organizational structure to create a formal link between the Air
Traffic Organization and the Office of Regulation and Certification.
FAA expects full implementation of this system to take 3 to 5 years.
We are reserving judgment on whether this change will fully address
the challenge because of the early state of this effort and FAA‘s long-
standing problems with internal coordination when approving ATC
systems. As such, we believe that FAA should, in the interim, develop
specific plans that describe how both internal and external
coordination will occur on a system-specific basis.
What GAO Recommends:
GAO is recommending that FAA develop ATC system-specific plans early in
the approval process that specify how and when the approving and
certifying offices within FAA and other stakeholders, including
controllers, maintenance technicians, technical experts, and industry
representatives, will meet to ensure coordination. FAA generally agreed
with the findings and recommendation in this report
www.gao.gov/cgi-bin/getrpt?GAO-05-11.
To view the full product, including the scope and methodology, click on
the link above. For more information, contact Katherine Siggerud at
(202) 512-2834 or siggerudk@gao.gov.
[End of section]
Contents:
Letter:
Results in Brief:
Background:
FAA Has Separate Processes for Approving Ground Systems and Certifying
Aircraft Equipment:
FAA Faced Challenges in Approving Several ATC Systems:
FAA Has Taken Action to Improve Its Process for Approving ATC Systems:
Conclusions:
Recommendation for Executive Action:
Agency Comments:
Appendixes:
Appendix I: Objectives, Scope, and Methodology:
Appendix II: Airport Surface Detection Equipment - Model X Case
Illustration:
Background:
Status:
FAA Faced Fewer Challenges in Approving ASDE-X:
Appendix III: Controller-Pilot Data Link Communications Case
Illustration:
Background:
Status:
Challenges in Approving CPDLC:
Appendix IV: Local Area Augmentation System Case Illustration:
Background:
Status:
FAA Faced Challenges in Approving LAAS:
Certification of LAAS Aircraft Equipment Has Been Affected by Delays in
Ground System Approval:
FAA's Aircraft Certification Office Needs to Coordinate Better with
Acquisition Offices:
Appendix V: Standard Terminal Automation Replacement System Case
Illustration:
Background:
Status:
FAA Faced Challenges in Approving STARS:
Appendix VI: Wide Area Augmentation System Case Illustration:
Background:
Status:
FAA Faced Challenges in Approving WAAS:
FAA Did Not Experience Major Challenges in Certifying the Aircraft
Equipment of WAAS:
Appendix VII: GAO Contacts and Staff Acknowledgments:
GAO Contacts:
Staff Acknowledgments:
Tables:
Table 1: FAA Systems Used as Case Illustrations:
Table 2: Cost and Schedule Estimate Changes to ASDE-X:
Table 3: ASDE-X Ground System Approval Timeline:
Table 4: Cost and Schedule Estimate Changes to CPDLC:
Table 5: CPDLC Ground System Approval Timeline (Build 1):
Table 6: CPDLC Ground System Approval Timeline (Build 1A):
Table 7: CPDLC Aircraft Equipment Certification Timeline:
Table 8: Cost and Schedule Estimate Changes to LAAS:
Table 9: LAAS Ground System Approval Timeline:
Table 10: LAAS Aircraft Equipment Certification Timeline:
Table 11: Cost and Schedule Estimate Changes to STARS:
Table 12: STARS Ground System Approval Timeline:
Table 13: Cost and Schedule Baseline Changes to WAAS:
Table 14: WAAS Ground System Approval Timeline:
Table 15: WAAS Aircraft Equipment Certification Timeline:
Figures:
Figure 1: Current FAA Offices with Responsibility for Approving Air
Traffic Control Systems:
Figure 2: Airport Surface Detection Equipment - Model X:
Figure 3: Controller-Pilot Data Link Communications:
Figure 4: LAAS Infrastructure:
Figure 5: Standard Terminal Automation Replacement System:
Figure 6: WAAS Architecture:
Abbreviations:
ASDE-X: Airport Surface Detection Equipment - Model X:
ATC: air traffic control:
CPDLC: Controller-Pilot Data Link Communications:
DOD: Department of Defense:
FAA: Federal Aviation Administration:
GPS: Global Positioning System:
LAAS: Local Area Augmentation System:
STARS: Standard Terminal Automation Replacement System:
WAAS: Wide Area Augmentation System:
Letter November 17, 2004:
The Honorable John L. Mica:
Chairman, Subcommittee on Aviation:
Committee on Transportation and Infrastructure:
House of Representatives:
Dear Mr. Chairman:
The Federal Aviation Administration's (FAA) process for ensuring that
air traffic control systems will operate safely in the national
airspace system is an integral part of FAA's multibillion-dollar air
traffic control modernization and safety effort. New air traffic
control systems cannot be used in the national airspace system until
FAA has determined that the systems will operate safely. Over the
years, FAA has approved about 45,000 pieces of air traffic control
equipment for safe use in the national airspace system. Some in the
aviation industry and government contend that FAA's approval process
for air traffic control systems is too lengthy and, therefore,
contributes to cost growth, schedule delays, and performance problems
that have plagued many of the systems that FAA has been trying to
develop for years. In addition, some in the aviation industry have
raised concerns about whether FAA's approval process has kept pace with
changes in technology. For example, more of today's new air traffic
control systems are integrated--that is, involving both ground
systems[Footnote 1] and equipment used exclusively in aircraft
(aircraft equipment) that must work together--than in the past.
In response to your request, we examined:
* FAA's process for approving air traffic control systems for safe use
in the national airspace system;
* challenges FAA faces in approving air traffic control systems and how
these challenges have affected the cost, schedule, and performance of
the systems; and:
* actions FAA has taken to improve its process for approving air
traffic control systems.
In this report, we use the word "approval" to describe the process of
ensuring the safety of an air traffic control system when it has both a
ground system and aircraft equipment. We also use the word "approval"
to describe the process of ensuring the safety of ground systems
exclusively. We use the word "certification" to describe the process of
ensuring the safety of aircraft equipment for safe use in the national
airspace system.
To identify FAA's process for approving air traffic control systems for
safe use in the national airspace system, we reviewed FAA documents
that describe the agency's process for approving such systems and
equipment and RTCA's 1999 and 2001 reports that also address this
process.[Footnote 2] To determine the challenges FAA has faced in
approving air traffic control systems and how these challenges affected
the cost, schedule, and performance of the systems, we (1) conducted
case illustrations on 5 of FAA's 25 air traffic control systems
currently receiving funding that were approved or in the process of
being approved for safe use in the national airspace system and (2)
reviewed reports prepared by GAO and the Department of Transportation's
Inspector General. The 5 air traffic control systems are:
* Airport Surface Detection Equipment - Model X (ASDE-X),
* Controller-Pilot Data Link Communications (CPDLC),
* Local Area Augmentation System (LAAS),
* Standard Terminal Automation Replacement System (STARS), and:
* Wide Area Augmentation System (WAAS).
We selected these 5 systems because collectively they accounted for
about 46 percent of FAA's air traffic control modernization costs in
fiscal year 2002 and 3 of the 5 systems are integrated--that is, they
require the approval of the ground systems as well as certification of
aircraft equipment before they can be used in the national airspace
system. In addition, we interviewed, among others, officials from FAA
program offices; RTCA; aviation industry groups; manufacturers of
aircraft equipment; ground system developers, including Honeywell,
Raytheon, and Sensis Corporation; industry experts; Wide Area
Augmentation System Integrity Performance Panel[Footnote 3] and Local
Area Augmentation System Integrity Panel members;[Footnote 4] and
unions representing air traffic controllers and maintenance
technicians. We also reviewed reports on air traffic control systems
prepared by GAO, the Department of Transportation's Inspector General,
RTCA, and the Commission on the Future of the U.S. Aerospace Industry
(Aerospace Commission). To identify what actions FAA has taken to
improve its processes for approving air traffic control systems, we
interviewed representatives from FAA, RTCA, the Aerospace Commission,
and aviation industry groups. See appendix I for additional information
on our objectives, scope, and methodology. We conducted our review from
October 2003 through September 2004 in accordance with generally
accepted government auditing standards.
Results in Brief:
FAA has separate processes for approving ground systems and certifying
aircraft equipment for safe use in the national airspace system. FAA's
process for approving ground systems, such as radar systems, is done in
accordance with policies and procedures in FAA's Acquisition Management
System. The process to approve ground systems, which are usually
developed, owned, and operated by FAA, involves FAA's Air Traffic
Organization determining whether a vendor is in compliance with
contract requirements and/or FAA operational requirements, followed by
a rigorous test-and-evaluation process to ensure that the new system
will operate safely in the national airspace system. In contrast,
federal aviation law requires that aircraft equipment, which is usually
developed by private companies, be certified in accordance with Federal
Aviation Regulations, with FAA serving as the regulator. Unlike the
approval of ground systems, which FAA accomplishes with the help of a
contractor, FAA is not typically involved in the development of the
equipment. An applicant, such as a manufacturer of aircraft equipment,
generally brings fully developed aircraft equipment to FAA for
certification. If an air traffic control system has both a ground
system and aircraft equipment, as was the case for 3 of the 5 systems
we reviewed, then the system must go through both processes before it
is approved for safe use in the national airspace system.
FAA has faced challenges in approving air traffic control systems for
safe use in the national airspace system. This report focuses on three
specific challenges we identified through our past work and our case
illustrations of 5 air traffic control systems. Most of these
challenges have made it more difficult for FAA to meet the systems'
cost, schedule, or performance estimates. These challenges are as
follows:
* Involving appropriate stakeholders, such as users and technical
experts, throughout the ground system approval process. For example,
during the design and development phase of the Standard Terminal
Automation Replacement System, which is designed to replace air traffic
controller workstations with new color displays, FAA did not involve
users such as air traffic controllers and maintenance technicians in
human factor evaluations, which examine how humans interact with
machines, because the aggressive development schedule limited the
amount of time available to involve them. Consequently, FAA and the
contractor later had to restructure the contract to address the
controllers' and technicians' concerns, such as the inconsistency of
visual warning alarms and color codes, which contributed to the system
being delayed by 3 years and a cost increase of $500 million.
* Ensuring that the FAA offices that have responsibility for approving
ground systems and certifying aircraft equipment effectively coordinate
their efforts for integrated systems. For example, although the Wide
Area Augmentation System was being developed by an integrated product
team that included representatives from various FAA offices, the team
did not function effectively in resolving issues related to meeting an
important functional requirement to alert the pilot in a timely manner
when the system should not be used because of a possible error.
According to FAA officials, the reason coordination was not effective
was because the two offices had competing priorities that were not
associated with development of the Wide Area Augmentation System. This
ineffective coordination, combined with other factors, contributed to a
6-year delay in commissioning the Wide Area Augmentation System and a
$1.5 billion increase in its development costs.
* Accurately estimating the amount of time needed to meet complex
requirements at the beginning of the design and development phase. For
example, FAA accelerated the schedule for the Standard Terminal
Automation Replacement System in 1995. This acceleration in schedule
left only limited time for human factor evaluations and, according to
FAA officials, added $500 million to the Standard Terminal Automation
Replacement System's cost and 3 years to the schedule because the
agency had to revise its strategy for acquiring and approving it.
FAA has taken actions to address two of the three challenges we
identified. However, FAA has not taken action to fully involve all
stakeholders, such as air traffic controllers, maintenance technicians,
technical experts, and industry representatives, throughout the
approval process. To ensure that the two offices effectively coordinate
their ground system approval and aircraft equipment certification
processes, FAA officials believe that the agency's new Safety
Management System, which is designed to formalize and standardize the
agency's safety process, will improve overall coordination among FAA
stakeholders once the system is implemented. FAA stated that
coordination would improve because, as part of the new Safety
Management System, the agency plans to realign its organizational
structure to create a formal link between the Air Traffic Organization,
which currently approves ground systems, and the Office of Regulation
and Certification. FAA expects full implementation of this system to
take 3 to 5 years. We are reserving judgment on whether this change
will fully address the challenge because of the early state of this
effort and because FAA's problems with internal coordination when
approving air traffic control systems are long-standing. In addition,
because FAA has historically faced internal and external coordination
challenges in approving air traffic control systems for safe use in the
national airspace system, we believe that as FAA moves forward with
implementing the agency's new Safety Management System, it should, in
the interim, develop plans that describe:
how both internal and external coordination will occur on a system-
specific basis. In addition, plans to include external stakeholders are
particularly important since the Safety Management System is not
intended to address this challenge.
We are recommending that FAA develop early in the approval process air
traffic control system-specific plans that specify how and when the
approving and certifying offices within FAA and other stakeholders,
including controllers, maintenance technicians, technical experts, and
industry representatives, will meet to ensure coordination.
Background:
Several offices within FAA's Air Traffic Organization and Office of
Regulation and Certification have responsibility for approving ground
systems and certifying aircraft equipment, as shown in figure 1.
Figure 1: Current FAA Offices with Responsibility for Approving Air
Traffic Control Systems:
[See PDF for image]
Note: The Office of Regulation and Certification's Air Traffic Safety
Oversight Service oversees and collaborates with the Air Traffic
Organization's Safety Services on the safety of air traffic control
systems.
[End of figure]
Before the creation of the Air Traffic Organization in November 2003,
FAA's Research and Acquisitions (acquisitions office) and Air Traffic
Services were the primary offices responsible for approving ground
systems for safe use in the national airspace system. The 5 systems
that we reviewed began the approval process under that structure.
Currently, these offices, although renamed, form the core of the Air
Traffic Organization. The responsibilities of Air Traffic Services are
now distributed among several offices, including System Operations
Services and Terminal Services. The responsibilities of Research and
Acquisitions are distributed among several offices, including Technical
Operations Services and En Route and Oceanic Services. In addition, the
Air Traffic Organization includes Safety Services, which is its focal
point for safety, quality assurance, and quality control and is the
primary interface with FAA's Office of Regulation and Certification.
FAA's Office of Regulation and Certification has responsibility for
certifying and regulating aircraft and its equipment. The following 3
offices within the Office of Regulation and Certification are involved
in the certification of aircraft equipment:
* Aircraft Certification Service (aircraft certification office) is
responsible for administering safety standards for aircraft and
aircraft equipment that are manufactured in the United States.
* Flight Standards Service is responsible for granting operational
approval to air carriers that plan to use equipment on their aircraft.
* Air Traffic Safety Oversight Service is responsible for monitoring
the safety of air traffic operations through the establishment,
approval, and acceptance of safety standards and the monitoring of
safety performance and trends. It will also improve coordination
between the Office of Regulation and Certification and the Air Traffic
Organization.
In addition to the internal FAA stakeholders, the approval of air
traffic control (ATC) systems can also involve a number of other
external stakeholders. FAA generally makes the decision about which
other stakeholders will be involved in approving ATC systems for safe
use in the national airspace system. For example, stakeholders involved
in approving ATC systems may include:
* technical experts;
* ground system developers;
* manufacturers of aircraft equipment;
* aviation industry groups;
* general aviation; and:
* users, such as controllers and maintenance technicians.
FAA also regularly requests RTCA, a private, not-for-profit
corporation, to develop consensus-based performance standards for the
aircraft equipment component of ATC systems. RTCA functions as a
federal advisory committee that provides recommendations used by FAA as
the basis for policy, program, and regulatory decisions and by the
private sector as the basis for development, investment, and other
business decisions.
In this report, we focus on the approval of the 5 ATC systems described
in table 1 and further discussed in appendixes II through VI.
Table 1: FAA Systems Used as Case Illustrations:
System: Airport Surface Detection Equipment - Model X (ASDE-X);
Description: ASDE-X is a traffic management system that air traffic
controllers use to track aircraft and vehicle movement at an airport.
ASDE-X was developed to prevent runway accidents. It also provides
aircraft identification from an airport's surface. ASDE-X uses a
combination of surface movement radar and sensors to display aircraft
position on an ATC tower display. The integration of these sensors
provides accurate, up-to-date, and reliable data to improve airport
safety in all weather conditions.
System: Controller-Pilot Data Link Communications (CPDLC);
Description: CPDLC allows pilots and controllers to transmit digital
messages directly between an FAA ground automation system and suitably
equipped aircraft. CPDLC is a new way for controllers and pilots to
communicate that is analogous to e-mail. This system is meant to
alleviate voice congestion problems and increase controller
efficiency.
System: Local Area Augmentation System (LAAS);
Description: LAAS is a precision approach and landing system that
relies on the Global Positioning System (GPS) to broadcast highly
accurate information to aircraft on the final phases of a flight. LAAS
is being developed specifically to augment GPS satellites to support
precision approaches and landing capability to aircraft operating
within a 20-to 30-mile radius of the airport. LAAS approaches will be
designed to avoid obstacles, restricted airspace, noise-sensitive
areas, or congested airspace.
System: Standard Terminal Automation Replacement System (STARS);
Description: STARS replaces controller workstations with new color
displays, processors, and computer software at the FAA and the
Department of Defense terminal ATC facilities. FAA's goal for STARS is
to provide an open, expandable terminal automation platform that can
accommodate future air traffic growth and allow for the introduction of
new hardware-and software-based tools to promote safety, maximize
operational efficiency, and improve controllers' productivity.
System: Wide Area Augmentation System (WAAS);
Description: WAAS is a GPS-based navigation and landing system that is
meant to improve safety by providing precision guidance to aircraft for
all phases of flight at thousands of airports and landing strips where
there is no ground-based landing capability. WAAS consists of 25 ground
reference stations, 2 leased geostationary satellites, 2 master
stations, and 4 uplink stations. The ground reference stations are
strategically positioned across the United States to collect GPS
satellite data. WAAS is designed to improve the accuracy, integrity,
and availability of information coming from GPS satellites and to
correct signal errors caused by solar storms, timing, and satellite
errors. Unlike conventional ground-based navigation aids, WAAS provides
curved precision approach paths in order to avoid obstacles, restricted
airspace, noise-sensitive areas, and congested airspace.
Source: FAA.
[End of table]
FAA Has Separate Processes for Approving Ground Systems and Certifying
Aircraft Equipment:
FAA has separate processes for approving ground systems and certifying
aircraft equipment for safe use in the national airspace system. FAA's
process for approving ground systems, such as radar systems, is done in
accordance with policies and procedures in FAA's Acquisition Management
System.[Footnote 5] This process involves a determination by FAA's Air
Traffic Organization regarding whether a vendor is in compliance with
contract requirements and/or FAA operational requirements, followed by
a rigorous test-and-evaluation process to ensure that the new system
will operate safely in the national airspace system. In contrast, the
process for certifying aircraft equipment, which is usually developed
by private companies, is done in accordance with Federal Aviation
Regulations, with FAA serving as the regulator. If an ATC system has
both a ground system and aircraft equipment, as was the case for 3 of
the 5 systems we reviewed, then the system must go through both
processes before it is approved for safe use in the national airspace
system.
Ground System Approval Process:
The approval of a ground system focuses on safety and is done in
accordance with FAA contract documents and policies and procedures that
are part of the agency's Acquisition Management System. Most ground
systems that provide air traffic services and air navigation services
are developed, owned, and operated by FAA. Prior to November 2003,
FAA's Research and Acquisitions and Air Traffic Service offices were
responsible for the approval of ground systems. Currently, FAA's Air
Traffic Organization has primary responsibility for the approval of
ground systems. FAA's ground system approval process includes the
following six phases--concept of operations, requirements setting,
design and development, test and evaluation, operational readiness,
commissioning--and involves various stakeholders, which are also noted
below.
* Concept of operations: The ground system approval process begins with
the concept of operations phase. If the system being developed has both
a ground system and aircraft equipment, FAA's Office of Regulation and
Certification, Air Traffic Services Office, and Acquisitions Office
may work together to develop the concept of operations.[Footnote 6]
During this phase, FAA generally identifies and defines a service or
capability to meet a particular need in the national airspace system
and may involve other stakeholders, such as air traffic
controllers.[Footnote 7] FAA also defines the roles and
responsibilities of key participants, such as controllers and
maintenance technicians, and the key elements of the required
capability. The concept of operations phase is not a static process. As
FAA obtains more information about the system it develops, the concept
is revised to reflect the new information even though the next phase of
the process may have already begun. Potential stakeholders in this
phase include FAA's Office of Regulation and Certification, FAA's Air
Traffic Organization, aircraft manufacturers, aviation industry
associations, airlines, air traffic controllers, maintenance
technicians, manufacturers of aircraft equipment, ground system
developers, and representatives of general aviation.
* Requirements setting: During the requirements-setting phase, FAA
establishes a minimum set of requirements, including safety objectives,
and specifies how well the new system must perform its intended
functions. For example, it was during this phase that FAA established
WAAS' and LAAS' integrity requirement--which is that the system cannot
fail to warn pilots of misleading information that could potentially
create hazardous situations more than once in 10 million approaches.
After analyzing the initial requirements and comparing the cost,
benefits, schedule, and risk of various solutions, FAA sets final
requirements and presents them to the Joint Resources Council as part
of the investment plan.[Footnote 8] After the council has approved the
requirements for the new system, FAA will issue a request for
proposals, evaluate the offers received, and select a contractor to
design a system based on the requirements set by FAA. Potential
stakeholders in this phase include FAA's Office of Regulation and
Certification, FAA's Air Traffic Organization, aircraft manufacturers,
aviation industry associations, airlines, air traffic controllers,
maintenance technicians, manufacturers of aircraft equipment, ground
system developers, and representatives of general aviation.
* Design and development: The design and development of ground systems
is generally completed by a contractor and monitored by FAA. During
this phase, the contractor conducts preliminary and critical design
reviews, which include plans for how it will conduct the testing phase.
FAA must approve these plans before the contractor can proceed to the
next phase. Potential stakeholders in this phase include FAA, ground
system developers, air traffic controllers, and maintenance
technicians.
* Test and evaluation: After FAA has approved the design and
development of the system, it is ready to be tested and evaluated. The
testing and evaluation of ground systems typically includes three major
tests: development tests, operational tests, and an independent
operational test and evaluation. Development testing is performed by
the contractor to verify compliance with contractual requirements and
is overseen by FAA. Operational testing is performed by FAA and is
designed to demonstrate that a new system is operationally effective
and suitable for use in the national airspace system. An independent
operational test and evaluation is a full system-level evaluation
conducted by FAA in an operational environment to confirm the
operational readiness of a system to be part of the national airspace
system. Potential stakeholders in this phase include FAA, ground system
developers, air traffic controllers, and maintenance technicians.
* Operational readiness: During the operational readiness phase, FAA
personnel are trained to operate and maintain the new system, usually
in conjunction with its predecessor system. Following operational
readiness approval, the system is ready to be commissioned. Potential
stakeholders in this phase include FAA, ground system developers, air
traffic controllers, and maintenance technicians.
* Commissioning: The commissioning phase ensures that the new ground
system as installed meets the intended mission and operational
requirements and is fully supported by the national airspace system
infrastructure. Potential stakeholders in this phase include FAA,
ground system developers, air traffic controllers, and maintenance
technicians.
Aircraft Equipment Certification Process:
In contrast to the ground system approval process, certification of
aircraft equipment is done in accordance with procedures outlined in
the Federal Aviation Regulations, Title 14, Code of Federal
Regulations, Part 21. Under Title 49, Section 44704, of the U.S. Code,
FAA has the authority to issue type certificates, supplemental type
certificates, and production certificates, among others, for aircraft
and equipment that will be used in the national airspace
system.[Footnote 9] Unlike the approval of ground systems, which FAA
accomplishes with the help of a contractor, FAA is the regulator of
aircraft equipment and is not typically involved in the development of
the equipment. An applicant, such as a manufacturer of aircraft
equipment, generally brings fully developed aircraft equipment to FAA
for certification. The aircraft equipment certification process
includes the following five phases--concept of operations, requirements
setting, design and production approval, installation approval, and
operational approval--and involves several stakeholders, which are also
noted below:
* Concept of operations: Like the ground system approval process, the
aircraft equipment certification process generally begins with the
concept of operations phase, when the aircraft equipment is part of an
ATC system. If the aircraft equipment certification process is not
associated with the approval of a new ground system, then the
certification process may begin with an idea for better equipment.
During this phase, FAA, sometimes with the help of industry, identifies
and defines a service or capability to meet a particular need in the
national airspace system.[Footnote 10] Potential stakeholders in this
phase include FAA's Office of Regulation and Certification, FAA's Air
Traffic Organization, aircraft manufacturers, aviation industry
associations, airlines, air traffic controllers, maintenance
technicians, manufacturers of aircraft equipment, ground system
developers, and representatives of general aviation.
* Requirements setting: Once FAA has identified the need for a new
system with aircraft equipment, FAA determines the requirements for:
the aircraft equipment.[Footnote 11] In some cases, the requirements
for aircraft equipment may already exist in the Federal Aviation
Regulations. In other cases, FAA may ask RTCA to develop the
requirements, including safety requirements, which are referred to as
minimum operating performance standards. RTCA typically takes 1 to 5
years to develop the standards because of the need to reach consensus
between FAA and the industry and the increasing complexity of systems
being developed today. According to a RTCA official, the time required
to develop recommended standards is a function of many variables,
including urgency of the situation and the commitment and availability
of government and industry volunteers to collaboratively develop the
standards. For example, in the case of WAAS, RTCA began setting
performance standards in 1994, completed the original version of the
standards in January 1996, and completed the most recent version of
WAAS performance standards in November 2001. Potential stakeholders in
this phase include FAA's Office of Regulation and Certification, FAA's
Air Traffic Organization, aircraft manufacturers, aviation industry
associations, airlines, air traffic controllers, maintenance
technicians, manufacturers of aircraft equipment, ground system
developers, and representatives of general aviation.
* Design and production approval: The requirements/performance
standards, most often developed by RTCA, typically form the basis for a
technical standard order, which FAA uses to grant design and production
approval for most new aircraft equipment developed in support of
national airspace system modernization efforts. Technical standard
orders are FAA's requirements for materials, parts, processes, and
appliances used on civil aircraft.[Footnote 12] Most aircraft
manufacturers want technical standard orders because they make
installation approval simpler and less costly and allow for operation
in any type of aircraft. Technical standard orders are issued for items
ranging from safety belts to navigation equipment. If the applicant
successfully completes the design and production approval phase, FAA
provides the applicant with a technical standard order authorization
letter, which states that the applicant has met a specific technical
standard order and the product is now ready for the installation
approval phase. Potential stakeholders in this phase include FAA's
Aircraft Certification Service, manufacturers of aircraft equipment,
and aircraft manufacturers.
* Installation approval: After receiving a technical standard order
authorization for new aircraft equipment, the initial applicant must
receive installation approval from FAA before the aircraft equipment
may be used in the national airspace system. To receive installation
approval, the applicant submits a certification plan and test plan to
one of FAA's aircraft certification offices for review and approval. In
addition, the applicant conducts ground and flight tests under FAA's
supervision to ensure that the new equipment operates properly upon
installation. Once the tests are completed to FAA's satisfaction, FAA
issues a supplemental type certificate, which is evidence of FAA's
approval to modify an aircraft from its original design. Potential
stakeholders in this phase include FAA's Aircraft Certification
Service, manufacturers of aircraft equipment, and aircraft
manufacturers.
* Operational approval: Finally, for the aircraft equipment to become
certified for use in the national airspace system by air carrier
operators, operational approval is also needed from FAA. To obtain
operational approval, the applicant must successfully demonstrate,
among other things, that the pilots are properly trained to use the
aircraft equipment and that maintenance personnel are properly trained
to maintain the equipment. Potential stakeholders in this phase include
FAA's Flight Standards Service, airlines, and representatives of
general aviation.
FAA Faced Challenges in Approving Several ATC Systems:
FAA faced challenges in approving systems for safe use in the national
airspace system that contributed to cost growth, delays, and
performance shortfalls in deploying these systems. We identified three
specific challenges through the review of 5 ATC systems and our past
work.[Footnote 13] These challenges are the need to:
* involve appropriate stakeholders, such as users and technical
experts, throughout the approval process;
* ensure that the FAA offices that have responsibility for approving
ground systems and certifying aircraft equipment effectively coordinate
their efforts for integrated systems; and:
* accurately estimate the amount of time needed to meet complex
technical requirements at the beginning of the design and development
phase.
Although most of the challenges we found relate to the ground system
approval process, RTCA and the Aerospace Commission have identified
challenges with FAA's aircraft equipment certification process. For
example, RTCA found that there was a need for better internal FAA
communication and coordination, including the establishment of an
organizational focal point to provide coordinated responses to all
matters related to ground systems and aircraft equipment. In addition,
the Aerospace Commission found that FAA's regulatory process needs to
be streamlined to enable the timely development of regulations needed
to address new technologies.
FAA Did Not Always Adequately Involve Appropriate Stakeholders, Such as
Users and Technical Experts, Throughout Its Approval Process:
FAA failed to adequately involve appropriate stakeholders, such as air
traffic controllers and maintenance technicians, for 3 of the 5 systems
we reviewed. For example, FAA did not adequately involve controllers
and maintenance technicians throughout the approval process of STARS,
which will replace controller workstations with new color displays,
processors, and computer software. Although controllers and technicians
were involved in developing requirements for STARS in 1994 prior to the
1996 contract award to Raytheon, the original approved acquisition plan
provided for only limited human factors evaluation by controllers and
technicians during STARS' design and development because the aggressive
development schedule limited the amount of time available to involve
them.[Footnote 14] Consequently, FAA and Raytheon had to restructure
the contract to address controllers' concerns that were identified
later, such as the inconsistency of visual warning alarms and color
codes with the new system. According to FAA officials, not involving
controllers and maintenance technicians in the design phase caused the
agency to revise its strategy for acquiring and approving STARS, which
contributed to STARS' overall cost growth of $500 million and added 3
years to the schedule.
FAA also did not always sufficiently involve technical experts early in
its approval process for 2 additional systems that we reviewed. For
example, FAA did not obtain technical expertise on how to resolve the
integrity requirement of WAAS, a navigation system for aviation that
augments the Global Positioning System (GPS), until late in the design
and development phase.[Footnote 15] FAA acknowledges that the agency's
in-house technical expertise was not sufficient to address the
technical challenges of WAAS. Initially, FAA and the contractor
believed they could meet the WAAS integrity requirement to alert the
pilot in a timely manner when the system should not be used. However,
although WAAS was being developed by an integrated product team that
included representatives from several FAA offices, the team did not
function effectively in resolving issues related to meeting an
important functional requirement to alert the pilot in a timely manner
when the system should not be used because of a possible error.
According to FAA officials, the reason coordination did not occur was
that the two offices had competing priorities that were not associated
with WAAS' development. Consequently, in 2000, FAA convened the WAAS
Integrity Performance Panel to help it meet the integrity requirement.
The WAAS Integrity Panel worked for about 2-1/2 years before it came up
with a solution to the integrity requirement. In addition, in August
2000, the agency established an Independent Review Board, which is
independent of the panel and included experts in satellite navigation
and safety certification, to oversee the panel and evaluate the
soundness of its efforts. According to a member of the WAAS Integrity
Panel, if FAA had involved these technical groups immediately after the
contract was awarded to Raytheon in 1996, these groups could have
started devising a solution in 1996, rather than in 2000. This lack of
technical expertise contributed to a 6-year delay in WAAS'
commissioning and a $1.5 billion increase in its development costs from
the 1994 baseline.[Footnote 16]
FAA also did not fully engage technical experts early in the approval
process of LAAS, a precision approach and landing system that will
augment GPS. According to FAA officials, meeting the LAAS integrity
requirement to alert the pilot in a timely manner when the system
should not be used is perhaps the most difficult part of approving this
system for safe use in the national airspace system. According to the
Department of Transportation's Inspector General, although FAA had a
LAAS Integrity Panel in place since 1996 to assist with its research
and development activities, the panel was not formally tasked with
resolving LAAS' integrity issues. According to one satellite navigation
expert and the Department of Transportation's Inspector General,
focusing the LAAS Integrity Panel on resolving the integrity
requirement early in the approval process may have enabled FAA to
develop a quicker solution.[Footnote 17] In 2003, FAA focused the LAAS
Integrity Panel on developing a solution to meet the integrity
requirement. However, FAA and another satellite expert maintain that
the technical complexity of this problem is the main reason that LAAS
is not commissioned. According to FAA officials, the need to validate
integrity requirements and further software development has resulted in
FAA placing LAAS in its research and development program and suspending
funding for fiscal year 2005.
In contrast, FAA faced fewer schedule and cost problems in approving
ASDE-X for use in the national airspace system. This was, in part,
because FAA included stakeholders early and throughout the approval
process and because program managers had strong technical expertise.
The ASDE-X program office brought in stakeholders, including
maintenance technicians and air traffic controllers, during the concept
of operations phase and continued to involve them during requirements
setting, design and development, and test and evaluation. FAA also
brought ASDE-X stakeholders together at technical meetings to provide
input on ASDE-X design and development, which allowed the ASDE-X
program office to design a system that met requirements and
incorporated stakeholders' needs. By obtaining the input of controllers
and technicians at the beginning of the approval process, FAA was able
to ensure that ASDE-X requirements were set at appropriate levels and
not overspecified or underspecified. Some stakeholders commented that
the program managers' strong technical expertise was one reason that
ASDE-X's requirements were set appropriately. As a result, this system
was initially commissioned only 5 months behind schedule and its cost
increased moderately from $424 million to $510 million.
FAA Did Not Always Effectively Coordinate Its Certification and
Approval Processes:
FAA did not always effectively coordinate its certification and
approval processes for CPDLC, WAAS, and LAAS. Coordination between
FAA's offices responsible for approval of ground systems and
certification of aircraft equipment is becoming increasingly important
given that more and more ATC systems have both ground systems and
aircraft equipment. However, we found that coordination was not
effective on CPDLC Build 1A, which allows pilots and controllers to
transmit digital data messages directly between FAA ground automation
systems and suitably equipped aircraft.[Footnote 18] In the interest of
meeting the original cost and schedule estimates, FAA awarded the
contract before it had a full understanding of system requirements.
Requirements that specify how the ground system and aircraft equipment
would operate together were not yet completed prior to award of the
Build 1A contract. Consequently, changes needed to be made after the
contract was awarded. New hardware requirements, software requirements,
and other system requirement changes were added, which increased
CPDLC's costs by $41 million, almost 61 percent of the total cost
increases associated with CPDLC.
The lack of effective coordination among FAA offices responsible for
approving WAAS also contributed to delays and increased costs in
commissioning WAAS. Although WAAS was being developed by an integrated
product team that included representatives from various FAA offices,
the team did not function effectively in resolving issues related to
meeting an important functional requirement to alert the pilot in a
timely manner when the system should not be used because of a possible
error. According to FAA officials, the reason coordination was not
effective was because the two offices had competing priorities that
were not associated with development of WAAS. Consequently, it was not
until September 1999, when the aircraft certification office became
fully involved, that FAA recognized that its solution to meet WAAS'
integrity requirement was not sufficient and that it did not have the
technical expertise needed to develop a solution. This lack of
coordination contributed to a 6-year delay in WAAS' commissioning and a
$1.5 billion increase in its development costs.
LAAS is another example of how FAA did not effectively coordinate its
efforts. For example, FAA's Office of Regulation and Certification
completed the design and production approval of LAAS aircraft equipment
without effectively coordinating with the offices responsible for
acquisition to determine the consequences of certifying aircraft
equipment before approval of the associated ground system. According to
an FAA official, once the Office of Regulation and Certification has
given design and production approval to the LAAS aircraft equipment, it
is not possible to make a change to the requirements for the aircraft
equipment so that they are better integrated with the associated LAAS
ground system. Consequently, LAAS ground system developers may have to
make more costly and time-consuming changes to the ground system than
would have been necessary if the Office of Regulation and Certification
and acquisitions offices had coordinated their efforts.
FAA Did Not Always Prepare Accurate Estimates of the Amount of Time
Needed to Meet Complex Technical Requirements:
We have reported in the past that when FAA attempts to combine
different phases of system development in an effort to more quickly
implement the systems to meet milestones, it repeatedly experiences
major performance shortfalls and rework, which leads to schedule delays
and cost increases.[Footnote 19] We found that WAAS, STARS, and LAAS
all experienced delays and cost increases in part because FAA did not
prepare accurate estimates of the amount of time needed to meet complex
technical requirements, leading to an accelerated schedule that
sometimes failed to include activities such as human factors
evaluations and technical expert consultations. For example, in 1994,
in response to the concerns of government and aviation groups, FAA
accelerated implementation of WAAS milestones from 2000 to 1997. FAA
planned to develop, test, and deploy WAAS within 28 months, an
unrealistic goal given that software development alone was expected to
take 24 to 28 months. It was not until July 2003, over 6 years later,
that FAA was able to commission WAAS for initial operating capability.
The accelerated schedule contributed to the 6-year delay in the
commissioning of the system because the schedule itself was unrealistic
and additional design work needed to be completed. During that time,
the cost to develop the system increased about $1.5 billion, and the
system has yet to meet its original performance goal of providing
pilots with the ability to navigate down to 200 feet during their
approach to the runway.
FAA also accelerated the schedule for STARS in 1995. FAA's approach to
commissioning STARS was oriented to rapid deployment to meet critical
needs for new equipment. To meet these needs, FAA compressed its
original development and testing schedule from 32 to 25 months.
Consequently, this acceleration in schedule left only limited time for
human factors evaluations and, according to FAA officials, contributed
to STARS' overall cost growth of $500 million and added 3 years to the
first deployment because the agency had to revise its strategy for
acquiring and approving STARS.
Although FAA had not developed a solution for meeting the integrity
requirement, FAA also accelerated the LAAS schedule in 1999 by setting
system milestones before completely designing the system. FAA
originally planned to deploy LAAS in 2002 but has since moved it to
fiscal year 2009 because the system's software development is not
complete and a solution for meeting LAAS' integrity requirements has
yet to be developed.
RTCA and the Aerospace Commission Found Challenges with FAA's Process
for Approving Ground Systems and Certifying Aircraft Equipment:
RTCA and the Aerospace Commission also identified challenges with FAA's
process for approving ground systems and certifying aircraft equipment.
In 1998, at the request of the FAA Administrator, RTCA reviewed FAA's
certification/approval process to determine if it could be made more
responsive to the changing state of aviation, including its more
integrated technologies. RTCA found that FAA's ground system approval
process and aircraft equipment certification process took too long and
cost too much, and RTCA made several recommendations to improve the
processes. For example, in 2001, RTCA recommended that FAA implement a
coordinated approval process that, among other things, would ensure
that all stakeholders, including those outside FAA's program offices,
participate in all phases of the approval process. Specifically,
similar to our finding that the FAA offices that had responsibility for
approving ground systems and certifying aircraft equipment did not
always effectively coordinate their efforts, RTCA found that there was
a need for better internal FAA communication and coordination,
including the establishment of an organizational focal point to provide
coordinated responses to all matters related to ground systems and
aircraft equipment. RTCA also found that there was a need for an
earlier and better exchange of information between FAA and those
involved in the approval and certification processes from outside FAA,
such as manufacturers of aircraft equipment.[Footnote 20]
In 2000, Congress asked the Commission on the Future of the U.S.
Aerospace Industry to study the health of the aerospace industry and
identify actions that the United States needs to take to ensure the
industry's health. As part of this study, the Aerospace Commission
reviewed FAA's certification process for aircraft equipment and made
recommendations. The Aerospace Commission found that FAA's
certification of new aircraft technologies has become uncertain in
terms of time and cost and recommended that FAA's regulatory process be
streamlined to enable the timely development of regulations needed to
address new technologies. According to the Aerospace Commission,
instead of focusing on rules and regulations that dictate the design
and approval of equipment, FAA should focus on certifying that
manufacturing organizations have safety built into their processes for
designing, testing, and ensuring the performance of an overall system.
The commission believed that such an approach would allow FAA personnel
to better keep up with technological progress by becoming less design-
specific and more safety-focused.
FAA Has Taken Action to Improve Its Process for Approving ATC Systems:
FAA has taken action to address two of the three management challenges
that we identified. However, FAA has not taken action to ensure that
all stakeholders, such as air traffic controllers, maintenance
technicians, technical experts, and industry representatives, are
involved throughout the ground system approval process. FAA has also
taken some action to address recommendations made by RTCA and the
Aerospace Commission. Examples of some of the actions FAA has taken
that address the management challenges that we found as well as RTCA
and Aerospace Commission recommendations are discussed below:
* Coordinating FAA's acquisitions offices and Office of Regulation and
Certification efforts for approving systems with ground and aircraft
components: FAA officials believe that the agency's new Safety
Management System, which is designed to formalize the agency's safety
process, will also improve coordination among FAA internal stakeholders
once it is implemented. FAA stated that coordination would improve
because as part of the new Safety Management System the agency plans to
realign its organizational structure to create a formal link between
the Air Traffic Organization and the Office of Regulation and
Certification. Within the Office of Regulation and Certification, there
is the newly created Air Traffic Safety Oversight Service, which
oversees the safety operations of the Air Traffic Organization and
collaborates with the Air Traffic Organization's Safety Services. In
addition, according to FAA officials, both ground systems and aircraft
equipment will be more consistently assessed for their effect on safety
as safety terminology is standardized. FAA expects full implementation
to take 3 to 5 years. We are reserving judgment on whether this change
will fully address the challenge because of the early state of this
effort and because FAA's problems with internal coordination when
approving ATC systems are long-standing. In addition, because FAA has
historically faced internal and external coordination challenges in
approving ATC systems for safe use in the national airspace, we believe
that as FAA moves forward with the agency's new Safety Management
System, it should, in the interim, develop plans that describe how both
internal and external coordination will occur on a system-specific
basis. In addition, plans to include external stakeholders are
particularly important since the Safety Management System is not
intended to address this challenge.
* Estimating the amount of time needed to meet complex technical
requirements: During the development of WAAS and STARS, FAA adopted an
incremental approach to developing and testing these systems to get
them back on track, which is referred to as the "build a little, test a
little" or spiral development approach. For example, to get WAAS back
on track, FAA decided to take a more incremental approach to
implementing the new navigation system--focusing more on the successful
completion of research and development before starting system approval.
In particular, FAA allowed time for collecting and evaluating data on
key system performance requirements like the WAAS integrity requirement
before moving forward. FAA officials acknowledged that the manner in
which FAA decided to implement WAAS development before implementing
this incremental approach was a high-risk approach and was a primary
issue underlying the system's problems. Some aviation stakeholders
believe this approach is advantageous because, although it can increase
costs initially, money can be saved in the long run because the
approach may help to avoid mistakes that are very costly to fix once a
system has been developed. This approach also helps to ensure that the
necessary building blocks of a system are tested along the way through
the early and ongoing involvement of key stakeholders, those who will
use and maintain the system. These stakeholders are key to identifying
critical omissions and issues that could prevent a system from
operating as intended.[Footnote 21]
As previously discussed, RTCA and the Aerospace Commission reviewed
FAA's approval process and made a number of recommendations to improve
it. FAA has taken some action to address these recommendations. For
example:
* In response to RTCA's recommendation to implement a process in which
the regulators and applicants come to an early and clear agreement on
their respective roles, responsibilities, expectations, schedules, and
standards to be used in certification projects, FAA issued The FAA and
Industry Guide to Avionics Approval in 2001, which is intended to help
FAA reduce the time and cost for the certification of aircraft
equipment. This guide describes how to plan, manage, and document an
effective, efficient aircraft equipment certification process and how
to develop a working relationship between FAA and the applicant. In
addition, as part of the 1999 FAA and Industry Guide to Product
Certification, FAA encourages the manufacturers of aircraft equipment
to develop a Partnership for Safety Plan that defines roles and
responsibilities, describes how the certification process will be
conducted, and identifies the milestones for completing the
certification. A WAAS aircraft equipment manufacturer said that the
certification of the WAAS aircraft equipment it developed went
smoothly, primarily because of this up-front agreement with FAA.
Although FAA's actions address the aircraft equipment certification
process, it does not have a similar process for its ground system
approval process.
* In response to RTCA's recommendation to establish an organizational
focal point to provide one-stop service to users, industry, and other
governments in all matters related to advanced ground electronics and
aircraft equipment, FAA has completed a Web site that provides a broad
range of information on the certification process for aircraft
equipment. However, there is still no focal point to which industry can
address questions about the approval process and be assured of getting
a fully coordinated FAA answer.
* In response to the Aerospace Commission's recommendation to
streamline its aircraft equipment certification process to ensure
timely development of regulations needed to address new technologies
and to focus on certifying that manufacturing organizations have built
safety into their processes for designing, testing, and ensuring the
performance of an overall system, FAA proposed creating an
Organizational Designation Authorization program in January 2004. The
program would expand the approval functions of FAA organizational
designees,[Footnote 22] standardize these functions to increase
efficiency, and expand eligibility for organizational designees.
Conclusions:
FAA did not always include stakeholders throughout the process for
approving ATC systems for safe use in the national airspace system.
Including stakeholders is particularly important because the new ATC
systems are more integrated today than in the past and thus require
more coordination among all the stakeholders, particularly FAA's Office
of Regulation and Certification and the recently created Air Traffic
Organization, but also between FAA and other stakeholders, such as
technical experts, controllers, and maintenance technicians. When
decisions regarding integrated ATC systems are made in isolation, they
may contribute to the ineffective use of resources and time. We found
that 3 of the 5 ATC systems we reviewed experienced cost growth and
schedule delays, in part, because FAA did not always involve all
necessary stakeholders, such as controllers and technical experts,
throughout the approval process. In 2001, RTCA recommended that FAA
implement a coordinated approval process that, among other things,
would ensure that all stakeholders, including those outside FAA's
program offices, participate in all phases of the approval process. We
agree with RTCA's recommendation, which FAA has not fully implemented,
and believe that fully implementing it would help address some of the
challenges we found with FAA's approval and certification processes.
In addition, although FAA's new Safety Management System and the
planned alignment between FAA's Air Traffic Organization and Office of
Regulation and Certification have the potential to improve FAA's
internal coordination, FAA has just begun implementing these
initiatives with full implementation 3 to 5 years away. FAA also has
historically faced internal coordination challenges in approving ATC
systems for safe use in the national airspace system as we found for
each of the 3 integrated systems that we reviewed. We believe that the
implementation of the Safety Management System, coupled with the new
formal link between FAA's Air Traffic Organization and Office of
Regulation and Certification, will give FAA the opportunity to improve
its internal coordination among its offices that are responsible for
ground system approval and aircraft equipment certification. However,
the system will not be implemented until 3 to 5 years. Therefore,
because of FAA's history of internal and external coordination
challenges, such as the lack of effective coordination between FAA
offices responsible for approving WAAS, which contributed to WAAS' cost
increase of about $1.5 billion and schedule delays of 6 years, we
believe that specific plans for improving coordination both internally
and externally on a system-specific basis are needed now.
Recommendation for Executive Action:
To ensure that key stakeholders, such as air traffic controllers,
maintenance technicians, and technical experts, outside FAA's
acquisitions offices and Office of Regulation and Certification, are
involved early and throughout FAA's ground system approval process and
to ensure better internal coordination between FAA's offices
responsible for approving ground systems and certifying aircraft
equipment, we recommend that the Secretary of Transportation direct the
Administrator of FAA to develop ATC system-specific plans early in the
approval process that specify how and when the approving and certifying
offices within FAA and other stakeholders, including controllers,
maintenance technicians, technical experts, and industry
representatives, will meet to ensure coordination.
Agency Comments:
We provided a draft of this report to the Secretary of Transportation
for review and comment. FAA generally agreed with our findings and
recommendation and provided technical corrections, which we
incorporated as appropriate. FAA also commented that it has started to
take actions to improve its coordination efforts for integrated ATC
systems.
We are sending copies of this report to interested congressional
committees, the Secretary of Transportation, and the FAA Administrator.
We will also make copies available to others on request. In addition,
the report will be available at no charge on the GAO Web site at
[Hyperlink, http://www.gao.gov]. Should you or your staff have
questions on matters discussed in this report, please contact me on
(202) 512-2834 or at [Hyperlink, siggerudk@gao.gov]. GAO contacts and
key contributors to this report are listed in appendix VII.
Sincerely yours,
Signed by:
Katherine Siggerud:
Director, Physical Infrastructure Issues:
[End of section]
Appendixes:
Appendix I: Objectives, Scope, and Methodology:
To complete our first objective, to describe FAA's process for
approving air traffic control (ATC) systems for safe use in the
national airspace system, we obtained and analyzed documents from the
Federal Aviation Administration (FAA) and RTCA's[Footnote 23] 1999
report that discussed FAA's process for certifying aircraft equipment
and approving ground systems. We also interviewed FAA officials,
contractors, industry experts, and unions representing air traffic
controllers and maintenance technicians that are involved in approving
ATC systems.
To complete our second objective, to describe the challenges FAA has
faced approving ATC systems and how those challenges affected the cost,
schedule, and performance estimates of the systems, we conducted case
illustrations on 5 of FAA's 25 air traffic control systems that are
currently receiving funding:
* Airport Surface Detection Equipment - Model X (ASDE-X),
* Controller-Pilot Data Link Communications (CPDLC),
* Local Area Augmentation System (LAAS),
* Standard Terminal Automation Replacement System (STARS), and:
* Wide Area Augmentation System (WAAS).
We selected these 5 systems because collectively they accounted for
about 46 percent of FAA's ATC modernization costs in fiscal year 2002
and 3 of the 5 systems are integrated--that is, they require the
approval of the ground systems as well as aircraft equipment. To select
the 5 case illustration systems, we used FAA's capital investment
project data file. We met with knowledgeable FAA officials to discuss
issues related to the accuracy and completeness of the data file, which
was deemed adequate for the purpose of our work. We also met with
knowledgeable FAA officials to determine the number of ATC systems from
the data file that needed to be approved before entry into the national
airspace system. For each of the case illustrations, we reviewed FAA
documents, including acquisition program baseline reports, Joint
Resource Council decisions, and briefing documents. We also reviewed
GAO and Department of Transportation's Inspector General reports and
testimonies. In addition, we interviewed officials from FAA program
offices; RTCA; the General Aviation Manufacturers Association; the Air
Transport Association; the Aircraft Owners and Pilots Association;
NavCanada; Transport Canada; the MITRE Corporation; Boeing; Garmin;
Rockwell Collins; contractors, including Honeywell, Raytheon, and the
Sensis Corporation; industry experts; the WAAS Integrity Performance
Panel; the LAAS Integrity Panel members; and unions representing air
traffic controllers and maintenance technicians.
To compete our third objective, to describe actions FAA has taken to
improve its processes for approving ATC systems, we interviewed
representatives from FAA; RTCA; the Commission on the Future of the
U.S. Aerospace Industry; aviation industry groups, including the
General Aviation Manufacturers Association, the Air Transport
Association, and the Aircraft Owners and Pilots Association;
manufacturers of aircraft equipment, including Garmin and Rockwell
Collins; Boeing; and contractors, including Honeywell, Raytheon, and
the Sensis Corporation; industry experts; and unions representing air
traffic controllers and maintenance technicians.
We conducted our review in Washington, D.C., from October 2003 through
September 2004 in accordance with generally accepted government
auditing standards.
[End of section]
Appendix II: Airport Surface Detection Equipment - Model X Case
Illustration:
Background:
ASDE-X is an airport surface surveillance system that air traffic
controllers use to track aircraft and vehicle surface movements. (See
fig. 2.) ASDE-X uses a combination of surface movement primary radar
and multilateration[Footnote 24] sensors to display aircraft position
and vehicle position on an ATC tower display. According to FAA, the
integration of these sensors provides accurate, up-to-date, and
reliable data for improving airport safety in all weather conditions.
ASDE-X was developed to prevent accidents resulting from runway
incursions,[Footnote 25] which have increased since 1993. The number of
reported runway incursions rose from 186 in 1993 to 383 in 2001.
According to FAA, because air traffic in the United States is expected
to double by 2010, runway incursions may pose a significant safety
threat to U.S. aviation.
FAA expects that ASDE-X will increase the level of safety at airports
and provide air traffic controllers with detailed information about
aircraft locations and movement at night and in bad weather due to the
(1) association of flight plan information with aircraft position on
controller displays; (2) continuous surveillance coverage of the
airport from arrival through departure; (3) elimination of blind spots
and coverage gaps; and (4) availability of surveillance data with an
accuracy and update rate suitable for, among other things, awareness in
all weather conditions.
Figure 2: Airport Surface Detection Equipment - Model X:
[See PDF for image]
[End of figure]
Status:
In October 2003, FAA commissioned ASDE-X at Mitchell International
Airport in Milwaukee, Wisconsin, for use in the national airspace
system. ASDE-X came in close to its original schedule and cost
baselines. The ASDE-X system was approximately 5 months over its
original schedule baseline, but maintained its original performance
baselines. In June 2002, FAA approved $80.9 million in additional
funding to add ASDE-X at 7 additional sites. (See table 2.) FAA is
currently scheduled to deploy ASDE-X at 25 U.S. airports over the next
4 years and to update existing surface detection systems (i.e., ASDE-3)
at 9 other facilities. FAA plans to introduce an upgraded ASDE-X system
at T.F. Green Airport in Providence, Rhode Island, with deployment
tentatively slated for the 4th quarter of 2004. FAA is also
investigating whether to add ASDE-X at 25 airports that use ASDE-3 and
Airport Movement Area Safety Systems.
Table 2: Cost and Schedule Estimate Changes to ASDE-X:
Dollars in millions;
September 2001 (baseline);
Estimated development costs: $424.3[A];
Initial operating capability: May 2003;
Full operating capability: 2007.
June 2002 (upgrade);
Estimated development costs: $80.9[B];
Initial operating capability: September 2004;
Full operating capability: 2005.
October 2003 (in-service decision);
Estimated development costs: $510.2[C];
Initial operating capability: October 2003;
Full operating capability: 2007[D].
Source: GAO presentation of FAA data.
[A] Includes 25 operational ASDE-X sites, 4 support systems, and 1
ASDE-3 upgrade.
[B] Includes 7 ASDE-3 site upgrades.
[C] The October 2003 cost estimate includes a $5 million congressional
addition for Dulles Airport.
[D] Although the last approved baseline included the 2007 date for last
deployment, internal and external reprogramming for other high-priority
activities and budget decrements in fiscal years 2004 and 2005 will
slip the last deployment to fiscal year 2009. The ASDE-X program office
is preparing a baseline management notice to adjust the baseline.
[End of table]
FAA Faced Fewer Challenges in Approving ASDE-X:
Of the five systems we reviewed, FAA faced fewer schedule and cost
challenges in approving ASDE-X for safe use in the national airspace
system. This is partly because FAA included stakeholders early and
throughout the approval process and because of the strong technical
expertise of its managers. The ASDE-X program office brought in
stakeholders, including maintenance technicians and air traffic
controllers, beginning with the concept of operations phase and
continued their stakeholder involvement through the requirements-
setting, design-and-development, and test-and-evaluation phases and
then continued involvement throughout the deployment phase. For
example, FAA obtained the input of controllers and technicians at the
beginning of the approval process, which helped to ensure that ASDE-X
requirements were set at appropriate levels and not overspecified or
underspecified. Stakeholders pointed toward the strong technical
expertise of the program's managers as a reason for the appropriate
specification of ASDE-X's requirements. In addition, FAA brought ASDE-
X stakeholders together at technical meetings to provide input on ASDE-
X design and development, which allowed the ASDE-X program office to
design a system that met requirements and incorporated stakeholders'
needs.
However, FAA did experience some challenges in approving ASDE-X. In
response to Congress' desire to deploy the system quickly, FAA
attempted to accelerate ASDE-X's approval. However, FAA experienced
problems in accelerating the approval when it awarded the contract
before all requirements had been finalized.
Table 3 shows the major phases and time frames associated with the
ASDE-X approval process.
Table 3: ASDE-X Ground System Approval Timeline:
Phase: Concept of operations;
Date: May 1998.
Phase: Requirements setting: Final requirements document;
Date: September 1999.
Phase: Requirements setting: Contract award (signed);
Date: November 2000.
Phase: Design and development: Planned human factors requirements;
Date: February 2001.
Phase: Design and development: Critical design review;
Date: April 2001.
Phase: Design and development: Baseline change;
Date: June 2002.
Phase: Design and development: Underdeveloped radars;
Date: July 2002.
Phase: Test and evaluation: Development test;
Date: March 2003.
Phase: Test and evaluation: Operational test and evaluation;
Date: May 2003.
Phase: Test and evaluation: Independent operational test and
evaluation;
Date: August 2003.
Phase: Operational readiness;
Date: October 2003.
Phase: Commissioning;
Date: October 2003.
Source: GAO presentation of FAA data.
[End of table]
[End of section]
Appendix III: Controller-Pilot Data Link Communications Case
Illustration:
Background:
CPDLC will allow pilots and controllers to transmit digital data
messages directly between FAA ground automation computers and suitably
equipped aircraft. (See fig. 3.) CPDLC is a new way for controllers and
pilots to communicate that is analogous to e-mail. The pilot can read
the message displayed on a screen in the cockpit and respond to the
message with the push of a key. In the future, this will alleviate
frequency congestion problems and increase controller efficiency. One
of the most important aspects of this technology is its intended
reduction of operational errors from misunderstood instructions and
readback errors. The initial phase (Build 1) consisted of four
services: initial contact, altimeter[Footnote 26] setting, transfer of
communication, and predefined instructions via menu text. The CPDLC
program will ultimately develop additional capabilities in an
incremental manner through further development stages. Originally,
Build 1 was to be followed by Build 1A, which was designed to increase
the CPDLC message set and include assignment of speeds, headings, and
altitudes as well as a route clearance function.
Figure 3: Controller-Pilot Data Link Communications:
[See PDF for image]
[End of figure]
Status:
CPDLC was commissioned for initial daily use by controllers at Miami on
October 7, 2002. This completed the stage called Build 1, which
included four services. American Airlines is the CPDLC launch airline
with about 25 aircraft operating in the Miami Center airspace. Further
deployment of CPDLC has been deferred until about 2009 after the Joint
Resources Council did not approve the program in April 2003. The
council made this decision because it believed that the benefits of
CPDLC did not outweigh the costs. A number of factors contributed to
this decision. First, FAA had concerns about how quickly aircraft would
install the new airborne equipment. Second, the approved program
baseline was no longer valid as Build 1A investment costs had increased
from $114.5 million to $181.7 million, while the number of locations
decreased from 20 to 8 as shown in table 4. Third, CPDLC would add $83
million to the operations account.
Table 4: Cost and Schedule Estimate Changes to CPDLC:
Dollars in millions;
Baseline/Cost estimate year: 1999 (Build 1A);
Estimated development costs[A]: $114.5;
Initial operational capacity - Build 1: June 2002;
Initial operational capacity - Build 1A: June 2005;
Locations (after Build 1A-completion): 20.
Baseline/Cost estimate year: April 2003[B];
Estimated development costs[A]: $181.7;
Initial operational capacity - Build 1: October 2002;
Initial operational capacity - Build 1A: Undetermined;
Locations (after Build 1A-completion): 8.
Source: GAO presentation of FAA data.
[A] CPDLC Build 1 costs were $52.2 million.
[B] FAA did not approve this cost estimate.
[End of table]
For fiscal year 2005, program officials requested $3 million for CPDLC.
According to FAA, this amount would be suitable for shutdown of CPDLC
at Miami, closeout of Build 1, and alternatives analysis for a follow-
on program. The contractor, ARINC, had been providing messaging service
for Miami at no cost. However, the contract for this free service
expired on June 30, 2004.
Challenges in Approving CPDLC:
Lack of full coordination between FAA's aircraft certification and
acquisition offices, in which there would have been a full
understanding of all requirements, compromised the schedule and cost of
CPDLC. FAA's acquisitions office, in the interest of meeting the
original cost and schedule estimates, awarded the contract before FAA
had a full understanding of system requirements, including those of
FAA's aircraft certification office. Requirements that specified in
detail how the air and ground equipment would operate together were not
yet completed prior to award of the Build 1A contract. The addition of
CPDLC hardware and software requirements increased costs by $26
million, 39 percent of CPDLC's Build 1A development cost growth. In
addition, other system requirement changes after contract award
increased CPDLC's baseline development cost estimate by another $15
million. In total, these requirement additions increased costs by $41
million, almost 61 percent of the total cost increases associated with
CPDLC Build 1A. (See tables 5, 6, and 7 for timelines of CPDLC's ground
system approval and aircraft equipment certification.)
Table 5: CPDLC Ground System Approval Timeline (Build 1):
Phase: Concept of operations (initial);
Date: October 1991.
Phase: Requirements setting: Final requirements document;
Date: October 1998;
revised April 2003.
Phase: Requirements setting: Contract award;
Date: January 1999.
Phase: Design and development: Critical design review;
Date: September 2000.
Phase: Test and evaluation: Development test;
Date: February 2002.
Phase: Test and evaluation: Operational test;
Date: December 2001.
Phase: Test and evaluation: Independent operational test and
evaluation;
Date: Early assessment - March 2003.
Phase: Test and evaluation: Initial operating capability;
Date: October 2002.
Phase: Operational readiness;
Date: October 2002.
Phase: Commissioning (Build 1);
Date: October 2002.
Source: GAO presentation of FAA data.
[End of table]
Table 6: CPDLC Ground System Approval Timeline (Build 1A):
Phase: Concept of operations (initial);
Date: October 1991.
Phase: Requirements setting: Final requirements document;
Date: November 2002.
Phase: Requirements setting: Investment analysis[A];
Date: July 2003.
Source: GAO presentation of FAA data.
[A] Program has been deferred since completion of the investment
analysis.
[End of table]
Table 7: CPDLC Aircraft Equipment Certification Timeline:
Phase: Concept of operations (initial);
Date: October 1991.
Phase: Requirements setting: Certification plan (American Airlines);
Date: August 2000.
Phase: Design and production approval;
Date: May 2001.
Phase: Installation approval;
Date: May 2001.
Phase: Operational approval;
Date: September 2002.
Source: GAO presentation of FAA data.
[End of table]
[End of section]
Appendix IV: Local Area Augmentation System Case Illustration:
Background:
LAAS is a precision approach and landing system that will augment the
Global Positioning System (GPS)[Footnote 27] to broadcast highly
accurate information to aircraft on the final phases of a flight. LAAS
is being developed specifically to provide augmentation to GPS
satellites to support Category I, II, and III precision approach and
landing capability[Footnote 28] to aircraft operating within a 20-to
30-mile radius of an airport. LAAS approaches are to be designed to
avoid obstacles, restricted airspace, noise-sensitive areas, or
congested airspace. In addition, a single LAAS ground station is to be
capable of providing precision approach capability to multiple runways.
LAAS has both ground and air components. LAAS ground components include
four or more GPS reference receivers, which monitor and track GPS
signals; very high frequency transmitters for broadcasting the LAAS
signal to aircraft; and ground station equipment, which generates
precision approach data and is housed at or near an airport. (See fig.
4.) LAAS users will have to purchase aircraft equipment to take
advantage of the system's benefits.
Figure 4: LAAS Infrastructure:
[See PDF for image]
[End of figure]
Status:
FAA's fiscal year 2005 budget request eliminated funding for LAAS,
which is being moved from the acquisition program into a research and
development effort. LAAS was slated for a 2006 rollout, but the target
has now been deferred until at least 2009. FAA officials said they will
reconsider national deployment when more research results are
completed.
Before FAA decided to suspend funding for LAAS in fiscal year 2005, the
LAAS program office was negotiating with Honeywell to develop a plan
for determining how to meet the integrity requirements for the LAAS
Category I system. According to FAA officials, the LAAS program office
will use the $18 million remaining in fiscal year 2004 to continue the
LAAS Integrity Panel for developing the LAAS Category I system, to
validate LAAS Category II/III requirements, and to solve radio
frequency interference issues. The $18 million will last through 2005,
and FAA's goal is to meet LAAS integrity requirement by September 2005.
Because of the budget cuts in fiscal year 2005, the LAAS program office
will not be developing a Category II/III prototype.
As shown in table 8, the LAAS Category I system was initially expected
to be operational in 2002. However, FAA was unable to meet the
milestone, primarily due to development and integrity requirement
issues. According to FAA officials, the research needed to validate the
integrity requirement of LAAS Category I is scheduled to be completed
by September 2005. If funds are fully restored in fiscal year 2005, FAA
officials said that a LAAS Category I system can be developed and
deployed by fiscal year 2009.
Table 8: Cost and Schedule Estimate Changes to LAAS:
Dollars in millions;
Baseline/Cost estimate year: January 1998 (baseline);
Estimated development costs: $530.1;
Initial operating capability: 2002;
Full operating capability: To be determined.
Baseline/Cost estimate year: September 1999;
Estimated development costs: $696.1;
Initial operating capability: 2001;
Full operating capability: To be determined.
Source: GAO presentation of FAA data.
[End of table]
FAA Faced Challenges in Approving LAAS:
FAA faced a number of challenges in approving LAAS for safe use in the
national airspace system, including (1) its inability to meet LAAS'
integrity requirement, (2) not always communicating with the contractor
about what was required to satisfy LAAS ground system requirements, and
(3) accelerating the LAAS schedule by setting milestones before
designing the system.
According to Honeywell officials, meeting the integrity requirement has
been perhaps the most difficult part of approving LAAS for safe use in
the national airspace system. Under FAA's integrity requirement for
LAAS, the system must alert the pilot with timely warnings when it
should not be used. However, FAA has not been able to develop a
solution to meet this requirement because it has not been able to prove
that the system is safe during solar storms. According to FAA
officials, one of the reasons that FAA has not been able to develop a
solution to meet this requirement is that a solar storm's effect on the
ionosphere has not been modeled. The modeling is scheduled for
completion in September 2004, and it will be used to design a monitor
for ionosphere anomalies that could be developed and deployed by fiscal
year 2009.
FAA also did not always communicate with the contractor about what was
required to satisfy LAAS ground system requirements. Initially, FAA was
in a partnership with industry, including Honeywell and others, to
develop a LAAS Category I precision approach and landing system, which
has a 200-foot ceiling height and one-half mile visibility. FAA
partnered with industry to develop LAAS because FAA would have to pay
industry only if industry achieved preset milestones, such as an
analysis of the LAAS system integrity requirement. However, the
partnership was not able to develop a system that FAA believed would
operate safely in the national airspace system. Consequently, FAA
decided to acquire LAAS on its own. In April 2003, FAA awarded a
contract to Honeywell to develop a LAAS Category I precision approach
and landing system. At the time the contract was awarded, FAA believed
that 80 percent of the LAAS was developed and met its ground system
requirements based on a review of documents. However, 5 months later,
after further review, FAA discovered that only about 20 percent of
development was complete. Nevertheless, Honeywell believes it met 80
percent of the LAAS requirements. Both parties attribute the
disagreement to lack of communication about what was needed to satisfy
the LAAS ground system requirements. In fiscal year 2005, FAA decided
to suspend funding and placed LAAS into its research and development
program due to a lack of software development and the inability of the
system to meet the integrity requirement. According to FAA officials,
the research needed to validate the integrity requirement of LAAS
Category I is scheduled to be completed by September 2005. If funds are
fully restored in fiscal year 2005, FAA believes that a LAAS Category I
system can be developed and deployed by fiscal year 2009.
FAA also experienced challenges in approving LAAS because it
accelerated the schedule in 1998 to meet system milestones before
completely designing the system and developing a solution for meeting
the LAAS integrity requirement. FAA originally planned to deploy LAAS
in 2002 but had to subsequently delay deployment to 2006 because of
additional development work, evolving requirements, and unresolved
issues regarding how the system would be approved. Lack of a solution
for verifying that its integrity requirement had been met and
incomplete software development were significant approval issues facing
the LAAS program.
Table 9 shows the major phases and time frames for approving the LAAS
ground system.
Table 9: LAAS Ground System Approval Timeline:
Phase: Concept of operations (initial);
Date: 1992.
Phase: Requirements setting: RTCA performance standards;
Date: September 1998.
Phase: Requirements setting: Creation of LAAS Integrity Panel;
Date: 1996.
Phase: Requirements setting: Establishment of LAAS government industry
partnership;
Date: 1999.
Phase: Requirements setting: Rebaseline #1;
Date: September 1999.
Phase: Requirements setting: Integrity requirement concerns
identified;
Date: December 2001.
Phase: Requirements setting: Requirements document final;
Date: June 2002.
Phase: Requirements setting: LAAS cost estimate change (Category I
only);
Date: April 2002.
Phase: Requirements setting: Contract award;
Date: April 2003.
Phase: Design and development: Software development issues identified;
Date: September 2003.
Phase: Design and development: Critical design review;
Date: Not complete.
Phase: Test and evaluation: Development test;
Date: Not complete.
Phase: Test and evaluation: Operational test and evaluation;
Date: Not complete.
Phase: Test and evaluation: Independent operational test and
evaluation;
Date: Not complete.
Phase: Operational readiness;
Date: Not complete.
Phase: Commissioning/Initial operating capability;
Date: Not complete.
Source: GAO presentation of FAA and RTCA data.
[End of table]
Certification of LAAS Aircraft Equipment Has Been Affected by Delays in
Ground System Approval:
LAAS aircraft equipment received design and production approval in
August 2004. It still awaits installation approval. (See table 10.)
Because LAAS' aircraft and ground components are linked, certification
of LAAS aircraft equipment has been affected by delays occurring during
ground system approval. For example, according to aviation industry
officials, requirement additions on LAAS' ground system led to
requirement additions on LAAS' aircraft equipment. According to
aviation industry officials, the addition of requirements to the ground
system increased the cost and time to develop aircraft equipment, which
changed the calculation for industry about whether developing LAAS
aircraft equipment was a worthwhile investment and discourages future
investment in aircraft equipment that will modernize the national
airspace system.
FAA's Aircraft Certification Office Needs to Coordinate Better with
Acquisitions Offices:
FAA's aircraft certification office completed the design and production
approval of LAAS aircraft equipment without coordinating with the
offices responsible for acquisition to determine the consequences of
certifying aircraft equipment before approval of the associated ground
system. According to an FAA official, once the aircraft certification
office has given design and production approval to the LAAS aircraft
equipment, it is not possible to make a change to the requirements for
the aircraft equipment so that they are better integrated with the
associated LAAS ground system. Consequently, LAAS ground system
developers may have to make more costly and time-consuming changes to
the ground system than would have been necessary if the aircraft
certification and acquisitions offices had coordinated their efforts.
Table 10: LAAS Aircraft Equipment Certification Timeline:
Phase: Concept of operations (initial);
Date: 1992.
Phase: Requirements setting: LAAS minimum operating performance
standards;
Date: 1995 to 2001.
Phase: Requirements setting: LAAS technical standard order development;
Date: March 2003.
Phase: Design and production approval;
Date: August 2004.
Phase: Installation approval;
Date: Not complete.
Phase: Operational approval;
Date: Not required[A].
Source: GAO presentation of FAA data.
[A] FAA first approved the use of GPS for aviation navigation in 1993,
so new aircraft equipment that uses GPS did not require a new
operational approval.
[End of table]
[End of section]
Appendix V: Standard Terminal Automation Replacement System Case
Illustration:
Background:
STARS is a joint Department of Transportation, FAA, and Department of
Defense (DOD) program established under 31 U.S.C. 1535, the Economy
Act, as amended, to replace aging FAA and DOD legacy terminal
automation systems with state-of-the-art terminal ATC systems. The
joint program is intended to avoid duplication of development and
logistic costs while providing easier transition of controllers between
the civil and military sectors. Civil and military air traffic
controllers across the nation are using STARS to direct aircraft near
major airports. FAA's goal for STARS is to provide an open, expandable
terminal automation platform that can accommodate future air traffic
growth and allow for the introduction of new hardware-and software-
based tools to promote safety, maximize operational efficiency, and
improve controllers' productivity. FAA believes that STARS will
facilitate efforts to optimally configure the terminal airspace around
the country, exchange digital information between pilots and
controllers, and introduce new position and surveillance capabilities
for pilots. (See fig. 5.)
Figure 5: Standard Terminal Automation Replacement System:
[See PDF for image]
[End of figure]
Status:
In June 2003, FAA first commissioned STARS for use at the Philadelphia
International Airport in Pennsylvania. Currently, STARS is fully
operational at 25 FAA terminal radar control facilities and 17 DOD
facilities. Under the Air Traffic Organization's new business model of
breaking large and complex programs into smaller phases to control cost
and schedule, STARS is a candidate for further deployment to about 120
FAA terminal radar control facilities. As shown in table 11, in April
2004, FAA changed STARS' cost and schedule estimates for the third time
and now estimates that it will cost $1.46 billion to deploy STARS at
the 50 most important terminal radar control facilities that provide
air traffic control services to 20 of the nation's top 35 airports. The
original baseline in February 1996 was $940 million for 172 systems.
The April 2004 estimate is an increase of about $500 million for 122
fewer systems (i.e., over 70 percent less) than originally planned.
Table 11: Cost and Schedule Estimate Changes to STARS:
Dollars in billions;
Baseline/Cost estimate year: February 1996[B];
Estimated development costs[A]: $0.94;
Projected date for first deployment of STARS: 1998;
Projected date for last deployment of STARS: 2005;
Number of FAA systems receiving STARS: 172.
Baseline/Cost estimate year: October 1999;
Estimated development costs[A]: $1.40;
Projected date for first deployment of STARS: 2002;
Projected date for last deployment of STARS: 2008;
Number of FAA systems receiving STARS: 188.
Baseline/Cost estimate year: March 2002;
Estimated development costs[A]: $1.33;
Projected date for first deployment of STARS: 2002;
Projected date for last deployment of STARS: 2005;
Number of FAA systems receiving STARS: 73.
Baseline/Cost estimate year: April 2004[C];
Estimated development costs[A]: $1.46;
Projected date for first deployment of STARS: 2003;
Projected date for last deployment of STARS: 2008;
Number of FAA systems receiving STARS: 50.
Source: GAO presentation of FAA data.
[A] This estimate includes development costs only and does not include
technology refresh and terminal automation enhancement.
[B] The February 1996 baseline included limited human factors
evaluations and a basic commercial off-the-shelf configuration.
[C] The April 2004 baseline occurred after STARS' commissioning in
June 2003 in Philadelphia, Pennsylvania.
[End of table]
FAA Faced Challenges in Approving STARS:
FAA faced challenges in approving STARS. Although controllers and
technicians were involved in developing requirements for STARS prior to
the 1996 contract award to Raytheon, the original approved acquisition
plan provided only limited human factors evaluation from controllers
and technicians during STARS' design and development phase. The
acquisition approach was to employ a commercial off-the-shelf system
with limited modifications, and the competition was limited to
companies with already operational ATC systems. In 1997, FAA
controllers, who were accustomed to using the older equipment, began to
voice concerns about computer-human interface issues that could hamper
their ability to monitor air traffic. For example, the controllers
noted that many features of the old equipment could be operated with
knobs, allowing controllers to focus on the screen. By contrast, the
STARS commercial system was menu-driven and required the controllers to
make several keystrokes and use a trackball, diverting their attention
from the screen. The maintenance technicians also identified
differences between STARS and its backup system that made monitoring
the system less efficient. For example, the visual warning alarms and
color codes identifying problems were not consistent between the two
systems. In 1997, FAA, the National Air Traffic Controllers
Association, the Professional Airways System Specialists, and Raytheon
formed a team to deal with these computer-human interface issues. The
team identified 98 air traffic and 52 airway facilities computer-human
interface enhancements to address these issues.
FAA and Raytheon restructured the contract to address the technicians'
and controllers' concerns. According to FAA, not involving controllers
and maintenance technicians caused FAA to revise its strategy for
approving STARS, which FAA estimates added $500 million and 3 years to
the schedule. The original STARS cost estimate of $940 million included
limited human factors evaluations and the use of a basic commercial
off-the-shelf configuration. This acquisition strategy was replaced by
an incremental development strategy that incorporated up front the
majority of human factors considerations and additional functionality
that were not included in the original cost estimate. This new
acquisition strategy added years to the development schedule and
significantly increased the system's requirements specifications.
These additional requirements resulted in both cost and schedule
growth. FAA's own guidance showed that limiting human factors
evaluations will result in higher costs and schedule delays. Initially,
it is more expensive (in terms of time and funding) to deal with human
factors considerations than to ignore them. However, an initial human
factors investment pays high dividends, in terms of costs and schedule,
in later stages of acquisition when changes are more costly and
difficult to make.
FAA also experienced challenges in approving STARS, partly, because of
aggressive scheduling. FAA's approach to approving STARS was oriented
to rapid deployment to meet critical needs. To meet these needs, FAA
compressed its original development and testing schedule from 32 months
to 25 months. This acceleration in schedule left only limited time for
human factors evaluations and not enough time for involvement of
controllers and maintenance technicians.
Table 12 shows the major phases and time frames associated with the
STARS approval process.
Table 12: STARS Ground System Approval Timeline:
Phase: Concept of operations (initial);
Date: 1993.
Phase: Requirements setting: Requirements setting occurred;
Date: 1994.
Phase: Requirements setting: Contract award;
Date: September 1996.
Phase: Design and development: System design review;
Date: December 1996.
Phase: Design and development: Human factors issues identified;
Date: 1997.
Phase: Design and development: STARS baseline change;
Date: October 1999.
Phase: Test and evaluation: Development test (Philadelphia, Full Stars-
2 Plus);
Date: January 2002.
Phase: Test and evaluation: Operational test and evaluation
(Philadelphia);
Date: August 2002.
Phase: Test and evaluation: Independent operational test and
evaluation (Philadelphia);
Date: January 2003.
Phase: Operational readiness/Commissioning (Philadelphia);
Date: June 2003.
Source: GAO representation of FAA data.
[End of table]
[End of section]
Appendix VI: Wide Area Augmentation System Case Illustration:
Background:
WAAS is a GPS-based navigation and landing system. According to FAA,
WAAS is to improve safety by providing precision guidance to aircraft
in all phases of flight at thousands of airports and landing strips,
including runways, where there is no ground-based landing capability.
To use WAAS for navigation, an aircraft must be equipped with a
certified WAAS receiver that is able to process the information carried
by GPS and WAAS geostationary satellite signals. Pilots are able to use
this information to determine their aircrafts' time and speed, and
latitude, longitude, and altitude positions. WAAS currently consists of
a network of 25 ground reference stations, 2 leased geostationary
satellites, 2 master stations, and 4 uplink (ground earth) stations.
The ground reference stations are strategically positioned across the
United States to collect GPS satellite data. (See fig. 6.) WAAS is
designed to improve the accuracy, integrity, and availability of
information coming from GPS satellites and to correct signal errors
caused by solar storms, among other things.
Figure 6: WAAS Architecture:
[See PDF for image]
[End of figure]
FAA expects that WAAS will improve the national airspace system by (1)
increasing runway capability; (2) reducing separation standards that
allow increased capacity in a given airspace without increased risk;
(3) providing more direct en route flight paths; (4) providing new
precision approach services; (5) reducing the amount of and simplifying
equipment on board aircraft; (6) saving the government money due to the
elimination of maintenance costs associated with older, more expensive
ground-based navigation aids; and (7) providing vertical guidance in
all phases of flight to improve safety.
Status:
In July 2003, FAA commissioned WAAS to provide initial operating
capability for 95 percent of the United States. In July 2003, the first
of the LPV[Footnote 29] approaches were provided whereby pilots could
safely descend to a 250-foot decision height.[Footnote 30] As of August
2004, there were about 20 LPV landing procedures published for WAAS.
With over 4,000 runways needing them, much work still needs to be done
to fully utilize the WAAS capability. FAA expects to have WAAS
available in the rest of the country, with the exceptions of a few
parts of Alaska, by the end of 2008 when it completes the addition of
13 ground reference stations and 2 leased geostationary satellites.
WAAS is not scheduled to achieve full (Category I) operating
capability, the final phase of WAAS when pilots will be able to use it
to navigate as low as 200 feet above the runway, until the 2013-2019
time frame.[Footnote 31]
As shown in table 13, FAA changed WAAS' cost and schedule estimates for
the third time in May 2004. According to FAA, the reasons for the May
2004 rebaselining were that the system was not able to achieve full
Category 1 capability and because of FAA internal and congressional
budget cuts. Under the May 2004 baseline, FAA estimates that WAAS
development costs will be about $2.0 billion, which is $1.5 billion
higher than the 1994 estimated development costs. Also, FAA has not yet
met some of its original performance goals, such as providing pilots
with the ability to navigate as low as 200 feet above the runway.
According to FAA, WAAS cannot easily achieve Category I as a single
frequency system because the error sources caused by solar storms are
difficult to correct without the use of a second civil aviation
frequency in space, which is the responsibility of the Department of
Defense. FAA, realizing the difficulty and risk associated with
developing a single frequency Category I system, decided to wait and
leverage the benefits of the White House policy to include the second
civil frequency on the GPS satellite network. According to FAA, budget
cuts and the decision to wait until the second civil frequency is
placed on the GPS constellation have caused it to extend the timeline
for reaching WAAS' full Category I operating capability to between 2013
and 2019.
Table 13: Cost and Schedule Baseline Changes to WAAS:
Dollars in millions.
Baseline year: 1994;
Estimated development costs: $509;
Initial operating capability: June 1997;
Full operating capability: December 2000.
Baseline year: January 1998;
Estimated development costs: $1,007;
Initial operating capability: August 1999;
Full operating capability: December 2001.
Baseline year: September 1999;
Estimated development costs: $1,683[A];
Initial operating capability: September 2000;
Full operating capability: December 2006.
Baseline year: May 2004;
Estimated development costs: $2,036[B];
Initial operating capability: July 2003;
Full operating capability: 2013-2019.
Source: GAO presentation of FAA data.
[A] The September 1999 estimate for WAAS development does not include
$1.3 billion in satellite service acquisition through 2020. In earlier
estimates, satellite service acquisition costs were included in the
cost of operating WAAS, not developing WAAS.
[B] The May 2004 estimate for WAAS development does not include $1.3
billion in satellite service acquisition through 2028. In earlier
estimates, satellite service acquisition costs were included in the
cost of operating WAAS, not developing WAAS.
[End of table]
FAA Faced Challenges in Approving WAAS:
FAA faced challenges in approving WAAS ground and satellite components
for use in the national airspace system, partly because of FAA's
accelerated scheduling, lack of effective coordination between its
aircraft certification office and acquisitions office, and technical
challenges which resulted in a delay meeting the integrity requirement.
FAA's challenges in approving WAAS began in 1994 when FAA accelerated
the implementation of milestones, including moving up the commissioning
of WAAS by 3 years. FAA originally planned to commission WAAS in 2000;
however, at the urging of government and aviation industry groups in
the 1990s, it decided to change WAAS' commissioning date to 1997. FAA
tried to develop, test, and deploy WAAS within 28 months, despite the
fact that software development alone was expected to take 24 to 28
months. FAA also set system milestones before completing the research
and development required to prove the system's capability. Although FAA
attempted to accelerate the implementation of WAAS, it wasn't until
July 2003, 6 years later, that it was able to commission WAAS with
initial operating capability.
Lack of full involvement between FAA's aircraft certification members
and the rest of the integrated product team contributed to delays in
approving WAAS. For example, although an integrated product team, which
included representatives from aircraft certification and acquisition
offices, was developing WAAS, it was not until September 1999, when the
aircraft certification office became fully involved, that FAA
recognized (1) the difficulty of meeting the integrity requirement--
that WAAS must alert the pilot in a timely manner when the system
should not be used--and (2) it did not have the technical expertise
needed. According to FAA officials, the reason coordination did not
occur was because the two offices had competing priorities, such as the
day-to-day aircraft equipment certification activities not associated
with the development of a new ATC system. This situation may have
developed because FAA's aircraft certification organization is more
accustomed to being involved after a project is developed, rather than
actively participating throughout project development.
The need to meet WAAS' integrity requirement also hampered FAA's
ability to approve WAAS for safe use in the national airspace system.
In December 1999, FAA found that WAAS did not meet the agency's
integrity requirement for precision approaches, and FAA recognized that
it did not have the technical expertise required to resolve the issue.
Therefore, in 2000, FAA established a team of satellite navigation
experts, which was referred to as the WAAS Integrity Performance Panel
and included representatives from the MITRE Corporation, Stanford
University, Ohio University, and the Jet Propulsion Laboratory.
Developing a solution to prove that the WAAS design met the integrity
requirement added about 2 years and 4 months to the approval process
and contributed to WAAS' cost growth. All of these challenges
contributed to a 6-year delay in WAAS' commissioning and a $1.5 billion
increase in its estimated total development costs through 2028,
exclusive of operating and maintaining geostationary satellites, which
were not part of WAAS' original 1994 baseline. Table 14 shows the major
phases and time frames associated with approving WAAS' ground system.
Table 14: WAAS Ground System Approval Timeline:
Phase: Concept of operations;
Date: June 1992.
Phase: Requirements setting: Operational requirements document;
Date: June 1994.
Phase: Requirements setting: Original contract award;
Date: August 1995.
Phase: Requirements setting: Current contract award;
Date: May 1996.
Phase: Design and development: Critical design review;
Date: December 1997.
Phase: Test and evaluation: Development test (failed);
Date: December 1999.
Phase: Test and evaluation: WAAS Integrity Performance Panel formed;
Date: January 2000.
Phase: Test and evaluation: Development test (passed);
Date: September 2002.
Phase: Test and evaluation: Operational test and evaluation;
Date: March 2003.
Phase: Operational readiness/Commissioning;
Date: July 2003.
Source: GAO presentation of FAA and RTCA data.
[End of table]
FAA Did Not Experience Major Challenges in Certifying the Aircraft
Equipment of WAAS:
In contrast to the challenges that it encountered during the approval
of the WAAS ground system, FAA did not encounter major challenges with
the certification of WAAS aircraft equipment, primarily because FAA had
an up-front approval agreement with one of the first applicants, United
Parcel Service Aviation Technology, through the creation and approval
of a safety plan and a project-specific certification plan. Table 15
shows the major phases and time frames associated with certifying the
aircraft equipment of WAAS. Currently, WAAS GPS receivers have been
certified and are available for use.
Table 15: WAAS Aircraft Equipment Certification Timeline:
Phase: Concept of operations;
Date: June 1992.
Phase: Requirements setting: RTCA WAAS minimum operational performance
standards (four major revisions);
Date: 1994 to November 2001.
Phase: Requirements setting: WAAS technical standard orders (four major
revisions);
Date: May 1998 to September 2002.
Phase: Design and production approval: Data submitted for supplemental
type certificate and technical standard order authorization;
Date: June 2, 2003.
Phase: Design and production approval: Technical standard order
authorization (United Parcel Service Aviation Technology);
Date: June 13, 2003.
Phase: Installation approval - Type certificate/Supplemental type
certificate (United Parcel Service Aviation Technology);
Date: June 27, 2003.
Phase: Operational approval;
Date: Not required[A].
Source: GAO presentation of FAA data.
[A] FAA first approved the use of GPS for aviation navigation in 1993;
therefore, new aircraft equipment that use GPS did not require a new
operational approval.
[End of table]
[End of section]
Appendix VII: GAO Contacts and Staff Acknowledgments:
GAO Contacts:
Katherine Siggerud, (202) 512-2834 or [Hyperlink, siggerudk@gao.gov];
Tammy Conquest, (202) 512-5234 or [Hyperlink, conquestt@gao.gov].
Staff Acknowledgments:
In addition to the individuals named above, other key contributors to
this report were Geraldine Beard, Gerald Dillingham, Seth Dykes, David
Hooper, Kevin Jackson, Gregg Justice III, Donna Leiss, and Kieran
McCarthy.
(540057):
FOOTNOTES
[1] Ground systems are air navigation facilities that, among other
things, aid in the guiding or controlling of flight, including the
landing and takeoff of aircraft. For the purposes of this report,
ground systems include the satellites that may be associated with them.
[2] Organized in 1935 and once called the Radio Technical Commission
for Aeronautics, RTCA is today known just by its acronym. RTCA is a
private, not-for-profit corporation that develops consensus-based
performance standards for air traffic control systems. RTCA serves as a
federal advisory committee and its recommendations are the basis for a
number of FAA's policy, program, and regulatory decisions. In 1999,
RTCA published its Final Report of the Task Force 4: Certification. In
2001, RTCA published RTCA Task Force 4 - Certification Implementation
Plans and Responsibilities.
[3] The Wide Area Augmentation System Integrity Performance Panel is a
team of satellite navigation specialists formed in January 2000 to help
FAA meet Wide Area Augmentation System's integrity requirement to alert
the pilot in a timely manner when it should not be used. FAA's
integrity requirement stipulates that the Wide Area Augmentation System
cannot fail to warn pilots of misleading information that could
potentially create hazardous situations more than once in 10 million
approaches.
[4] The Local Area Augmentation System Integrity Panel is a team of
satellite navigation specialists formed in 1996 but formally tasked in
2003 to help FAA meet the Local Area Augmentation System's requirement
to alert the pilot in a timely manner when it should not be used. FAA's
integrity requirement stipulates that the Local Area Augmentation
System cannot fail to warn pilots of misleading information that could
potentially create hazardous situations more than once in 10 million
approaches.
[5] FAA's Acquisition Management System was created in response to a
statutory mandate in 1995 that required FAA to implement a new
acquisition management system that is intended to provide for more
timely and cost-effective acquisitions.
[6] FAA's Air Traffic Services and Acquisitions Offices have recently
become part of FAA's newly created Air Traffic Organization.
[7] However, sometimes the need for a service or capability originates
in the private sector.
[8] The Joint Resources Council consists of senior FAA executives who
discuss and approve agency mission needs and investments in acquisition
programs.
[9] A type certificate is issued when an aircraft design is certified
to meet applicable airworthiness standards. A supplemental type
certificate is issued when an applicant has received FAA's approval to
modify an aircraft from its original design. A production certificate
applies to a company's manufacturing process and states that company
can produce products consistent with the approved design.
[10] However, sometimes the need for a service or capability originates
in the private sector.
[11] Requirements may include regulation-based requirements,
performance standards in technical standard orders, and/or
international requirements.
[12] If a technical standard order does not exist for aircraft
equipment, the applicant will be required to obtain design and
installation approval under the type certificate or supplemental type
certificate design approval process, which involves many of the same
activities involved in the technical standard order authorization
process. Upon completion of this phase, FAA issues a type certificate
or supplemental type certificate for one type of aircraft.
[13] GAO, Air Traffic Control: FAA's Modernization Efforts - Past,
Present, and Future, GAO-04-227T (Washington, D.C.: Oct. 30, 2003);
National Airspace System: Persistent Problems in FAA's New Navigation
System Highlight Need for Periodic Reevaluation, GAO/RCED/AIMD-00-130
(Washington, D.C.: June 12, 2000); and National Airspace System: Status
of FAA's Standard Terminal Automation Replacement System, GAO-02-1071
(Washington, D.C.: Sept. 17, 2002).
[14] Human factors evaluation examines how humans interact with
machines and identifies ways to enhance operators' performance and
minimize errors.
[15] GPS is a space-based, radio-navigation system consisting of a
constellation of satellites and a network of ground stations used for
monitoring and control. A minimum of 24 GPS satellites orbit the Earth
at an altitude of approximately 11,000 miles, providing users with
accurate information on position, velocity, and time of a GPS-equipped
object, such as an aircraft, anywhere in the world and in all weather
conditions.
[16] In addition, some development costs, such as required design
changes discovered during early development, were not included in the
1994 baseline. When these development costs were captured in the 1999
baseline and then again in the 2004 baseline, there was a net increase
in development costs of $1.5 billion through 2028. However, these costs
do not include operating and maintaining geo satellites, which were not
part of WAAS' original 1994 baseline and added an additional $1.3
billion in development costs.
[17] Department of Transportation's Inspector General, FAA Needs to
Reset Expectations for LAAS Because Considerable Work Is Required
before It Can Be Deployed for Operational Use, AV-2003-006 (Dec. 16,
2002).
[18] Build 1A was the second CPDLC development stage, yet to be
completed, that was designed to increase the CPDLC message set and
include assignment of speeds, headings, and altitudes as well as a
route clearance function.
[19] GAO, National Airspace System: Problems Plaguing the Wide Area
Augmentation System and FAA's Actions to Address Them, GAO/T-RCED-00-
229 (Washington, D.C.: June 29, 2000).
[20] RTCA, Final Report of the Task Force 4: Certification (1999) and
RTCA Task Force 4 - Certification Implementation Plans and
Responsibilities (2001).
[21] GAO-04-227T and National Airspace System: FAA Has Implemented Some
Free Flight Initiatives, but Challenges Remain, GAO/RCED-98-246
(Washington, D.C.: Sept. 28, 1998).
[22] Organizational designees perform functions for FAA to minimize
FAA's administrative burden.
[23] Organized in 1935 and once called the Radio Technical Commission
for Aeronautics, RTCA is today known just by its acronym. RTCA is a
private, not-for-profit corporation that develops consensus-based
performance standards for ATC systems. RTCA serves as a federal
advisory committee and its recommendations are the basis for a number
of FAA's policy, program, and regulatory decisions. In 1999, RTCA
published its Final Report of the Task Force 4: Certification. In 2001,
RTCA published RTCA Task Force 4 - Certification Implementation Plans
and Responsibilities.
[24] Multilateration is achieved through the strategic placement of
sensors around the airport grounds to report the location of aircraft
and vehicles.
[25] A runway incursion is any occurrence in the airport runway
involving an aircraft, vehicle, person, or object on the ground that
creates a collision hazard or results in a loss of required separation
between two aircraft during takeoff or landing.
[26] An altimeter is an instrument for measuring altitude.
[27] GPS is a space-based, radio-navigation system consisting of a
constellation of satellites and a network of ground stations used for
monitoring and control. A minimum of 24 GPS satellites orbit the Earth
at an altitude of approximately 11,000 miles, providing users with
accurate information on position, velocity, and time of a GPS-equipped
object, such as an aircraft, anywhere in the world and in all weather
conditions.
[28] Category I precision approach has a 200-foot ceiling/decision
height and visibility of one-half mile. Category II precision approach
has a 100-foot ceiling/decision height and visibility of one-quarter
mile. Category III precision approach and landing has a decision height
less than 100 feet down to the airport surface.
[29] LPV is an acronym with no specific definition today but once stood
for Lateral Precision Vertical.
[30] A ceiling or decision height is the height above the Earth's
surface to the lowest layer of clouds or obscuring phenomena.
[31] Category I precision approach has a 200-foot ceiling/decision
height and visibility of one-half mile.
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