Audit Reports

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ADS-B Benefits Are Limited Due to a Lack of Advanced Capabilities and Delays in User Equipage

Requested by the Chairman and Ranking Member of the House Committee on Appropriations, Subcommittee on Transportation, Housing and Urban Development, and Related Agencies, and in accordance with the FAA Modernization and Reform Act of 2012
Project ID: 

The Automatic Dependent Surveillance-Broadcast (ADS-B) system is central to the Federal Aviation Administration’s (FAA) Next Generation Air Transportation System (NextGen) goals. ADS-B technology is expected to allow FAA to transition from ground-based radar to a satellite-based system for managing air traffic. However, in 2010, we reported that FAA faces significant risks and challenges in finalizing ADS-B’s technical requirements, managing its cost and schedules, and encouraging airspace users to equip with ADS-B avionics.

FAA recently completed ADS-B’s ground infrastructure with the deployment of 624 ground radio stations in April 2014. However, controller and pilot use of ADS-B throughout the National Airspace System (NAS) remains years away, in part because FAA has yet to resolve significant hazards identified during operational testing or conduct more rigorous testing of the entire system. Moreover, while ADS-B will provide some useful services—particularly in areas with no radar coverage—the system’s initial capabilities and benefits are limited. According to FAA, airspace users will gain the most benefits with the advanced capabilities of ADS-B In, which is expected to provide pilots enhanced merging and spacing capabilities for airport arrivals. However, requirements for ADS-B In advanced capabilities continue to evolve, creating significant challenges for certifying and equipping users with ADS-B avionics. Finally, the total cost and timeline to implement ADS-B and provide benefits for FAA and airspace users remain uncertain. FAA has increased its cost estimates for the total program by approximately $400 million and continues to adjust expected ADS-B benefits. As a result, FAA’s costs for the current ADS-B program now outweigh the potential benefits to users, and risks of further cost and schedule increases remain.

We made six recommendations to ensure ADS-B is operationally suitable, safe to deploy in the NAS, and a viable program. FAA stated that it generally concurs with all but one of the recommendations. All recommendations will remain open and unresolved until FAA provides specific information on its planned actions and completion dates, as requested in our draft report.




Closed on 09.03.2019
No. 1 to FAA

Resolve performance problems identified during FAA's independent operational testing on ADS-B. Also, conduct end-to-end testing of the ADS-B system to determine how it can be used by controllers and pilots to safely manage and separate traffic in the NAS during all phases of flight.

Closed on 03.15.2017
No. 2 to FAA

Develop a schedule and plan to expedite the continued development and deployment of SBS Monitor and ensure that the system is adequately staffed and funded so it can effectively access the performance and integrity of the ADS-B system now and as it evolves.

Closed on 10.28.2016
No. 3 to FAA

Develop and implement a plan to improve communications with the aviation community to ensure it understands the intended use of ADS-B services and applications being provided, including that ADS-B initial capabilities are for advisory use only.

Closed on 09.03.2019
No. 4 to FAA

Determine when FAA will be in a position to introduce and support ADS-B In capabilities for congested airports, and identify the changes that may be required for ADS-B ground and air components for using advanced ADS-B In capabilities.

Closed on 05.04.2017
No. 5 to FAA

Develop a clearly defined and expedited schedule for determining the end-state for the ADS-B program with cost and schedule baselines, and provide written notification to Congress and other decision makers so that they have more complete information on the total program cost, schedule, and expected services.

Closed on 03.02.2016
No. 6 to FAA

Determine whether cost savings could be realized by delaying payment of subscription fees for ADS-B services at locations where (a) users are not equipped with rule-compliant avionics to provide and receive ADS-B services at those locations, and (b) air traffic control automation systems have not been modernized to support ADS-B services.