Air Traffic Control: FAA's Analysis of Costs and Benefits Drove Its Plans to Improve Surveillance in U.S. Oceanic Airspace

Recent developments in surveillance technologies, which provide an aircraft's location to air traffic controllers, have the potential to improve air traffic operations over the oceans. FAA has explored how to improve surveillance capabilities in U.S. oceanic airspace to take advantage of new international separation standards that could lead to the more efficient use of this airspace.

GAO was asked to review planned improvements to aircraft surveillance. This report examines: (1) FAA's approach to enhancing surveillance capabilities to improve safety and efficiency in U.S. oceanic airspace and (2) selected aviation stakeholders' perspectives on FAA's approach.

GAO reviewed documents related to FAA's planned investment in enhanced oceanic surveillance and interviewed FAA officials working on this effort. Interviews included those with the Air Traffic Organization and air traffic controllers who manage U.S. oceanic airspace. GAO surveyed representatives of 14 commercial airlines, including 11 U.S. and foreign passenger airlines, which were selected based on factors such as flight volume; and 3 U.S. cargo airlines, which were selected based on tons of cargo shipped. GAO also interviewed other aviation stakeholders, including trade associations, unions representing pilots, and foreign air navigation service providers that manage airspace adjacent to U.S. oceanic airspace.

The Federal Aviation Administration (FAA) evaluated two aircraft surveillance technologies that would allow aircraft to safely fly in closer proximity while in oceanic airspace. Based on its evaluation, FAA committed to using one in the near term and to continue to study another for future use. Specifically, in April 2019, FAA committed to implement by 2022 new international standards that allow reduced distances between aircraft, called minimum separation standards. These reduced distances would be enabled by a surveillance technology known as enhanced Automatic Dependent Surveillance-Contract (ADS-C). FAA also decided to continue studying the use of another enhanced surveillance technology known as space-based Automatic Dependent Surveillance-Broadcast (ADS-B)—to further improve surveillance in U.S. airspace. Both technologies offer increased frequency in reporting of an aircraft's location, which enhances safety, and can support new minimum separation standards. FAA decided to proceed with enhanced ADS-C in the near term because the efficiency benefits to airspace users exceeded the costs of more frequent location reporting and air traffic control system upgrades by 2 to 1. In contrast, FAA determined that the costs of using space-based ADS-B in U.S. oceanic airspace outweigh the efficiency benefits by 6 to 1. FAA officials added that operational challenges to using space-based ADS-B to manage air traffic in U.S. oceanic airspace have not yet been resolved. FAA plans to continue studying potential uses for space-based ADS-B in U.S. airspace to determine if benefits can outweigh the costs (see figure).

GAO found that most selected airlines (11 of 14) support FAA's overall approach to enhance oceanic surveillance. Selected airlines also said they expect the new minimum separation standards to improve access to more direct and fuel-efficient routes. FAA is taking steps to provide these benefits by restructuring routes in one area of U.S. oceanic airspace and by applying new minimum standards to give aircraft better access to fuel-efficient altitudes. According to FAA officials, however, additional benefits, such as redesigning other U.S. oceanic airspace, expected by selected airlines are limited by (1) relatively low rates of aircraft equipage with the technology that enables reduced separation and (2) the frequency of disruptive weather patterns in parts of U.S. oceanic airspace.

Over the past decade, the Federal Aviation Administration (FAA) has  provided air traffic control services to over 18 million flights traversing the  airspace above the Atlantic, Pacific, and Arctic oceans. With international  air traffic expected to grow, FAA must modernize to continue meeting its  goal of providing the safest, most efficient airspace system in the world.  Recent developments in surveillance technologies, which provide an  aircraft’s location and other information to air traffic controllers, have the  potential to help FAA manage oceanic air traffic more efficiently while  maintaining a high level of safety. For example, Aireon—in partnership  with air navigation service providers from around the world and Iridium  Communications—is using a constellation of recently deployed satellites  to provide near real-time surveillance of suitably equipped aircraft  anywhere in the world.

You asked us to review planned improvements to aircraft surveillance in  oceanic airspace. This report addresses:

FAA’s approach to enhancing surveillance capabilities to improve  safety and efficiency in U.S. oceanic airspace and  selected aviation stakeholders’ perspectives on FAA’s approach to  enhancing surveillance.

To address both of our objectives, we reviewed FAA’s and other aviation  stakeholders’ documents on the management and organization of U.S.  oceanic airspace; the functionality and use of communication, navigation,  and surveillance equipment in aircraft flying in U.S. oceanic airspace; and  descriptions of the enhanced surveillance technologies that were being  considered by FAA—space-based Automatic Dependent Surveillance- Broadcast (ADS-B) and enhanced Automatic Dependent Surveillance- Contract (ADS-C). To understand how space-based ADS-B and  enhanced ADS-C would function, we interviewed representatives from  Aireon, which offers the space-based ADS-B service, and Inmarsat,  which provides the primary satellite communication network used by the  providers of ADS-C services. We also interviewed other aviation industry  stakeholders, including trade associations representing aircraft operators  and unions representing pilots.

To examine FAA’s approach to enhancing surveillance capabilities in U.S.  oceanic airspace, we reviewed FAA documents and interviewed FAA  officials. Specifically, we reviewed documents prepared by the Advanced  Surveillance Enhanced Procedural Separation (ASEPS) program for  FAA’s planned investment decision. These documents included the  business case analysis and safety risk management assessments of  enhanced surveillance technologies. In reviewing the business case  analysis, we did not independently evaluate the methodology or data  sources used. We interviewed FAA officials and program managers who  are working on different elements of FAA’s efforts to enhance surveillance  in U.S. oceanic airspace, including relevant offices within the Air Traffic  Organization; other offices within FAA, such as the Flight Standards  Service; and the contractors who prepared FAA’s business case  analyses. We interviewed FAA air traffic controllers and their union  representatives at the Anchorage, New York, and Oakland air route traffic  control centers, which are responsible for managing air traffic flying  through U.S. oceanic airspace. We also interviewed or received written  responses from representatives of the air navigation service providers in  Canada, Japan, Portugal, and the United Kingdom—which are  responsible for oceanic airspace adjacent or close to U.S. oceanic  airspace—to understand their plans to enhance surveillance capabilities.

To obtain selected aviation stakeholders’ perspectives on FAA’s  approach to enhancing surveillance in U.S. oceanic airspace, we selected  14 U.S. and foreign commercial airlines, including passenger and cargo  airlines. Using FAA data from fiscal year 2016, we selected 10 passenger  airlines with the highest flight volumes in U.S. oceanic flight information  regions. We selected an additional passenger airline because it planned  to begin service in U.S. oceanic airspace. We also selected three large  U.S. cargo airlines, based on tons of cargo transported, to ensure that the  cargo airlines’ perspective was represented. We conducted a follow-up  survey of these 14 airlines to obtain their responses on safety in oceanic  airspace, benefits of reduced aircraft separation standards, and FAA’s  planned approach to enhancing surveillance capabilities. In this report,  we use the following conventions in reference to information obtained  from the 14 selected airlines: “several” is three to seven, “many” is eight  to 10, and “most” is 11 to 13. Further details about our scope and  methodology are in appendix I.

We conducted this performance audit from March 2018 to July 2019 in  accordance with generally accepted government auditing standards.  Those standards require that we plan and perform the audit to obtain  sufficient, appropriate evidence to provide a reasonable basis for our  findings and conclusions based on our audit objectives. We believe that  the evidence obtained provides a reasonable basis for our findings and  conclusions based on our audit objectives.

FAA, within the U.S. Department of Transportation, provides air traffic  services for the continental United States (domestic airspace) and over  parts of the Atlantic, Pacific, and Arctic oceans (oceanic airspace). More  than 24 million square miles of oceanic airspace are under U.S. control.  This airspace is divided into flight information regions (flight regions):  Anchorage Arctic, Anchorage Oceanic, New York Oceanic, and Oakland  Oceanic.

Air traffic service (ATS) route is a specified  route designed to channel the flow of traffic as  necessary for the provision of air traffic  services. ATS routes are defined by  predetermined geographical positions— waypoints. For example, ATS route G344 is  published by FAA and is defined by  waypoints.

Organized Track System is a series of ATS  routes. For example, A590, R591, and G344,  along with other ATS routes, comprise the  North Pacific Route System.

In areas with high flight volume, such as between California and Hawaii,  FAA publishes air traffic service (ATS) routes that allow air traffic  controllers to handle large volumes of traffic. A set of ATS routes—an  organized track system—functions as a freeway in the sky, with routes  serving as lanes (see sidebar). ATS routes may be “fixed” or “flexible.” A  fixed route does not change; whereas a flexible route changes daily  depending on weather patterns, such as prevailing winds. As detailed in  industry reports, multiple factors—including weather conditions,  congestion, and airspace restrictions—affect whether aircraft operators  plan to fly on ATS routes published by FAA or on routes they determine to  be the most efficient for that flight (i.e., user-preferred routes). Figure 1  shows U.S. oceanic airspace and the location of various organized track  systems.

To fly through U.S. oceanic airspace, aircraft operators (e.g., airlines) file  a flight plan, which includes the departure and arrival airports and the  planned route (i.e., the path the aircraft plans to take to get to its  destination). Air traffic control may clear the flight plan as filed—with no  changes—and/or makes changes to an aircraft’s planned route during the  flight.

To manage air traffic, air traffic controllers must be able to monitor an  aircraft’s position as it flies along its planned route. As we have previously  reported, in domestic airspace, radar and ground-based Automatic  Dependent Surveillance-Broadcast (ADS-B) technology provides this  surveillance information. Radar is a ground-based system that provides  information on an aircraft’s position to air traffic control facilities. Ground- based ADS-B uses equipment installed in aircraft (transmitters) to  broadcast an aircraft’s position, altitude, and other information to ground  stations, which transmit the data to air traffic control facilities.  Surveillance information from radar and ADS-B is nearly instantaneous— allowing domestic air traffic controllers to effectively “see” where an  aircraft is at all times. FAA manages radar and ground-based ADS-B  infrastructure, in some cases through contracts. Through its contract with  the provider of ADS-B services, FAA also pays for the cost of transmitting  ADS-B messages from aircraft to air traffic control in domestic airspace.

Future Air Navigation System (FANS)  Equipage in U.S. Oceanic Airspace  By 2020, FAA estimates that about 80 percent  of aircraft flying in U.S. airspace above the  Atlantic Ocean will be equipped with FANS as  will 84 percent of aircraft flying in U.S.  airspace above the Pacific Ocean. However,  FANS equipage varies within these airspaces.  In the New York flight region, specifically  along the West Atlantic Route System, FAA  estimates that by 2020 the FANS equipage  rate will be 66 percent—lower than other  sectors of Atlantic airspace. Similarly, in the  Oakland flight region, along the Central East  Pacific Route System, FAA estimates that by  2020 the FANS equipage rate will be 75  percent—lower than found in other sectors of  Pacific airspace. controllers receive reports on an aircraft’s position from a radio operator  who receives verbal updates from pilots using a high frequency radio or  automatically through a technology called Future Air Navigation System  (FANS):

High frequency radio allows pilots to speak with a third-party radio  operator and share surveillance information via spoken position  reports at mandatory reporting points. The radio operator then relays  position reports as a data message to air traffic controllers.

FANS includes a communication system—Controller Pilot Data Link  Communications (CPDLC)—and a surveillance system—Automatic  Dependent Surveillance-Contract (ADS-C). CPDLC allows pilots and  air traffic controllers to communicate directly by exchanging text- based messages. Through ADS-C, air traffic control can request  position reports and specify their frequency as well as the information  they should include. As we have previously reported, position reports  sent through ADS-C can transmit at defined time intervals, when  specific events occur such as pilot deviation from the planned route,  or at the request of air traffic control. ADS-C reports sent at a  defined time interval are called periodic reports—in U.S. oceanic  airspace these are typically sent every 10 to 14 minutes.

As detailed in an industry report, aircraft operators pay to use the satellite  communication networks required to transmit communication and  surveillance information to air traffic control in oceanic airspace. In  addition, aircraft operators are responsible for the cost of equipping their  aircraft with communication, navigation, and surveillance equipment.

To help them manage oceanic airspace, U.S. air traffic controllers use a  computer system called Advanced Technologies and Oceanic  Procedures (ATOP). ATOP is a flight data processing system that  controllers use at their workstations. It provides oceanic air traffic  controllers with several automated tools to assist in maintaining aircraft at  safe distances from one another, coordinate with air traffic controllers in  other flight regions, and facilitate controller-pilot communication through  CPDLC, among other things. ATOP incorporates information from aircraft  flight plans and position reports allowing controllers to monitor an  aircraft’s progress, ensure it is following the route cleared by air traffic  control, and to continually check for any potential conflicts between  aircraft flying through their area of control, i.e., aircraft that could get too  close to one another.

Separation standards—the minimum distances required between  aircraft—help ensure that aircraft do not collide with one another. As  illustrated in figure 2, separation standards dictate the minimum required  longitudinal, lateral, and vertical distance between aircraft.

The International Civil Aviation Organization (ICAO) publishes minimum  separation standards for oceanic airspace. Using ICAO separation  standards as the minimum, FAA sets the separation standards and  aircraft requirements that are used in U.S. oceanic airspace. Currently,  the minimum distance that must be maintained between aircraft in U.S.  oceanic airspace is 30 nautical miles lateral and 30 nautical miles  longitudinal. To be eligible for this U.S. oceanic minimum separation  standard, an aircraft must be equipped with FANS, in addition to meeting  other communication, navigation, and surveillance requirements. For  aircraft without FANS, the minimum distance required between aircraft is  larger, at least 50 nautical miles lateral and approximately 80 nautical  miles longitudinal.

While requiring more distance between aircraft helps ensure safety, it  means less airspace capacity and may result in fewer direct and fuel- efficient routes. To maintain the required separation distance between  aircraft, air traffic control may instruct an aircraft—either before or during  flight—to fly at an altitude or along a route that is not the most efficient for  that aircraft in terms of flight time or fuel usage. For example, aircraft  spaced 50 nautical miles apart laterally and longitudinally are less likely to  be able to fly at a fuel-efficient altitude (e.g., 38,000 feet) as fewer aircraft  will fly at that altitude, especially in congested airspace. In contrast, when  aircraft are spaced 30 nautical miles apart laterally and longitudinally,  more aircraft can fly at fuel-efficient altitudes.

FAA may adopt ICAO’s minimum separation standards for the oceanic  airspace it manages or it can adopt standards that require aircraft to fly  farther apart than ICAO’s minimum standards. For example, ICAO  published the minimum separation standard for 30 nautical miles  longitudinal in 2002. FAA began applying these minimum separation  standards in the Oakland Oceanic flight region in 2007, in the Anchorage  Oceanic flight region in 2012, and in the New York Oceanic flight region in  2013.

In 2016, ICAO published a new minimum separation standard, which  allows a minimum lateral distance of 23 nautical miles. FAA has not yet  adopted the 23 nautical mile lateral standard. Since 2012, ICAO has  worked to develop new minimum separation standards for oceanic  airspace that require even less distance between properly equipped  aircraft. These new minimum separation standards are based on  improved surveillance capabilities, with aircraft using space-based ADS-B  potentially eligible to use one set of reduced minimum separation  standards (19 nautical miles lateral and 17 nautical miles longitudinal)  and aircraft using enhanced ADS-C potentially eligible to use a different  set of minimum separation standards (23 nautical miles lateral and 20  nautical miles longitudinal). These new minimum separation standards  are undergoing review with final approval expected in 2020.

FAA’s Advanced Surveillance Enhanced Procedural Separation (ASEPS)  program, which is part of FAA’s Air Traffic Organization, was tasked with  examining how to increase the efficiency and capacity of operations in  U.S. oceanic airspace using enhanced surveillance technologies. In  fiscal years 2015 through 2018, congressional committees directed FAA  to accelerate its evaluation of space-based ADS-B and provided funding  for that purpose. In response, the ASEPS program, among other things,  evaluated and compared the costs and benefits of two technologies that  could improve surveillance capabilities in U.S. oceanic airspace— enhanced ADS-C and space-based ADS-B. Following are descriptions  of how these enhanced surveillance technologies work:

Enhanced ADS-C. Uses the same ADS-C technology already  installed on FANS-equipped aircraft, but ATOP would request that  automatic position reports be sent more frequently to air traffic  control. Aircraft equipped with ADS-C and transmitting position  reports every 3.2 minutes would be eligible for ICAO’s proposed  minimum separation standard of 20 nautical miles longitudinal. ICAO’s  23 nautical miles lateral separation standard, published in 2016, does  not require more frequent ADS-C position reports.

Space-based ADS-B. Uses low-earth orbiting satellites to capture  automatic reports broadcast by ADS-B transmitters installed on  aircraft, which will be required for aircraft flying at certain altitudes in  domestic U.S. airspace by 2020. ADS-B messages are to be  received by air traffic control about every 8 seconds. Aircraft equipped  with ADS-B transmitters using the space-based ADS-B system and  also equipped with required communication and navigation  technologies, would meet the eligibility requirements for ICAO’s  proposed minimum separation standards of 19 nautical miles lateral  and 17 nautical miles longitudinal.

As shown in figure 3, enhanced ADS-C and space-based ADS-B use  similar transmission networks but relay different information at different  time intervals to air traffic control.

To compare these options, FAA prepared a business case analysis that  estimated the costs to the agency and aircraft operators, identified safety  benefits from enhanced surveillance, and identified and calculated the  value of operational efficiency benefits from using reduced minimum  separation standards enabled by enhanced ADS-C and space-based  ADS-B. For more detail on the costs and benefits included in FAA’s  business case analysis, see appendix IV. FAA used this business case  analysis to inform its decision on which enhanced surveillance technology  to use to support new minimum separation standards.

FAA Is Implementing New Oceanic Separation Standards in the Near Term and Will Study Options to Enhance Surveillance

FAA is implementing new minimum separation standards supported by  enhanced ADS-C in U.S. oceanic airspace. FAA does not plan to use  space-based ADS-B in U.S. oceanic airspace; instead, the agency  intends to study how to use space-based ADS-B in other U.S. airspace  over the next 5 years. According to FAA, this approach is driven by its  analysis of the costs and benefits of each enhanced surveillance  technology and the safety and operational challenges of using space- based ADS-B in U.S. oceanic airspace.

FAA Intends to Implement New Minimum Separation Standards Using Enhanced ADS-C in U.S. Oceanic Airspace By 2022

According to FAA officials and based on project status reports, FAA is  implementing new minimum separation standards in U.S. oceanic  airspace that are supported by enhanced ADS-C. The agency plans to  apply these standards in all sectors of U.S. oceanic airspace by 2022, as  shown in figure 4. Specifically, FAA will begin operational use of the 23  nautical mile lateral separation standard in U.S. oceanic airspace in 2021  and the 20 nautical mile longitudinal separation standard in 2022.

In April 2019, FAA executives approved a schedule and funding for the  implementation of these new minimum separation standards (i.e., 23  nautical miles lateral and 20 nautical miles longitudinal) in U.S. oceanic  airspace using enhanced ADS-C. To implement these new standards,  FAA officials are upgrading ATOP and working through a review process  required to change minimum separation standards in U.S. oceanic  airspace. This review process involves 18 milestones, including safety  assessments, coordinating with industry and international participants,  and developing procedures and training materials for pilots and air traffic  controllers.

According to FAA officials, the costs and benefits of pursuing this  approach—using enhanced ADS-C to support the adoption of new  minimum separation standards, i.e., 23 nautical miles lateral and 20  nautical miles longitudinal—drove this decision. Specifically, FAA found  that the benefits to airspace users of using enhanced ADS-C to enable  new minimum separation standards, such as improved access to fuel- efficient altitudes, outweighed, by 2 to 1, the total costs, including FAA’s  costs to upgrade ATOP and the aircraft operators’ data costs due to more  ADS-C position reports.

In addition, FAA officials said that although new minimum separation  standards can provide benefits to airspace users overall, the current  minimum separation standards support safe operations for current and  anticipated levels of air traffic in U.S. oceanic airspace. Officials noted  that the benefits to airspace users of new minimum standards are  contingent on the communication, navigation, and surveillance  capabilities of aircraft in an airspace and the frequency of disruptive  weather patterns. According to FAA officials and air traffic controllers we  spoke with, the current minimum separation standards (i.e., 30 nautical  miles lateral and longitudinal) are rarely used as the density of aircraft  traffic in U.S. oceanic airspace does not require such close spacing. In  areas of U.S. oceanic airspace with higher traffic volumes, such as along  the West Atlantic Route System and the Central East Pacific Route  System, the number of aircraft without FANS and the frequency of  disruptive weather patterns often prevent air traffic controllers from  applying current minimum separation standards. Officials noted that they  are also implementing the new minimum separation standards to  harmonize with adjacent air navigation service providers.

FAA’s ability to implement these new minimum separation standards (i.e.,  23 nautical miles lateral and 20 nautical miles longitudinal) in their  documented time frames depends on the success of planned ATOP  upgrades. For example, FAA officials and air traffic controllers we spoke  to told us that there is a current limitation in ATOP that under certain  circumstances, air traffic controllers cannot rely on the system to ensure  that minimum longitudinal separation distances are maintained. As a  result, air traffic controllers cannot grant aircraft flying at the current  minimum longitudinal separation distance their requests to deviate from  their planned route for reasons such as avoiding disruptive weather or  turbulence. Representatives of the union that represents FAA air traffic  controllers told us this limitation must be resolved before new separation  standards (i.e., 23 nautical miles lateral and 20 nautical miles longitudinal)  can be safely applied. FAA officials told us that they have developed an  ATOP software upgrade that could resolve this issue; the upgrade is  scheduled to occur in 2021. However, if this upgrade does not resolve the  issue or it takes longer to resolve than planned, implementation of the  new minimum separation standards could be delayed.

Due to Cost, Safety, and Operational Concerns, FAA Plans to Study Space-Based ADS-B in Other U.S. Airspace

According to FAA officials, the cost of space-based ADS-B was a major  factor in their decision not to use this technology in U.S. oceanic airspace.  FAA’s initial business case analysis found that the costs of using space- based ADS-B to enable reduced separation outweighed the benefits.  Specifically, the estimated subscription costs to access the data collected  by space-based ADS-B and needed upgrades to ATOP outweighed the  estimated benefits to airspace users by 6 to 1. As mentioned above,  according to FAA officials, current minimum separation standards allow  safe operations for current and anticipated levels of air traffic in U.S.  oceanic airspace. Therefore, without a positive business case (i.e.,  benefits are larger than the costs), FAA officials decided they could not  pursue this enhanced surveillance option for U.S. oceanic airspace.

FAA officials we interviewed also had safety concerns about using space- based ADS-B to manage reduced separation in U.S. oceanic airspace at  this time. Specifically, FAA officials told us the operational considerations  for most of the U.S. oceanic airspace were not reflected in the data used  by ICAO to model the safety of these standards—air traffic control  response times and rates of approved and unapproved aircraft weather  deviations. For example, the ICAO panel responsible for analyzing the  safety of the proposed minimum separation standards enabled by space- based ADS-B used data from the North Atlantic on the number of times  aircraft deviate without authorization from their expected flight plan due to  weather conditions. According to FAA officials, other oceanic regions— especially in U.S. oceanic airspace—experience a higher frequency of  these deviations. As a result, FAA officials do not plan to use the new  minimum separation standards enabled by space-based ADS-B (i.e., 19  nautical miles lateral and 17 nautical miles longitudinal) until FAA can  further address how to implement these standards in U.S. oceanic  airspace.

FAA officials we interviewed also had operational concerns about using  space-based ADS-B with ATOP to manage separation between aircraft in  U.S. oceanic airspace. Specifically, FAA officials told us that ATOP is  designed to use information in ADS-C position reports—i.e., an aircraft’s  current location, the next waypoint the aircraft will pass and at what time,  and the subsequent waypoint the aircraft will pass—to determine potential  conflicts in aircraft flight paths. Without this information, ATOP would not  receive the data it uses to detect conflicts within the next 2 hours of a  flight, according to FAA officials. ADS-B messages do not include this  information and therefore, space-based ADS-B would not replace ADS-C  in U.S. oceanic airspace.

Due to these cost, safety, and operational concerns with using space- based ADS-B to enable reduced separation, the ASEPS program  deferred a decision, originally scheduled for September 2018, on whether  to invest in using space-based ADS-B in U.S. oceanic airspace. FAA  officials said that while they have not yet found a positive business case  for using space-based ADS-B in U.S. oceanic airspace, they will further  study space-based ADS-B in U.S. offshore and oceanic airspace.  According to FAA officials, they expect further study to identify additional  benefits and resolve operational challenges to using space-based ADS-B.

FAA’s Plans to Study Space- Based ADS-B in U.S. Offshore and Oceanic Airspace

FAA officials and documents indicate that the agency has near-term,  medium-term, and long-term plans with goals, milestones, and time  frames to evaluate how to use space-based ADS-B in U.S. airspace over  the next 5 or more years. These plans include an operational evaluation  and other studies to assess the uses and benefits of space-based ADS-B  in U.S. airspace. FAA officials told us they expect to use findings from the  near-term operational evaluation to inform medium-term and long-term  plans.

According to FAA officials and documentation, the ASEPS program  intends to conduct an operational evaluation of space-based ADS-B in  U.S. offshore airspace managed by controllers based in Miami, as shown  in figure 5.

FAA officials told us that this operational evaluation will assess space- based ADS-B with the computer system used by domestic air traffic  controllers—the En Route Automation Modernization (ERAM) system.  The operational evaluation will also focus on how to use space-based  ADS-B in the heavily travelled airspace between the U.S. East Coast and  islands in the Caribbean and assess potential benefits. As detailed by  FAA officials, a radar that is located on Grand Turk Island provides  critical data to U.S. air traffic controllers and enables the use of domestic  separation standards of 5 nautical miles in this airspace. When this radar  is out of service, which happens on a regular basis, aircraft traversing the  airspace between Florida and Puerto Rico must be spaced using oceanic  separation standards (e.g., separation distances of 30 nautical miles or  greater). According to an industry report and FAA officials, this situation  leads to re-routes and delays, which negatively affect airline operations.  Using space-based ADS-B as a back-up surveillance system would  ensure that even when the Grand Turk radar fails, U.S. air traffic control  can continue to manage air traffic using domestic separation standards.

In 2021, once the operational evaluation is complete, the ASEPS program  expects to make recommendations to FAA executives on how to use  space-based ADS-B in the Miami oceanic flight region, in addition to other  areas. FAA officials also said that this evaluation will allow the agency to  test space-based ADS-B in an operational environment and that the  findings can inform its medium-term and long-term plans for using space- based ADS-B. The use of space-based ADS-B in this airspace could also  result in more direct routes between the U.S. East Coast and islands in  the Caribbean.

According to FAA officials and documentation, the ASEPS program  expects to study additional potential benefits of space-based ADS-B over  the next 3 to 5 years. These medium-term initiatives are expected to:

Analyze the use of space-based ADS-B for contingency  operations in U.S. airspace. This study would define where space- based ADS-B can be used to provide surveillance capabilities when  ground-based infrastructure (e.g., radar) is unavailable, such as after  a hurricane. As part of this plan, the ASEPS program would also  identify upgrades that would be needed for air traffic control computer  systems to support using space-based ADS-B.

Analyze operational challenges in U.S. oceanic airspace and  potential solutions. This study of U.S. oceanic airspace would  include a data-driven analysis of the use and constraints on the use of  user-preferred routes by aircraft in U.S. oceanic airspace. In addition  to providing information on potential inefficiencies in oceanic airspace  operations, the analysis will cover how to mitigate potential safety  hazards related to the use of space-based ADS-B in the oceanic  environment and the requirements for future upgrades to ATOP to  support the use of space-based ADS-B.

According to FAA officials, both medium-term initiatives would result in  recommendations for consideration by FAA executives in 2021. Using  space-based ADS-B for contingency operations could lead to updated air  traffic control procedures and computer upgrades; however, this would  depend on the results of the analysis and the approval of FAA executives.  The analysis of user-preferred routes in oceanic airspace could lead to  recommendations on how to optimize route systems and how to use  space-based ADS-B to support the use of user-preferred routes.

According to FAA officials and documentation, using space-based ADS-B  to enable the use of new minimum separation standards in U.S. oceanic  airspace will be reviewed and evaluated over the next 5 or more years.  This long-term initiative will use information learned through the near-term  and medium-term plans. As part of this initiative, the ASEPS program  intends to investigate options for enhanced communication technologies  and encourage industry development of these technologies. As with the  medium-term initiatives, the ASEPS program expects to make  recommendations to FAA executives on how to proceed with this plan in  2021. Based on the results of this initiative, program officials told us they  could start preparing for an investment decision on using space-based  ADS-B in oceanic airspace to enable the use of new minimum separation  standards in 2025 or later.

Selected Aviation Stakeholders Support FAA’s Overall Approach to Enhancing Surveillance and Identified Expected Benefits from Reducing Separation

Most Selected Airlines Support FAA’s Overall Approach to Enhancing Surveillance

Most (11 of 14) of the selected airlines we interviewed and surveyed  support FAA’s approach to enhance surveillance capabilities in U.S.  oceanic airspace by pursuing enhanced ADS-C and adopting new  minimum oceanic separation standards of 23 nautical miles lateral and 20  nautical miles longitudinal in the near term. Most (12 of 14) also support  continuing to evaluate how to use space-based ADS-B in oceanic  airspace. Of those selected airlines that did not support FAA’s approach,  the reasons included concern that using enhanced surveillance  technologies will increase operator costs with no clear benefits and that  FAA is prioritizing enhanced ADS-C over space-based ADS-B despite the  safety and technological advances the latter would enable.

While most selected airlines (12 of 14) were satisfied or very satisfied with  how FAA manages the safety of U.S. oceanic airspace, most noted the  need to improve operational efficiency in this airspace. Specifically, many  selected airlines (10 of 14) reported experiencing operational  inefficiencies, including not being able to fly at fuel-efficient altitudes.  Many of these airlines (9 of 10) view adopting new minimum separation  standards as a way to address these inefficiencies. Other aviation  stakeholders, including the unions representing FAA air traffic controllers  and commercial airline pilots, also see the need to enhance surveillance  and adopt new minimum separation standards to ensure that U.S.  oceanic airspace remains efficient as international air traffic grows.

Selected Airlines Identified Expected Benefits from FAA’s Implementation of New Minimum Oceanic Separation Standards

Selected airlines identified several benefits they would expect to see from  the implementation of new minimum oceanic separation standards,  including improved access to fuel-efficient altitudes, redesigned organized  track systems, and improved access to user-preferred routes.

Improved Access to Fuel- Efficient Altitudes

Most selected airlines (12 of 14) we surveyed view improved access to  fuel-efficient altitudes as a benefit of reduced separation standards.  Aircraft flying in controlled airspace cannot change altitudes (e.g., move  from 36,000 feet to 38,000 feet) without air traffic control approval. With  reduced minimum separation standards, air traffic control could grant  more altitude change requests, allowing aircraft to more consistently fly at  fuel-efficient altitudes. For example, representatives from one airline told  us that an aircraft’s ability to climb and descend as needed provides both  safety and operational benefits. Other airline representatives also told us  that the ability to fly at fuel-efficient altitudes results in savings on fuel  costs.

Many selected airlines (9 of 14) think FAA should make changes to  organized track systems once new minimum separation standards are  adopted. These changes include reducing lateral separation between  routes or removing the systems entirely to enable aircraft to fly user- preferred routes all the time.

Reduce lateral separation between the routes in organized track  systems. Currently, all organized track systems in U.S. oceanic  airspace have routes spaced at least 50 nautical miles apart laterally.  Several selected airlines (3) told us that they would expect FAA to  take advantage of new reduced minimum separation standards by  spacing routes more closely together. For example, representatives  from one airline suggested spacing the routes in the West Atlantic  Route System 30 nautical miles apart laterally—thus increasing the  number of routes from 10 to 19 and significantly increasing airspace  capacity. In a report prepared by the NextGen Advisory Committee’s  Enhanced Surveillance Task Group at the request of FAA, there was  also support for taking advantage of new minimum separation  standards enabled by enhanced surveillance to reduce the lateral  separation between routes in the Central East Pacific Route  System.

Remove all organized track systems. Several selected airlines (5 of  14) also viewed the adoption of new minimum separation standards  as a step toward the removal of all organized track systems.  Removing all organized track system routes would, by definition,  mean aircraft operators could fly user-preferred routes optimized  according to their preferences, such as fuel use and flight time. Air  navigation service providers in Canada and the United Kingdom,  which are responsible for managing the North Atlantic Organized  Track System, told us that the use of space-based ADS-B and the  proposed separation standards it supports (i.e., 19 nautical miles  lateral and 17 nautical miles longitudinal), may lead to the end of  published ATS routes for the North Atlantic Organized Track System.

Many selected airlines indicated that current separation standards inhibit  their ability to fly user-preferred routes (10 of 14) as well as their ability to  fly the most efficient user-preferred routes (11 of 14). Many selected  airlines (9 of 14) view more access to user-preferred routes or the ability  to fly more efficient user-preferred routes as an expected benefit of new  minimum separation standards. Several selected airlines (3 of 14) also  told us that they no longer request to fly user-preferred routes in the  airspace covered by the Central East Pacific Route System or along the  West Atlantic Route System because these requests are denied or they  are re-routed during the flight.

Selected airlines also noted the importance of understanding the costs,  benefits, and timelines associated with the implementation of enhanced  surveillance technologies in making their own investment decisions.  Specifically, most selected airlines (11 of 14) told us that their decision to  use an enhanced surveillance technology is contingent upon how much it  will cost them to implement the technology—which can involve equipping  aircraft and potentially paying subscription costs for the service— compared to the benefits airlines receive from the technology. For  example, representatives from one airline told us that they are interested  in the benefits of space-based ADS-B and enhanced ADS-C, but before  paying for new or additional surveillance services, they would need to  have evidence that the benefits of these services would outweigh the  costs. Specifically, the representatives would like to know to what extent  enhanced surveillance, if at all, would result in the actual use of new  minimum separation standards and the likelihood they would be able to  fly the flight plan they filed. With this information, the airline  representatives said the airline could determine whether they could  realize cost savings or additional revenue, such as through adding flights  to their schedules. Representatives from another airline told us they  would like to know what FAA’s plan is for enhancing surveillance and  enabling new minimum separation standards and to have assurance that  FAA will stick to this plan.

FAA Is Taking Steps to Realize the Benefits of New Minimum Oceanic Separation Standards

According to FAA officials and documents, the agency’s approach  addresses some of the efficiency benefits expected by airspace users.

Improved access to fuel-efficient altitudes. FAA officials and air  traffic controllers we spoke to expect the adoption of new minimum  separation standards to offer efficiency benefits to airspace users  through more consistent access to fuel-efficient altitudes. In a  business case analysis, FAA estimated that this benefit would result in  over $280 million in cost-savings for aircraft operators. According to  air traffic controllers we spoke to, with new minimum separation  standards they would be able to more frequently grant aircraft  requests to access these altitudes.

Redesign of organized track systems. When considering changes  to organized track systems, FAA officials said they must balance  benefits to airspace users with workload demands that would be  placed on air traffic controllers. FAA officials told us they are currently  redesigning the North Pacific Route System to take advantage of the  23 nautical mile lateral separation standard by reducing the lateral  separation between tracks. According to FAA officials, this redesign,  which is planned to be complete by 2021, could offer benefits to  aircraft operators flying between Japan and Alaska, such as allowing  air traffic to move more efficiently and with fewer restrictions on user- preferred routes. FAA officials told us that redesigning the North  Pacific Route System is possible because of high FANS-equipage  rates (over 95 percent) and the absence of disruptive weather  patterns. However, according to FAA officials, they do not plan any  changes to other organized track systems, such as the Central East  Pacific Route System and the West Atlantic Route System, at this  time because of aircraft equipage rates and weather patterns. In such  areas, moving the routes closer together would prevent air traffic  controllers from approving aircraft requests to deviate due to bad  weather.

Access to user-preferred routes. FAA officials differ with selected  airline representatives on whether reduced separation standards  would lead to increased access to user-preferred routes. According to  FAA officials and documents, improved access to user-preferred  routes requires an increase in aircraft equipped with FANS, not  changes to the airspace. FAA officials also said that airlines can fly  user-preferred routes in the Central East Pacific Route System and  the West Atlantic Route System but also acknowledged that air traffic  controllers often cannot grant access to user-preferred routes in these  airspaces because of the volume of air traffic or disruptive weather  patterns. Given the differing perspectives and limited data on user- preferred routes, in April 2019, FAA decided to engage a third-party  research company to study the use of and access to user-preferred  routes in U.S. oceanic airspace, to be completed in late 2021. Based  on this study, FAA may investigate changes to U.S. airspace to  address problems identified.

FAA identified venues to share and coordinate their enhanced  surveillance plans, timelines, and expectations with aviation industry  stakeholders. As previously noted, FAA’s process for implementing  changes to separation standards requires the agency to coordinate with  and brief domestic and international aviation industry stakeholders. FAA  officials also pointed to other venues where they plan to share information  on these plans with airlines, including formal and informal working groups.  Given the relatively early stages of the implementation of the 23 nautical  mile lateral and 20 nautical mile longitudinal separation standards  enabled by enhanced ADS-C, FAA has not yet completed this industry  outreach. The agency plans to coordinate with the aviation industry on the  implementation of these separation standards by January 2021.

Selected Airlines and Other Aviation Stakeholders Raised Concerns about Two Possible Consequences of FAA’s Approach to Enhanced Surveillance

Several selected airlines and other aviation stakeholders—representing  pilots, commercial airlines, business aircraft operators, and general  aviation—noted the importance of FAA taking advantage of technology  advancements and benefits that space-based ADS-B can offer. For  example, several (5) selected airlines view space-based ADS-B as a  major advancement in oceanic surveillance. Representatives from one  airline told us that FAA risks losing its position as a global leader if it does  not move forward with space-based ADS-B and the reduced separation  standards it enables.

According to FAA officials, the agency is a leading air navigation service  provider as demonstrated by its use of advanced computer systems to  apply minimum separation standards when possible, its role in developing  ICAO’s new minimum separation standards, and its plans to move  forward with space-based ADS-B in a manner that best fits U.S. oceanic  airspace needs. FAA officials also pointed to other air navigation service  providers, such as the Japan Civil Aviation Bureau, that are not currently  planning to use space-based ADS-B.

Harmonization with Adjacent Flight Regions

Several selected airlines and other aviation stakeholders representing  commercial and business airlines expressed concern that by not adopting  enhanced surveillance and the minimum separation standards it enables,  aircraft transitioning into and out of U.S. oceanic airspace could  experience delays. Representatives of the Canadian and United Kingdom  air navigation service providers, which began using space-based ADS-B  and the new minimum separation standards it enables in 2019, told us  that different separation standards between their oceanic airspace and  U.S. oceanic airspace could lead to delays for aircraft as air traffic  increases. Specifically, as air traffic grows and air traffic controllers  apply separation distances closer to the minimum standards, those flight  regions with lower minimum standards will have to space out aircraft  crossing into flight regions with higher minimum separation standards  prior to an aircraft crossing a flight region boundary. This situation could  lead to delays crossing flight region boundaries and less access to  efficient routes across oceanic airspace.

FAA views other factors, such as the low volume of air traffic in some  airspaces, the frequency of disruptive weather patterns, and the relatively  low percentage of aircraft equipped with FANS in high volume airspaces,  to contribute more to the operational efficiency of the oceanic airspace  than the use of minimum standards. As previously noted, according to  FAA officials and air traffic controllers, the current minimum separation  standards for U.S. oceanic airspace (30 nautical miles lateral and  longitudinal) are rarely used because of these factors. In addition, FAA  officials told us that the difference between the separation standards FAA  plans to adopt in U.S. oceanic airspace with enhanced ADS-C (23  nautical miles lateral and 20 nautical miles longitudinal) and the  separation standards enabled by space-based ADS-B (19 nautical miles  lateral and 17 nautical miles longitudinal) is unlikely to result in delays  even as air traffic increases.

Other air navigation service providers in the Atlantic and Pacific Oceans  are still assessing the costs and benefits of space-based ADS-B. For  example, the Portuguese air navigation service provider told us they are  still considering whether to use space-based ADS-B. In the Pacific  Ocean, the Japanese air navigation service provider has not decided  whether to use space-based ADS-B and therefore will not be adopting the  minimum separation standards (19 nautical miles lateral and 17 nautical  miles longitudinal) enabled by this technology. While the Japanese plan  to adopt the 23 nautical mile lateral separation standard supported by  enhanced ADS-C, they do not plan to adopt the 20 nautical mile  longitudinal separation standard at this time.

We provided a draft of this report to the Department of Transportation  (DOT) for review and comment. DOT responded by email and provided  technical clarifications, which we incorporated into the report as  appropriate.

We are sending copies of this report to the appropriate congressional  committees, the Secretary of the Department of Transportation, and other  interested parties. In addition, the report is available at no charge on the  GAO website at http://www.gao.gov.

If you or your staff have any questions about this report, please contact  me at (202) 512-2834 or krauseh@gao.gov. Contact points for our Offices  of Congressional Relations and Public Affairs may be found on the last  page of this report. GAO staff who made key contributions to this report  are listed in appendix VI.

Appendix I: Objectives, Scope, and Methodology

This report examines (1) the Federal Aviation Administration’s (FAA)  approach to enhancing surveillance capabilities to improve safety and  efficiency in U.S. oceanic airspace and (2) selected aviation stakeholders’  perspectives on FAA’s approach to enhancing surveillance.

To address both of our objectives, we reviewed FAA and other aviation  stakeholders’ documents on the management and organization of U.S.  oceanic airspace; the functionality and use of communication, navigation,  and surveillance equipment in aircraft flying in U.S. oceanic airspace; and  descriptions of the enhanced surveillance technologies that were being  considered by FAA—space-based Automatic Dependent Surveillance- Broadcast (ADS-B) and enhanced Automatic Dependent Surveillance- Contract (ADS-C). Specifically, to understand how U.S. air traffic  controllers manage oceanic airspace and the procedures aircraft  operators must follow, we reviewed FAA Advisory Circulars on Oceanic  and Remote Continental Airspace Operations (91-70B) and Data Link  Communications (90-117) and FAA Order JO 7110.65X: Air Traffic  Control. We also reviewed a NextGen Advisory Committee report,  Enhanced Surveillance Capabilities in FAA Controlled Oceanic Airspace:  Operational Need and Added Benefits, that was prepared at the request  of FAA on this topic, to understand the industry perspective on the need  for enhanced surveillance in U.S. oceanic airspace and the costs and  benefits of using space-based ADS-B. To understand how space-based  ADS-B and enhanced ADS-C would function, we interviewed  representatives from Aireon, which offers the space-based ADS-B  service, and Inmarsat, which provides the primary satellite communication  network used by the providers of ADS-C services.

We also interviewed other aviation industry stakeholders, including trade  associations representing aircraft operators and unions representing  pilots, including Airlines for America, International Air Transport  Association, National Air Carrier Association, National Business Aviation  Association, Aircraft Owners and Pilots Association, Coalition of Airline  Pilots Associations, and Air Line Pilots Association. These organizations  were selected based on several factors: their inclusion in prior GAO  reports, their role in the aviation industry, and recommendations from  other industry stakeholders or FAA.

To examine FAA’s approach to enhancing surveillance capabilities in U.S.  oceanic airspace, we reviewed FAA documents and interviewed FAA  officials. The documents we reviewed included those related to FAA’s  plans to modernize management of oceanic airspace, specifically The  Future of the National Airspace System (June 2016) and National  Airspace System Capital Investment Plan FY2018-2022. We also  reviewed FAA’s policy guidance on acquisitions and investment  documents related to the Advanced Surveillance Enhanced Procedural  Separation (ASEPS) program’s planned investment decision on  enhanced surveillance. These internal FAA documents included the  ASEPS Concept of Operations, the Initial and Final Business Case  Analyses, the Final Investment Decision Benefits Basis of Estimate, and a  Safety Risk Management Assessment of space-based ADS-B and  enhanced ADS-C. In reviewing the business case analysis, we did not  independently evaluate the methodology or data sources used.

We interviewed FAA officials and program managers that are working on  different elements of FAA’s efforts to enhance surveillance in U.S.  oceanic airspace. Within the Air Traffic Organization, we interviewed  officials from several offices, including the ASEPS program, which  managed the evaluation of surveillance technologies; the  Oceanic/Offshore Standards and Procedures Branch, which oversees air  traffic operations in oceanic airspace such as facilitating changes to air  traffic procedures and systems to enable the use of new technologies and  new standards; and the Advanced Technologies and Oceanic Procedures  Program Office, which oversees changes to the air traffic control  computer system used to manage oceanic air traffic. We also interviewed  FAA officials with the Flight Standards Service, which works to improve  flight operations, standardization, and aviation safety across U.S. and  international airspace systems. In addition, we interviewed the contractor  who prepared FAA’s business case analyses.

We interviewed FAA air traffic controllers at the Anchorage, New York,  and Oakland air route traffic control centers, which are responsible for  managing the flight information regions that comprise U.S. oceanic  airspace. In addition, we conducted site visits to the New York and  Oakland air route traffic control centers, where we observed air traffic  controllers providing oceanic air traffic services. We also interviewed  representatives from the National Air Traffic Controllers Association,  which is the union representing FAA air traffic controllers. We also  interviewed or received written responses from representatives of the air  navigation service providers for oceanic airspace adjacent or close to  U.S. oceanic airspace—Canada, Japan, Portugal, and the United  Kingdom—to understand their plans to enhance surveillance capabilities.

To obtain selected aviation stakeholders’ perspectives on FAA’s  approach to enhancing surveillance in U.S. oceanic airspace, we selected  10 U.S. and foreign commercial airlines using FAA data from fiscal year  2016 on the annual number of flights by airline in U.S. oceanic flight  information regions–Anchorage Arctic and Oceanic, Oakland Oceanic,  and New York Oceanic. Specifically, we selected the five airlines in each  U.S. oceanic flight information region with the most annual flights. Some  airlines were in the top five in more than one flight information region. All  10 airlines selected using this method were passenger airlines. We  selected an additional passenger airline because it planned to begin  service in U.S. oceanic airspace. We selected three large cargo airlines,  based on tons of cargo transported, to ensure that the cargo airlines’  perspective was represented. Of the 14 airlines we selected, we  conducted semi-structured interviews with or received written responses  to our questions from 13.

To obtain additional information from airline operators, we conducted a  follow-up survey of the 14 selected airlines. The survey included  questions on perceptions of the safety of FAA’s management of U.S.  oceanic airspace, operational inefficiencies experienced by airlines in  U.S. oceanic airspace, effect of current separation standards on airlines’  use of user-preferred routes, airlines’ expectations of the benefits of  reduced separation standards, and airlines’ support for FAA’s planned  approach to enhance surveillance in oceanic airspace. We developed the  survey based on our objectives and included topics not covered in our  initial interviews. We pre-tested our survey with representatives of three  of the 14 selected airlines. We conducted the survey between December  2018 and January 2019, and all 14 selected airlines completed the  survey. For the complete list of airlines we interviewed and/or surveyed,  see table 1.

In this report, we use the following conventions in reference to information  obtained from the 14 selected airlines: “several” is three to seven, “many”  is eight to 10, and “most” is 11 to 13.

We conducted this performance audit from March 2018 to July 2019 in  accordance with generally accepted government auditing standards.  Those standards require that we plan and perform the audit to obtain  sufficient, appropriate evidence to provide a reasonable basis for our  findings and conclusions based on our audit objectives. We believe that  the evidence obtained provides a reasonable basis for our findings and  conclusions based on our audit objectives.

Appendix II: Current and Proposed Separation Standards for Oceanic Airspace

Current and Proposed Minimum Separation Standards for Oceanic Airspace

The International Civil Aviation Organization (ICAO) publishes minimum  separation standards and related eligibility requirements for oceanic  airspace. Air navigation service providers, such as the Federal Aviation  Administration (FAA), may adopt these standards or apply standards that  are more conservative (e.g., require greater distances between aircraft).  Table 1 lists selected ICAO current and proposed minimum separation  standards for oceanic airspace that rely on either Automatic Dependent  Surveillance-Contract (ADS-C) or space-based Automatic Dependent  Surveillance-Broadcast (ADS-B).

Separation Standards Commonly Applied in U.S. Oceanic Airspace

The lateral and longitudinal separation standards commonly applied by  U.S. air traffic controllers in U.S. oceanic airspace—the Anchorage Arctic,  Anchorage Oceanic, New York Oceanic, and Oakland Oceanic flight  regions—are shown in table 2.

Aircraft meeting these communication, navigation, and surveillance  equipment and performance requirements are eligible for the separation  standards detailed above. However, the actual standards applied by U.S.  air traffic controllers depend on several factors, including the number of  similarly eligible aircraft and air traffic volume. For example, while an  aircraft may be eligible to use the 30 nautical mile lateral separation  standard, nearby aircraft may not. When aircraft with differing  communication, navigation, and/or surveillance capabilities are flying near  one another, air traffic controllers must apply the larger separation  standard based on the aircraft with the fewest capabilities.

Air traffic controllers consider not just an aircraft’s current location but  also where it is going when applying separation standards. Therefore, as  aircraft approach the boundaries of U.S. oceanic airspace, U.S. air traffic  controllers also consider the separation standards and eligibility  requirements of the neighboring flight region. Based on our interviews,  U.S. air traffic controllers hand off aircraft to their foreign counterparts  (and vice versa) so that aircraft enter a new flight region in conformance  with that flight region’s standards. For example, air traffic controllers  managing aircraft in the Anchorage Oceanic flight region do not typically  space aircraft heading towards Russian oceanic airspace (the Magadan  Oceanic Flight Information Region) at the minimum separation—even if  they are eligible. According to these air traffic controllers, any benefits  that aircraft would gain from flying at the minimum separation distance in  U.S. airspace would be lost when entering Russian airspace, where the  separation standards are 10 minutes longitudinal (approximately 80  nautical miles). Therefore, aircraft must be spaced at least 10 minutes  apart longitudinally upon entering Russian airspace.

As shown in tables 1 and 2 above, FAA uses the 30 nautical mile  longitudinal standard but does not use the 23 nautical mile lateral  standard. According to interviews with FAA officials and FAA  documentation, FAA plans to adopt and start using the 23 nautical mile  lateral standard in U.S. oceanic airspace in 2021 and the 20 nautical mile  longitudinal standard in this airspace in 2022. According to FAA officials,  the agency does not plan to adopt the other ICAO proposed minimum  standards (i.e., 19 or 15 nautical miles lateral and 17 or 14 nautical miles  longitudinal) that depend on the use of space-based ADS-B at this time.

Appendix III: Acquisition Steps Completed by the Advanced Surveillance Enhanced Procedural Separation (ASEPS) Program

The Federal Aviation Administration (FAA) Acquisition Management  System (AMS) policy outlines a process for evaluating potential  investments. This process includes the following milestones:  1.  definition of the concept and requirements of a program;  2.  investment analysis readiness decision;  3.  initial investment decision (business case analysis to determine the  4.  final investment decision (final business case and implementation  5.  solution implementation (program implementation).

FAA’s corporate-level acquisition decision-making body—the Joint  Resources Council (JRC) —approves or disapproves at each AMS  milestone. If the JRC approves the final investment decision, this commits  FAA to funding the program segment and moving forward with the  investment plan.

From January 2014 to April 2019, FAA’s Advanced Surveillance  Enhanced Procedural Separation (ASEPS) program—tasked with  evaluating and comparing the costs and benefits of enhanced Automatic  Dependent Surveillance–Contract (ADS-C) and space-based Automatic  Dependent Surveillance–Broadcast (ADS-B)—progressed through the  following steps in the AMS process to prepare for a final investment  decision on enhancing surveillance and enabling new minimum  separation standards in U.S. oceanic airspace.

January 2014 (investment analysis readiness decision). JRC  approved FAA to begin further analysis of options, including enhanced  ADS-C and space-based ADS-B to support the adoption of reduced  separation standards in U.S. oceanic airspace. As part of this  analysis, FAA took the following actions.

July 2015. JRC recommended that the ASEPS program continue  evaluating the space-based ADS-B option to accommodate user  (i.e., airline) preference.

July 2016. FAA tasked the NextGen Advisory Committee with  evaluating (1) the need and benefit of enhanced surveillance  capabilities, including associated costs, funding mechanisms and  funding models and (2) evaluate the business case, including  insight regarding several operational factors impacting potential  benefits from an investment. FAA requested input from the  NextGen Advisory Committee to better understand industry’s  assessment of (1) the quantified benefit that industry expects the  investment will deliver and (2) how much industry would be willing  to pay if it was responsible for the investment. However, according  to FAA officials, the report did not address the quantified benefit  industry expects the investment will deliver, determine how much  industry would be willing to pay if it was responsible for the  investment, or conduct an overall assessment of whether the  investment is cost beneficial to industry. The report cited not  having sufficient information, such as expected benefits and costs,  to conduct an analysis of how much industry would be willing to  invest.

October 2017 (initial investment decision). ASEPS Program  presented the initial business case analysis comparing the two  enhanced surveillance options, enhanced ADS-C and space-based  ADS-B, to the JRC. Given the negative return on investing in space- based ADS-B, the JRC directed the ASEPS program to evaluate the  costs and benefits of space-based ADS-B within sub-sectors of U.S.  oceanic flight regions, such as Oakland flight region north and New  York east.

March 2018. JRC directed the ASEPS Program to proceed with  both enhanced surveillance options—enhanced ADS-C and  space-based ADS-B—to a final investment decision, which was  planned for September 2018.

June 2018. ASEPS Program proposed a strategic shift, which  involved delaying the final investment decision on enhanced ADS- C and deferring a final investment decision on space-based ADS- B to allow additional testing on how to use space-based ADS-B in  oceanic and domestic airspace. Drivers of this shift in approach  included the results of the business case analysis.

September 2018 (strategy decision). JRC approved the ASEPS  program’s strategic shift.

The ASEPS Program asked the JRC to approve their plan to  delay a final investment decision on enhanced ADS-C and to  defer a final investment decision on space-based ADS-B.

The JRC approved the ASEPS program’s proposal to merge the  ASEPS enhanced ADS-C investment with a planned final  investment decision on upgrades to the Advanced Technology  and Oceanic Procedures (ATOP) system.

The JRC also approved the ASEPS program’s proposal to  continue studying space-based ADS-B through an operational  evaluation in U.S. offshore airspace and longer-term studies  concerning using space-based ADS-B for contingency operations  and future use in U.S. oceanic airspace.

April 2019 (final investment decision). JRC approved a final  investment decision on the ASEPS Program’s plan to use enhanced  ADS-C to enable new minimum separation standards in U.S. oceanic  airspace.

The ATOP program management office asked the JRC to approve  investments in large-scale ATOP enhancements that include  system changes that will enable the implementation of new  minimum separation standards (i.e., 23 nautical miles lateral and  20 nautical miles longitudinal) with the use of enhanced ADS-C.

Appendix IV: Costs and Benefits in the Advanced Surveillance Enhanced Procedural Separation (ASEPS) Business Case Analysis

As part of its acquisition process (outlined in app. III), the Federal Aviation  Administration (FAA) contracted with a third-party to prepare a business  case analysis for the Advanced Surveillance Enhanced Procedural  Separation (ASEPS) program. This analysis estimated the costs to the  agency and aircraft operators, identified safety benefits from enhanced  surveillance, and identified and calculated the value of efficiency benefits  from applying new minimum separation standards enabled by two  technologies: enhanced Automatic Dependent Surveillance-Contract  (ADS-C) and space-based Automatic Dependent Surveillance-Broadcast  (ADS-B). The analysis described below was developed for FAA’s initial  and final investment decision on the program:

ASEPS Initial Business Case (August 2017). This business case  analysis compared the costs and benefits of space-based ADS-B and  enhanced ADS-C to a baseline scenario.

ASEPS Final Business Case (August 2018). This business case  analysis compared the costs and benefits of enhanced ADS-C to a  baseline scenario. No final business case analysis was prepared for  space-based ADS-B since FAA deferred a final investment decision  on the use of space-based ADS-B.

This appendix discusses the costs and benefits that were included in  these business case analyses based on our review of FAA’s business  case documentation and interviews with FAA officials.

Description of Baseline, Enhanced ADS-C, and Space- based ADS-B Scenarios

In the initial business case, a baseline scenario and two alternative  scenarios were used to evaluate the costs and benefits of using  enhanced ADS-C and space-based ADS-B as compared to not using  these enhanced surveillance options: baseline with no change in current minimum separation standards of  30 nautical miles lateral and 30 nautical miles longitudinal, use enhanced ADS-C with minimum separation standards of 23  nautical miles lateral and 23 nautical miles longitudinal, and use space-based ADS-B with minimum separation standards of 15  nautical miles lateral and 15 nautical miles longitudinal.

In the final business case analysis, only a baseline scenario and the  enhanced ADS-C scenario were included.

In the business case analysis, costs and benefits were modelled between  2020 and 2040 in the Atlantic and Pacific Oceans. To model these  scenarios, researchers used projections on flight demand and aircraft  equipage with the technology required to use these enhanced  surveillance services: Future Air Navigation System (FANS) or ADS-B  and FANS.

In order to use enhanced ADS-C and space-based ADS-B to enable new  minimum separation standards, FAA and airspace users will need to  make certain investments. Based on our review of FAA’s business case  documentation, we found that certain costs were factored into the  business case analysis, including: upgrades to the Advanced Technologies and Oceanic Procedures additional ADS-C message traffic, and  subscription fee for space-based ADS-B service  The final business case analysis focused on enhanced ADS-C and  included only those costs to FAA and users related to use of this service.

The business case analysis focused on the costs of these enhanced  surveillance services and did not include the cost of equipping aircraft  with FANS and/or ADS-B equipment, which are required to use these  enhanced surveillance technologies. According to FAA officials, these  costs were not included because aircraft operators are equipping their  aircraft for other reasons. Specifically, FAA regulations requiring ADS-B  equipment for aircraft flying through U.S. domestic airspace by 2020  means most aircraft flying in U.S. oceanic airspace will be ADS-B  equipped. In addition, mandates from other air navigation service  providers requiring FANS will compel most aircraft crossing into non-U.S.  oceanic airspace to equip with FANS.

The business case considered the costs FAA would incur using the data  from these enhanced surveillance technologies, including upgrades to  ATOP software.

The business case analysis also considered the costs airspace users  would face in using these enhanced surveillance technologies. In the  business case analysis, FAA assumed that aircraft operators would  continue to pay for ADS-C services. Since enhanced ADS-C would  involve more messages per flight hour than currently sent via ADS-C,  FAA estimated that aircraft operators would see an increase in  messaging costs per flight hour, according to our review of FAA  documentation. FAA also made assumptions about how much a  subscription fee for space-based ADS-B will cost. As a new service that  FAA has not yet contracted for, the actual cost of space-based ADS-B  subscription fees are not known. However, initial estimates of the cost per  flight hour for space-based ADS-B are much greater than the estimated  cost per flight hour of additional ADS-C messages, according to FAA.

FAA’s business case analysis considered safety benefits and efficiency  benefits. As detailed in the analysis, the size of these benefits depends  on the participation of aircraft in each enhanced surveillance service (i.e.,  enhanced ADS-C and space-based ADS-B). The benefits presented in  the business case represent the maximum benefit pool. Specifically, the  analysis assumes that all properly equipped aircraft will use space-based  ADS-B or enhanced ADS-C services.

The business case analysis discussed safety benefits offered by  improved surveillance, such as increased air traffic controller situational  awareness and improved detection and resolution of aircraft on conflicting  flight paths. According to oceanic air traffic controllers we interviewed at  the three air route traffic control centers responsible for U.S. oceanic  airspace, enhancing surveillance capabilities offers safety benefits, such  as improved situational awareness and search and rescue capabilities.  Enhanced ADS-C and space-based ADS-B both offer these safety  benefits. However, space-based ADS-B also provides information to air  traffic controllers to reduce the risk of a vertical collision between aircraft.  This safety benefit was monetized by FAA.

Enhanced surveillance can enable a reduction in the minimum required  distance applied between aircraft, with potential efficiency benefits for  airspace users. The three efficiency benefits included in FAA’s business  case analysis that were monetized are:  Improved accommodation of altitude requests. According to FAA’s  analysis, a primary benefit of reduced separation standards is that  aircraft will be more likely to fly at a fuel-efficient altitude. In oceanic  airspace, aircraft must make a request to air traffic control to change  their altitude. Despite the immensity of oceanic airspace, there is  competition for the most fuel-efficient altitudes at certain times of day.  For example, according to oceanic air traffic controllers in Oakland,  the majority of the air traffic they handle is flights between Hawaii and  the U.S. west coast, with most aircraft departing at the same time. Air  traffic controllers we spoke with agreed that with enhanced  surveillance and reduced separation standards, they should be able to  grant more altitude requests and allow more aircraft to fly at optimal  altitudes.

Reduced need for aircraft to carry extra fuel. According to FAA’s  analysis, aircraft operators typically carry more fuel on an aircraft than  needed to fly their planned route. Aircraft carry extra fuel to hedge  against the possibility that its actual flight path will be less fuel-efficient  than its planned flight path. The cost of carrying extra fuel (i.e., the  cost to carry) comes from the added weight of carrying extra fuel,  weight that causes an aircraft to use more fuel and that reduces an  aircraft’s ability to carry revenue-generating cargo. This benefit flows  from the improved accommodation of altitude requests, discussed  above.

More efficient arrivals and departures at Pacific island airports.

According to FAA’s analysis, some Pacific island airports do not have  radar surveillance and require U.S. oceanic air traffic controllers in the  Oakland air route traffic control center to manage aircraft arrivals and  departures. As a result, oceanic separation standards are applied as  aircraft arrive and depart these islands’ airports. FAA’s analysis shows  that reducing oceanic separation minimums will allow air traffic  controllers to allow more frequent arrivals and departures from these  airports. According to this analysis, the benefit of more frequent  arrivals and departures is measured in terms of the costs to aircraft  operators (an aircraft’s direct operating costs) and the cost to  passengers (a passenger’s value of time).

FAA’s business case analysis also includes efficiency benefits of reduced  separation that were not monetized, including emissions savings and  improved air traffic control accommodation of aircraft requests for  descents, routing changes, and speed changes. FAA policy does not  currently allow programs to value carbon dioxide emissions avoided for  investment decisions. Another efficiency benefit of reduced separation— giving air traffic controllers more flexibility to grant deviations from  planned flight paths due to disruptive weather—was quantified and  monetized, but not factored into the benefit calculation.

Appendix V: Federal Aviation Administration’s 18 Critical Milestones to Implement a New Separation Standard

To implement new separation standards in U.S. oceanic airspace, the  Federal Aviation Administration (FAA) has a set of 18 critical milestones  that it follows:  1.  Determine the operational need.  2.  Evaluate the benefits.  3.  Establish an operational concept.  4.  Assess the impact on air traffic control.  5.  Conduct a safety assessment and record it with the appropriate safety  risk management documentation.  6.  Determine requirements.  7.  Conduct a feasibility and economic analysis.  8.  Establish requirements for aircraft and operator approval.  9.  Conduct rulemaking.  10. Coordinate with industry and international participants.  11. Coordinate with air traffic control representatives and pilot groups.  12. Complete regional documentation.  13. Acquire approval for aircraft and operators.  14. Develop pilot and air traffic control procedures.  15. Design pilot and air traffic control training materials.  16. Confirm that the system works.  17. Employ the separation standard.  18. Monitor the performance of the system in accordance with safety risk  management practices.

Appendix VI: GAO Contact and Staff Acknowledgments

In addition to the contact named above, Jonathan Carver (Assistant  Director), Sarah Arnett (Analyst-in-Charge), Amy Abramowitz, Melissa  Bodeau, Samuel Gaffigan; David Hooper, Richard Hung, Amanda Miller,  Malika Rice, and Pamela Vines made key contributions to this report.

International aviation standards are changing to allow aircraft flying above an ocean to fly closer to each other. Air traffic controllers can apply the new standards in the airspace they manage if they use certain flight surveillance technologies. If not, aircraft must continue to fly farther apart—using less direct routes that aren’t as fuel efficient.

The FAA evaluated two such surveillance technologies and committed to using one of the technologies by 2022. It will continue to study the other.

Most of the commercial airlines we interviewed agreed with FAA’s approach.