Air Traffic Services Brief -- Automatic Dependent Surveillance-Broadcast (ADS-B)

Air Traffic Services Brief

Automatic Dependent Surveillance-Broadcast (ADS-B)

The issue:

A major component of the Federal Aviation Administration’s (FAA) Next Generation Air Transportation System (NextGen) modernization initiative is the complete overhaul of radar surveillance. The FAA is deploying a relatively new technology called Automatic Dependant Surveillance-Broadcast (ADS-B), where aircraft equipped with Global Positioning System (GPS) receivers can transmit their location and altitude to other nearby aircraft and to air traffic control. Although the FAA plans to retain primary radar for homeland defense purposes, many of today’s secondary surveillance radars will be shut down in the future.

On May 27, 2010 the FAA issued a final rule mandating Automatic Dependant Surveillance –Broadcast (ADS-B) equipage. Effective on January 1, 2020, any aircraft operating in airspace where a Mode C transponder is required today, will also be required to carry an ADS-B OUT transmitter. The FAA is not mandating ADS-B IN systems with this rule.

The rule does not impact the current transponder requirement – meaning aircraft will continue to be required to carry their transponders in addition to this requirement for ADS-B Out equipage after 2020.

Unlike most rulemaking activities which are safety based, the basis of the mandate is to support the FAA’s Next Generation Air Transportation System (NextGen). The FAA indicates that the mandate will not greatly increase or decrease safety, but is necessary to move forward with NextGen.

The Importance to our Members:

The ADS-B mandate will likely affect most of the AOPA membership. There are a myriad of issues surrounding the mandate and the infrastructure deployment strategy. If implemented properly, ADS-B could be beneficial to general aviation, but at this time many hurdles exist that could prevent ADS-B from being either affordable or beneficial in the near term.

AOPA is working closely with the FAA to ensure that, over the next 10 years, pilots can easily identify benefits of ADS-B and equip with affordable avionics, and not simply to comply with new rules.

Background

Since 1990 AOPA members have embraced Global Positioning System (GPS) technology and ADS-B has been part of the long-term modernization initiative at the FAA. Since 1999, AOPA has carefully evaluated ADS-B in an effort to confirm the potential benefits of ADS-B. By working closely with general aviation pilots in a wide-spread ADS-B trial and demonstration in Alaska, and by equipping the AOPA fleet of aircraft with ADS-B, we have seen first-hand the safety and efficiency improvements that are possible, if the system is designed and implemented correctly.

In 2007 the FAA launched their nationwide deployment, and proposed mandatory equipage. AOPA immediately identified a number of significant issues that would likely reduce or eliminate the benefits of ADS-B for general aviation, and we have been working to educate and encourage the FAA to make programmatic and regulatory adjustments that result in reduced avionics costs and increased benefits.

AOPA’s Position

For nearly 20 years AOPA has supported the transition from ground-based infrastructure to satellite based systems. AOPA generally supports ADS-B in concept, if the members can easily identify tangible benefits to their operation.

However at this time, is difficult to identify adequate benefits in the ADS-B implementation strategy. AOPA expects members to delay equipage until they are forced to comply with the mandate. However, we remain optimistic that over the next decade, safety concerns will be mitigated, avionics prices will drop, and general aviation benefits will emerge. As identified in comments to the FAA, there are a number of concerns with FAA’s proposed implementation strategy to include:

  • Collision risk. The FAA is implementing ADS-B on two independent, non-compatible frequencies. Unless general aviation pilots equip aircraft in such a way that they receive the ADS-B transmissions on both frequencies, they will likely see only one-half of the ADS-B equipped fleet. The costs and availability of dual-frequency ADS-B receiver is not known. The FAA could address this concern in two ways, 1) either provide a re-broadcast service at all general aviation airports or 2) require all aircraft to transmit on the same frequency.
  • Mandate not necessary. AOPA recommended that the FAA exclude low-altitude operators from the mandate because the financial benefits all stem from operations in high altitude airspace, over the Gulf of Mexico, or when operating to/from the largest airline airports. An independent FAA sanctioned rulemaking committee confirmed the AOPA recommendation would achieve most of the benefits without the widespread mandate on general aviation. More information will become available when the FAA publishes the regulations mandating ADS-B.
  • Affordability. AOPA has recommended several technical changes that would reduce the price of ADS-B systems. AOPA has also called on the FAA to permit pilots to use hand-held ADS-B receivers that can obtain free traffic, weather and airspace status content from the ADS-B infrastructure.
  • Transponder removal. AOPA recommended that because the FAA plans to transition from radar and transponders to ADS-B, that general aviation aircraft should be allowed to remove their transponders. However, the FAA has rejected that proposal, primarily because they have not adapted Traffic Collision Avoidance System (TCAS) to support ADS-B.
  • ADS-B infrastructure. The FAA is installing ADS-B infrastructure to provide the same coverage as radar. Except for overwater, deep in the Gulf of Mexico, no new airspace or airports are expected to receive surveillance as a result of the ADS-B infrastructure installation. Therefore, except when operating near major metropolitan areas, general aviation will largely operate underneath or outside ADS-B coverage. AOPA has called on the FAA to expand ADS-B coverage to include general aviation airports. A broad coalition of the industry has embraced AOPA’s recommendation, but the FAA has yet to respond.

Status / Next Steps for ADS-B

The FAA published the Final Rule mandating ADS-B out effective January 1. 2020.  The infrastructure installations are underway nationwide and by 2013, nearly 800 ground stations will be capable of receiving ADS-B signals from aircraft.

Over the next ten years AOPA expects several avionics manufacturers to introduce first-generation avionics systems that comply with the mandate requirements. AOPA also expects some of the ADS-B systems to be capable of receiving ADS-B data, and depicting the traffic information on a multi-function display in the cockpit.

ADS-B ground stations are transmitting Traffic Information Services-Broadcast (TIS-B), which is radar-derived traffic uplinked to ADS-B equipped aircraft. The ground stations are also transmitting Flight Information Services Broadcast (FIS-B) data with no subscription charge. Pilots who equip with ADS-B systems capable of receiving the TIS-B and FIS-B will experience the sole benefit that AOPA has identified in the current FAA implementation strategy.
For more information, see the FAA ADS-B main page or the FAA ADS-B map of available coverage.