Friday, June 6, 2008

NextGen 301: Automatic Dependent Surveillance

Welcome to Wired!

Having discussed Performance-based Navigation and Satellite Based Augmentation Systems we've explored the technology and regulatory enhancements that air traffic control agencies are developing in order to moderate aircraft transitioning national and international airspace. It has quickly been proven that these changes to the regulatory environment when coupled with advanced navigation aid aloft that operators and controllers can achieve maximized utilization of what is already densely populated airspace. But what technology and methodologies exist to allow the greatest efficiency to the operators and controllers as they consume more and more airspace resources? Automatic Dependent Surveillance

Automatic Dependent Surveillance is a crucial component of the nation's Next-Generation Air Transportation System, and its implementation over the next 20 years will turn the NextGen vision into a reality. There are three classifications of Automatic Dependent Surveillance technology: Address (ADS-A); Broadcast (ADS-B); Contract (ADS-C). ADS-B is the prevailing component of this technology and has taken the early lead in forging the lead of this new technology.

Automatic Dependent Surveillance - Addressed (ADS-A) is a capability where aircraft are equipped to determine their own position automatically and to broadcast this information to specific addressees of listeners whether on the ground or aloft. The technology is good; however, its overall effectiveness is limited to those addresses specifically called-to by the ADS-A operator.

Automatic Dependent Surveillance - Broadcast (ADS-B) is a capability where aircraft are equipped to determine their own position automatically and to broadcast this information to interested listeners at regular time intervals. Recipients of the broadcast position information are other nearby aircraft and ground ATC systems.

Automatic Dependent Surveillance – Contract (ADS-C) is an operational precept that enforces the ground system to set up a contract(s) with individual aircraft such that the aircraft will automatically provide information obtained from its own on-board sensors, and pass this information to the ground system under specific circumstances dictated by the ground system (except in emergencies). Contracts are only initiated by the ground and cannot be modified by the pilot. These contracts are an electronic 'dynamic agreement' between the ground system and the aircraft. It is not (as one could think) a piece of paper that has some legal value.

Rulemaking Sidebar: RTCA DO-212 [Minimum Operational Performance Standard (MOPS) for Airborne ADS equipment] Compliance with this standard is recommended as one means of ensuring that the equipment will perform its intended functions satisfactorily under all conditions normally encountered in routine aeronautical operations.

As previously stated, the aircraft equipage taking the lead in this marketplace is ADS-B due to its broad based reporting of situational awareness data. With ADS-B, pilots, like their controllers counterparts, will see radar-like displays, on existing electronic flight instruments, with highly accurate traffic data from satellites. This data updates and displays traffic situational information in real time and don't degrade with distance or terrain. The system will also give pilots access to weather services, terrain maps and flight information services. The improved situational awareness means that pilots will be able to fly at safe distances from one another with less assistance from air traffic controllers.

The gains in safety, capacity, and efficiency as a result of moving to a satellite-based system will enable the FAA to meet the tremendous growth in air traffic predicted in coming decades. Because ADS-B is a flexible and expandable platform, it can change and grow with the evolving aviation system.

ADS-B Benefits
  • Provides air-to-air surveillance capability.
  • Provides surveillance to remote or inhospitable areas that do not currently have coverage with radar.
  • Provides real-time traffic and aeronautical information in the cockpit.
  • Allows for reduced separation and greater predictability in departure and arrival times.
    Supports common separation standards, both horizontal and vertical, for all classes of airspace.
  • Improves ability of airlines to manage traffic and aircraft fleets.
  • Improves ability of air traffic controllers to plan arrivals and departures far in advance.
  • Reduces the cost of the infrastructure needed to operate the National Airspace System.

The United States FAA has issued an NPRM concerning the Avionics Equipage and is already deploying ADS-B field installations. The final rule and initial operating capabilities are planned for completion in Q2FY10. This leaves approximately 18 months from the date of this posting for aircraft owners and operators to evaluate potential solutions suitable for their aircraft and fleets.ASIG is currently supporting numerous ADS-B projects for a variety of aircraft and operators.

Until next time stay 5x5, Mission Ready & Wired!

To learn more about ASIG's approach to aircraft modernization programs or the products and services available from the Avionics & Systems Integration Group, please visit us online at, via email at, or contact us direct at 866.890.ASIG [2744].