Imagine one day in the near future looking at a multifunction display (MFD) in your cockpit and seeing virtually the same traffic information as air traffic control. Oh, and by the way, your MFD also shows you the latest weather, both text and graphics. That is the promise that ADS-B—automatic dependent surveillance-broadcast—holds for general aviation, and it is one very large step closer to reality now that the FAA has decided what systems will be used for "linking" the information to aircraft.
"AOPA has been a strong advocate for ADS-B and actively involved in testing the system through Project Capstone in Alaska," said Randy Kenagy, AOPA's director of advanced technology. "While it may not be right for every pilot, we are excited about the promise this system, and others like it being offered by non-governmental providers, holds for pilots to get weather, traffic, TFRs, and situational awareness information in the cockpit."
The architecture announced by the FAA calls for a higher end system for air carriers and high-altitude general aviation using a Mode S extended squitter, and a lower cost but highly capable system for the typical GA user, using a universal access transceiver (UAT), which functions much like the Internet connection in your home or office.
ADS-B-equipped aircraft digitally broadcast their positions derived from the on-board GPS receivers to other ADS-B-equipped aircraft and to ground stations. The information includes position, altitude, airspeed, and projected track, which can then be displayed on an aircraft's MFD or an air traffic controller's screen. As Project Capstone has proven, ADS-B can greatly extend ATC's "view" by using remote ground receivers where radar would be impractical and feeding the remote signals to the controller's screen.
In the air, the digital data receiver on an ADS-B-equipped aircraft opens up tremendous possibilities. An airborne ADS-B receiver will only be able to display signals from other ADS-B-equipped aircraft. But using traffic information system-broadcast (TIS-B), ATC will be able to uplink surveillance and en route radar data to the aircraft. In addition, a flight information system-broadcast (FIS-B) will be able to uplink both textual and graphical weather information for display on the cockpit MFD.
The FAA expects to have pockets of the ground infrastructure in place within the next four years, and that ADS-B will be in widespread use among air carriers within a decade. Currently, there are no plans to make ADS-B equipment mandatory for GA aircraft.
"There is no need to require it," said Kenagy. "As several existing providers of these types of service are proving, this type of system can be so useful it may become the 'must have' box on GA pilots' wish lists."