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ADS-B by 2020?

ADS-B by 2020?

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Illustration by John Macneil

It shouldn't be much of a surprise that there may be an equipment mandate on the horizon for general aviation aircraft owners. The FAA's associate administrator for Aviation Safety, Nicholas Sabatini (a GA pilot himself), reconfirmed it in a speech last week, saying that the agency was "working on a notice of proposed rulemaking that will propose to require ADS-B [automatic dependent surveillance-broadcast] equipage by 2020 to assure access to certain airspace."

"There are still issues to be resolved before a mandate can be justified," said AOPA President Phil Boyer. "But if that deadline holds, it would be 40 years from the last equipment mandate - Mode C transponders for operations within 30 miles of Class B airports.

"And ADS-B brings so many benefits to GA pilots that AOPA has been a long-term supporter of the technology."

Foremost on the GA pilot's mind is cost. Today a universal access transceiver (UAT) - the linchpin of ADS-B technology - costs about $8,000 installed. To get all of the benefits of ADS-B - graphical and textual weather displays (FIS-B) and traffic alerting (TIS-B) - you also need a multifunction display. That adds another $3,000 or more to the cost.

"The cost of a UAT should drop significantly once they're manufactured in quantity," said Randy Kenagy, AOPA director of advanced technology. "But the cost doesn't become affordable, in our view, until it equals that of a transponder."

Nor is it reasonable to mandate ADS-B for GA until collision-avoidance technology is developed that would allow GA pilots to remove the transponder or replace it with ADS-B.

The FAA isn't there yet, because it hasn't designated a replacement for TCAS - the traffic alert and collision avoidance system mandated for all airliners. TCAS requires altitude-encoding transponders on all aircraft to provide collision alerts in airliner cockpits. That's why you have to have a Mode C transponder whenever you fly in or near Class B airspace.

"If we have to add a box, we should be able to get rid of an obsolete box," said Kenagy.

Finally, there is the issue of redundancy. ADS-B technology relies on GPS for both navigation and surveillance. If accurate GPS position information becomes unavailable, pilots lose navigation capability, and air traffic controllers lose sight of traffic.

"The FAA can't achieve its goals of a new, high-capacity ATC system if it leaves pilots without navigation information or controllers relying on a skeletal network of radar systems. The FAA needs to resolve what it will do to ensure it has technology in place that provides position information 100 percent of the time before mandating ADS-B," said Kenagy.

But clearly the FAA is moving toward an ADS-B future. The agency is expected to issue a contract later this year for a private vendor to build and operate the ADS-B ground infrastructure. And the Capstone office in Alaska has now been integrated into the national ADS-B office. Capstone was one of the proving grounds for ADS-B.

January 18, 2007

Topics: ADS-B

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