Better With ADS-B The Proof is In

--by John Croft, FAA Office of Communications

It’s no accident that Jimmy Wright is an emissary on the virtues of Automatic Dependent Surveillance – Broadcast (ADS-B). In fact, it was an accident that made him such.

A wrong turn in a blinding snowstorm near Sitka, Alaska in December 1994 resulted in his Cessna 206 floatplane crashing on a beach and hurtling into a wall of spruce trees. Despite immense odds, he lived to tell the tale. For the past 15 years he has worked tirelessly as an FAA contractor to get general aviation pilots to equip with ADS-B and the moving maps on which they typically display the uplinked traffic and weather.

Jimmy Wright (left) and friend, Kerry Wade, prepare for a trip in Wright's DeHavilland DHC-2 Beaver floatplane.

For Wright, ADS-B avionics and a moving map — brought to Alaska with the Capstone programs that started five years after his crash — would have made all the difference in the world.

The Report Is In

A new safety analysis and reports from the field show that the efforts of Wright and others have been worth it. ADS-B is making a positive difference for safety, and not just because of traffic and weather.

A growing number of indirect or complementary benefits are emerging, not the least of which is an evolution in the safety culture in the cockpit and in flight following. Using ADS-B In, pilots who now have traffic and weather at their fingertips are determining their own best practices for strategically avoiding what could otherwise be a narrow escape with another aircraft, or a rain shower or thunderstorm. Dispatchers, with the benefit of highly accurate one-second position updates, are able to track the location of all of their assets precisely.

The safety analysis, funded by the FAA, focused on general aviation (GA) and small air taxi accidents in the continental U.S. and small air taxi accidents in Alaska between 2013 and 2018. The results show a significant reduction in the accident and fatal accident rates for aircraft equipped with ADS-B Out and In compared with those that were not equipped, in part due to the cockpit displays that pilots typically add when installing the avionics. ADS-B In provides air-to-air and ground-to-air (from FAA radar) traffic and through the 978 MHz UAT link, a variety of weather products, including local and regional NEXRAD and weather at airports.

The authors of the report, FAA contractors Daniel Howell and Jennifer King, found that GA and small air taxi operators who installed ADS-B Out and ADS-B In, including a panel mounted or portable display with moving map and terrain clearance applications, experienced a marked decrease in three types of accidents: weather-related, controlled flight into terrain (CFIT), and CFIT combined with weather. Howell and King noted that there was a “measurable” reduction in midair collisions, but since such accidents happen so rarely, there was not enough data to prove a “statistically significant” reduction as they had proven with the other accident types.

Howell and King split their accident research into two groups — those in Alaska, which has had the ADS-B infrastructure since 2005, and those in the lower 48 states, where the infrastructure was mostly complete in 2013. For Alaska, they studied air taxi accidents from 2005 – 2017, identifying ADS-B In equipped accident aircraft by comparing tracking data from the FAA’s ADS-B Performance Monitor with NTSB accident data. The monitor, which receives ADS-B data from the FAA’s nationwide network, assesses the performance of individual aircraft compared to the requirements in the ADS-B rule.

For accidents after 2012, they determined which aircraft were equipped with ADS-B In through a bit in the ADS-B Out stream that indicates the aircraft is equipped with ADS-B In. For accidents before 2012, they used FAA Capstone records to determine which aircraft were equipped.

Key to coming up with accident rates was determining how often the aircraft flew and which ones were equipped. The study considered both FAA data on arrivals and departures, information from the Bureau of Transportation Statistics, and FAA information on fleet equipage.

Howell and King concluded that Alaska air taxis with ADS-B In experienced an overall accident rate that was 55-percent less than those unequipped. That translates to approximately 90 accidents avoided between 2005 and 2017. The estimated drop in the accident rate is more than twice the FAA’s initial estimate that ADS-B would result in a 20-percent reduction in accident rates for Alaska. They also found no “statistically significant” reduction in the fatal accidents for Alaska as the numbers were similar for equipped or non-equipped aircraft.

For the continental U.S., the average rate reduction across four types of accidents (mid-air, CFIT, weather-related, and CFIT plus weather accidents) was approximately 50-percent for equipped aircraft, with a cut in the fatal accident rate of about 90-percent. That translates to about 36 fewer accidents and 16 fewer fatal accidents between 2013 and 2017. As additional aircraft are equipped and more time goes by, the FAA will be able to get a more precise handle on the direct safety benefits of the technology. After January 1, 2020, all aircraft flying in “rule” airspace will be required to carry ADS-B Out.

Jimmy Wright (left) prepares to load the DHC-2 Beaver with cargo prior to launching on another flight in Alaska.

More than Traffic and Weather

What is not obvious in the study results are the secondary benefits that operators, pilots, investigators and others are increasingly discovering.

One area where ADS-B Out is boosting safety and situational awareness is with flight following — a capability that would likely have sped up the rescue operation for Wright. On that fateful day, Wright was flying from Juneau to False Island to Angoon then back to Juneau. The standard operating procedure at the time was to have a flight plan for each leg and for the pilot to call the home base every 30 minutes en route on an FM radio frequency, along with calling after a takeoff or landing. Dispatchers would keep track of the reported positions on a spreadsheet. In some cases, radio contact wasn’t possible and calls couldn’t be made on time because of the terrain.

It was on the leg from False Island to Angoon that Wright encountered the snowstorm. Based on his flight plan and departure call, the air taxi’s agent in Angoon knew when his flight should have arrived. Ten minutes after his ETA, the agent knew something was wrong. What he didn’t know was where, along the 25 nautical mile route, Wright had disappeared. The search began, but finding him took much longer due to the lack of surveillance and the limited reception of his 121.5 MHz Emergency Locator Transmitter in mountainous terrain.

That’s a situation air taxis in Alaska no longer have thanks to ADS-B Out. “We have in our flight follower’s office and in our main office a program that has a map showing all of our equipment — tail number, position, altitude, and speed, based on standard pressure,” says Brett Coblenz, chief pilot of Juneau-based Alaska Seaplane Service. Coblenz says there are still some “dead zones” where the ADS-B Out signal can’t be received, “but for the most part we can see where the aircraft are at all times on a computer screen.” When they do receive ADS-B, they can narrow down an aircraft’s position to about 1,000 ft.

ADS-B position accuracy and a speedier recovery could have made a difference for Wright, who ultimately lost part of his leg in the accident. After his recovery, Wright returned to floatplane flying until he joined the FAA as a subject matter expert on ADS-B in 2004, based largely on his experience with Capstone. Today, he is a human encyclopedia of knowledge about the technology, and rarely is he not on the phone talking to repair shops, manufacturers, and pilots solving technical problems. He is also a regular staffer of the ADS-B exhibit at various trade shows throughout the year.

“I’m always on the lookout for ways to serve,” he says.

Jimmy Wright is a familiar face at the FAA booth at Sun 'n Fun and other shows, where he helps pilots assess their ADS-B performance.

John Croft is a flight instructor and a speechwriter/editor in the FAA Office of Communications. Croft uses ADS-B in the Piper Archer he co-owns with two other pilots, and he regularly flies a small team of FAA communicators to talk to pilots and other stakeholders about ADS-B.

This article was originally published in the July/August 2019 issue of FAA Safety Briefing magazine.
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