AEA Pilot's Guide 2020-2021 - 71

who installed ADS-B Out and ADS-B In, including a panelmounted 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, 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 to 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 ADSB 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% 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% 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 (midair, CFIT, weather-related, and
CFIT plus weather accidents) was approximately 50% for
equipped aircraft, with a cut in the fatal accident rate of about
90%. 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. As of Jan. 1, 2020, all aircraft flying in "rule"
airspace have been required to carry ADS-B Out.

- 71 -

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," said Brett Coblenz, chief pilot of Juneau-based Alaska
Seaplane Service. Coblenz said 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 feet.
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 said. q
This article was first published in the July/August 2019 issue
of FAA Safety Briefing magazine. The author, John Croft, is a
flight instructor and a speechwriter/editor in the FAA Office of
Communications.

AEA Pilot's Guide 2020-2021

Table of Contents for the Digital Edition of AEA Pilot's Guide 2020-2021