By JOHN CROFT, FAA
LYNCHBURG, Virginia — Intuition says that ADS-B In can help reduce the risk of a collision, but can an economic case be made to equip?
Andrew Walton, director of safety for Liberty University’s School of Aeronautics, came up with a cost-benefit analysis that proved it can, and he used it to convince his employer to support the purchase of ADS-B In for a fleet of 25 aircraft.
The extra cost was significant — $5,000 over the purchase and installation costs of the ADS-B Out system for each of the school’s Cessna 172s and twin-engine Piper Seminoles.
Walton analyzed several ADS-B In offerings, some that were lower cost, but favored sticking with their original avionics provider.
“We wanted a solution that would show the traffic on the multi-function display,” he says. “That way we didn’t have to install another box and the ADS-B In information would be seamless for our instructors and students.”
Money was not initially a factor in Walton’s thinking. In 2012, he systematically surveyed the risks for the university’s flight training operation as part of a Safety Management System evaluation, studying more than a decade of flight training accident statistics from National Transportation Safety Board (NTSB) records. He determined that the highest fatality risk for flight training operations was loss of control (LOC), followed by mid-air collisions.
To address LOC, the university retooled its stall training and invested in angle-of-attack sensors for all of its aircraft.
Liberty has 50 flight instructors training about 200 students in any given semester. Its aircraft typically fly 50 times a day, accumulating about 14,000 training hours a year.
Walton’s economic analysis used NTSB crash data, along with FAA estimates of flight training hours nationwide, to determine a fatal mid-air risk per flight hour. He estimated that eight of the 24 fatal mid-airs that occurred during the study period could have been prevented with ADS-B In.
Based on U.S. Department of Transportation (DOT) methodologies, the cost savings in averting those eight crashes — that would have killed approximately 14.4 instructors and students — boiled down to just under $4 per flight hour. Since each of Liberty’s aircraft fly approximately 600 hours a year, the break-even point for justifying the added cost of ADS-B In would be reached in just under three years per aircraft.the break-even point for justifying the added cost of ADS-B In would be reached in just under three years per aircraft.
The university determined that the investment was sound and allocated money to buy the ADS-B In equipment along with ADS-B Out. His team started adding the feature in spring 2016 and took about a year to install it in all aircraft.
“We could have installed just ADS-B Out for less cost, but we reasoned that the safety benefits of a system that would tell you ‘Traffic! Two O’clock. Two Miles. Same Altitude,’ would more than justify the cost,” says Walton. “If it avoids one mid-air collision, you’ve paid for it, easily.”
The flight school previously had used the Traffic Information Service (TIS) available with its installed avionics, but Walton says the TIS traffic callouts were based on local radar and did not make audio announcements of the traffic’s location, distance, and altitude. He says there were also dead zones in the radar coverage, a shortcoming largely eliminated with ADS-B.
Evidence of ADS-B benefits at the flight school is mounting, says Walton.
“We have had various safety reports of traffic conflicts where instructors or students have said, ‘Because we had ADS-B, we were able to see the traffic coming and take evasive action that had we not taken, would have led to a close call,’” he says.