This Little Device Could Save Pilots’ Lives

Aviation safety experts say that “Angle of Attack” indicators in small airplanes could help prevent accidents.

AOA indicators use a variety of symbols to warn pilots. In this one, red means the angle of attack is too high.

Safety experts from the government, alphabet groups and the private sector gathered last week in Washington, D.C. for a daylong forum on how to reduce accidents due to aircraft “loss of control” in flight. The National Transportation Safety Board (NTSB), who sponsored the forum, says that LOC accounts for 46 percent of all fatal general aviation crashes.

The Federal Aviation Administration and others have been promoting Angle of Attack (AOA) indicators—cockpit gauges that give visual cues about the airplane’s position and help warn the pilot of possible stall conditions —as a way to prevent such accidents, and workshop participants discussed products that already are available, as well as safety research results and training challenges involved in using the devices. Wendell Griffin, Director of Accident Investigation and Prevention at the FAA, called AOA indicators “the biggest win for us so far” in helping to prevent LOC accidents.

Sean Elliott, Vice President for Advocacy and Safety at the Experimental Aircraft Association, said that while regulations have been streamlined to encourage use of AOA indicators, even basic systems are currently in the $2,000 range. “I think the cost/benefit is still out of whack,” he said. “If you could make the price tag in the hundreds of dollars and not in the thousands, you would see wide adoption.” Elliott said that NAFI has asked members to pledge to study AOAs and consider equipping their aircraft.

Dennis Beringer, a research engineering psychologist with the FAA’s Human Factors Research Division, discussed how different AOA indicators present data to pilots. Comparing a selection of displays from current and proposed systems, he noted their disparity in symbology, and said, “We need to put into place display standards for these things to make sure they are effective across the board.”

Thomas Turner of the American Bonanza Society pointed out that current aftermarket AOA systems require pilot calibration, a process that involves precise flying that may be beyond the skills of some, resulting in indicators that are improperly calibrated.

The NTSB recently added a checkbox on its accident report forms to indicate whether aircraft were equipped with an AOA system at the time of an accident, but, according to Board member Earl Weener, “we have not had enough accidents [since adding the checkbox] to draw any conclusions.”

Meanwhile, the University of North Dakota has been sifting through data from its flight data monitoring program, which gathers detailed information on the 115,000 annual flights of the university’s fleet of 120 aircraft. Associate professor Jim Higgins told workshop attendees of one intriguing finding: On the base-to-final turn, the aircraft nose would typically drop about 0.7 degrees more on airplanes equipped with AOA indicators than on those without. “One interpretation would be that pilots are responding to the angle of attack awareness and lowering the nose when turning final,” Higgins said.

Regardless of equipment on board, Jonathan Sackier, a surgeon representing AOPA, said that 12 percent of fatal accidents are caused by a medical condition, and urged pilots to do a better job of evaluating their fitness to fly before every flight. Sackier led off his presentation with a personal anecdote that brought home the urgency of the workshop topic, noting the death of a colleague and his young daughter in a crash just days before. “If something eminently preventable led to the death of my friend and his daughter, how obscene is that?,” he said. “His memorial service starts in 30 minutes. I chose to continue my commitment to be here in his honor.”

Margins of Safety: Angle of Attack Indicators

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