New Angles on AOA
Would the widespread adoption of angle of attack instruments improve safety?
By Robert Goyer / Published: Feb 12, 2013
At the General Aviation Manufacturers Association's annual press briefing in Washington, D.C., on Tuesday, GAMA president and former military aviator Pete Bunce gave an impassioned argument about the necessity for the FAA to simplify its certification standards, a program the FAA is actually deeply involved in, with GAMA as one of its prime supporters. To illustrate the need for the change, Bunce used the example of angle of attack (AOA) indicators, which are available both on the Experimental market and as certificated products. The units intended for homebuilts, Bunce said, can be had for less than a thousand dollars. Those that go through FAA certification, on the other hand, go for around ten times that price.
New GAMA chairman Brad Mottier, who is in charge of general aviation efforts at G.E., seconded Bunce's endorsement of AOA indicators, pointing out that he (Mottier) had written his master's thesis on the subject of AOAs for light GA as an engineering student back in the late 1970s.
There was really nothing to disagree with in what Mottier and Bunce were saying during the presentation. Who wouldn't want instruments such as AOA indicators to be priced reasonably for the light GA market. After all, a tenfold price delta between the uncertified and certified products must indicate that the cost of certification is at least largely to blame for the higher cost of the FAA-approved gear.
But another question lays unaddressed: Would AOA indicators, if installed in every airplane in the fleet, dramatically improve the accident picture?
At an informal gathering the night before the event, Mottier had pointed out that nearly half of GA accidents are a result of loss of control. Therefore, AOA indicators, which constantly monitor the airplane's angle of attack (without exceeding the critical angle of attack, the airplane is not going to stall), should eliminate many loss of control accidents. After all, most business jets are equipped with AOA alerting systems and their safety record is sterling compared with light GA. AOA indicators must be the reason, or at least a big part of it, right?
I don't know.
I'm all for AOA awareness, but remember, we all have the ability to monitor our own AOA on a continual basis. Except in a few fairly high-risk cases, if you fly within the envelope, you're going to be well within the AOA limits to begin with. There are exceptions of which we should be well aware. The base-to-final turn is a case in point. You're low, you're slow, you're banking and you're dirty. In any such instance, your own internal AOA alert system should be flashing in and out of the red. What do you do? Unload the nose and keep the ball centered. It's hard to stall when you're keeping the airplane happy. In this case, is an AOA indicator a help? Absolutely. Would I like one? Sure.
But don't confuse increased awareness with any active mode of help. What an AOA indicator won't do is push the stick forward.
I think a more realistic approach, especially given the often marginal proficiency of pilots who don't or can't fly as much as they'd like to, is envelope protection, like that afforded by Avidyne with its aftermarket DFC90 autopilot and Garmin with its ESP product in the Cirrus lineup of light airplanes, the re-emerging Cessna TTx and others, as well as a number of slightly more expensive business aircraft, like the awe inspiring Bombardier Global 6000.
With envelope protection, an always-active autopilot working in the background monitors AOA, airspeed, and aircraft configuration, among other factors, and will actually maneuver the airplane to keep it within the envelope and generally out of harm's way.
After all, loss of control is often associated with distraction. What good does an indicator do if the pilot is too distracted to notice it?
And with autopilot prices affected by the very same factors as Bunce discussed in reference to AOA indicator certification, lower cost envelope protection in the form of sophisticated autopilots is every bit as much within our reach as high-quality AOA indicators are.