Hats off to the FAA for finally suggesting that all airplanes be equipped with angle of attack systems. The agency recently published a special airworthiness information bulletin (SAIB) recommending that AoA systems become standard equipment in new airplanes and retrofitted in existing ones.
As background in the bulletin, the FAA calls attention to the 2009 Colgan Air Dash 8 airliner crash in New York, and the flying pilot’s “inappropriate response to the airplane’s stick shaker” and the resulting low speed and eventual stall. But you don’t have to look far beyond the highly publicized Colgan wreck to find plenty of other ones where the pilot simply didn’t recognize a slow-speed condition by referencing the standard airspeed indicator alone. Never flown with an AoA? I hadn’t, either, until I had a crack at Safe Flight Instrument Corporation’s wing leading-edge speed indexer in the company’s Beech Baron in the mid-2000s. I’ve been a believer ever since. Since Safe Flight invented the stall warning system lift detection system in the 1940s, its AoA tech leverages a similar wing leading-edge sensor for AoA and speed indexing. That’s a photo I captured of Safe Flight’s second-gen system from a demo flight on approach to Waterbury Oxford Airport in Connecticut in the company’s Cessna.
The theory in which Safe Flight’s system measures AoA boils down to the very basic fundamentals of wing lift. Plus, I think a leading-edge lift transducer is one of the most accurate ways of measuring AoA because the system is accurate regardless of aircraft weight, wing loading, turbulence or wing flap configuration. As the aircraft wing moves through the air it divides the air mass. At the center of this divided airflow is a narrow region known as the stagnation point. The location of the stagnation point uniquely represents the wing’s AoA. The system’s lift transducer—installed on the leading edge of the wing—senses the location of the stagnation point by means of a spring-loaded vane. The sensor isn’t a replacement for the aircraft’s stall warning system but is installed in the opposite wing. For an OEM standard, I think the system can work well. The system I flew with used an indexer mounted on the glareshield as you see in the photo, but it’s easy to interface with a primary flight display in both new and retrofit avionics.
Of course, AoA systems have been standard in higher-end avionics for a while now but there are plenty of federated panels that can benefit from aftermarket systems, and while there have been lots of retrofits—and integrated AoA features in Aspen Evolution flight displays and others—I think there can be lots of prevented wrecks with more installations. And now with the FAA advocating AoA equipage for all aircraft, why not sweeten the deal much like it did during the ADS-B Out equipage mandate rush? At the time, the FAA was handing out rebates for qualified installations and it was successful. And now that we have an approved high-octane unleaded avgas that’s being distributed and pumped, perhaps the FAA can focus its efforts and dollars to equip the fleet with AoA systems, while also working on a training initiative so pilots can use them safely. We’ll look at available system options in an upcoming issue of Aviation Consumer.
This story originally appeared in Aviation Consumer Magazine in January 2025
I like it. I agree. What’s not to like? This instrument will save lives if people learn to use it regularly and smartly. Good catch, bring it on!
An AoA would not have prevented the 2009 Colgan Air Dash 8 airliner crash in New York. The route cause of this accident was do to poor training and checking by training department.
Completely agree that for light GA, AOA is just another distractor.
Real AOA value is in aircraft with a substantial weight change during flight (fuel burn and/or expendables…e.g. ordnance, airdropped cargo, etc) that changes critical airspeeds substantially, tactical ops at corner airspeeds (upper left limit of envelope, or irreversible hydraulic systems and/or airframe characteristics that provide no airframe aero or control feedback.
In light GA we have the luxury of minimal weight change during flight, talkative control force feedback and no combat need to operate at upper left corner of envelope (but it is a fun area to operate with correct trng/acft). Training and proficiency allow you to unlock GA acft feedback cues so that the entire acft becomes an AOA indicator IF you learn to feel what the airframe/controls are telling you…and they are tactile which is a powerful feedback loop (wonder why stickshakers are used?)
Some practical considerations for AOA in GA…no redundancy (Air France and 737 Max type false input issue), recalibration/damage inspection before each flt, trng to use AOA and understand limits…$$ spent that could have been used for proficiency flying. The overwhelmed, less proficient GA pilot who can’t interpret airframe/control feedback is going to have just another input they can’t interpret in extremis…see article on recent Canadian mishap for similar issue.
AOA refs are not going to correspond to actual performance of an iced up airframe.
Opinion above based on years of USN TACAIR experience with AOA, and non-AOA in aerobatic GA.
As far as $$ from heaven (or FAA), I’ll settle for a waiver on ELT install with “ADS-B out” installed on flight within ADS-B coverage areas.
Basically good but what’s not to like is the spring loaded vane. Think icing or mechanical failure. But, maybe I’m missing something.
Share concerns…as far as icing affecting vane, if you have ice on vane then any AOA ref is useless, iced airframe will stall at different AOA than non-iced reference values…you now have a different wing profile.
An essential IFF.
Clarity is needed in flight decks.
AOA vanes on aircraft like B737 are heated.
(Heat does have to be turned on.)
Icing awareness is essential - did an ATR fall down in Brazil a year or three ago when pilots did not appreciate how bad icing was and behaviour of the specific type of airplane?
The problem in GA is not a failure to spend large $$ on flight deck equipage, it’s a failure to know how to operate the acft when the going gets tough. There is no shortage of smoking holes that were, up until that point, perfectly good, well equipped acft flown by non-proficient PICs.
AOA for a non-proficient pilot is like $300 Nikes for a donut run.
Heated AOA will report AOA as calibrated, but issue lost on most not well versed in AOA is that an iced airframe is one time that stalling AOA will vary from ref…and we’ve all seen what a little frost can do.
I agree with Edwisch and Rich R. In the two jets I am typed in both have an AoA indicator that is used for reference. Determining proper approach speeds are still used as primary indication for approach speed at the approach weights. As far as I know the manufacturers of small jets haven’t changed this. I fail to see how in an airplane that might weight 2300lb at gross when the fuel load probably doesn’t exceed 240lb. Not much change in weight for such a plane. Now the jet I fly now holds 10000lb of fuel, making the change in weight after fuel burn much more dramatic. Also icing will reduce the angle of attack of an airfoil making the AoA gauge inaccurate unless it is designed to compensate for icing, something most light airplanes aren’t even certified or equipped for.
I have flown with AoA in jets, large and small, and I like it, but the average GA pilot will not gain anything from it. Anyone who can not interpret slack controls or a buffeting airframe has no business in the left seat and another doohickey won’t help.
I’m sadly reminded of the recent B-787 crash that apparently took off with zero flaps deployed and sunk nose high into the ground. That’s simply poor airmanship/training.
This doohickey will probably save a number of folks who get saturated with the stick and rudder stuff when on takeoff or approach. It won’t do much for the “Ace of the Base” until things really go sideways. For the rest it may mean the difference of going home for dinner or being fondly remembered days later.
Retail therapy is not the answer, training and proficiency are. For those who are not $$ limited, knock yourself out and add another doohickey you can show off as part of your $50k glass panel in your 172 you fly once a month.
For those who are time limited, I’ll let you in on a secret, if you are not proficient in stick/rudder, then you probably won’t be in AOA ops either, AOA helps in steady state approach to onspeed. When you’re fighting snakes in the cockpit, large control inputs will blow past AOA utility, it won’t be in your scan and any warning will be as the stall break occurs, lost in the sensory overload.
Go spend your $$ on training and gas, if you don’t have time for that, buy a simulator and sell the acft, that too will save lives.
A condescending response regarding the G.A. Community who don’t get paid to fly jets. Training is worthwhile and so are technologies that help save lives. I’d be thrilled to have a 172 with a $50,000 glass panel but I think many don’t enjoy that luxury. If government agencies have seen the value in AOA technology and can assist grassroots owners with equipping their machines with something that may save the day while being somewhat affordable I’m for it. One day it just might appeal to others as well.
Yes, condescending to the attitude that tech is the solution, with no first hand experience of the tech, its limitations and required training/proficiency to effectively employ.
No condescension to any GA pilot who learns their acft/operating regime and makes the effort to stay proficient, regardless of their acft, whether that be ultralight, 172 or jet. I am tired of seeing idiots kill their family and friends because their ego exceeded their skill.
The Q400 in that crash did have an AOA indicator in the form of a low speed cue on the airspeed indicator, a prominent stick shaker, and a stout stick pusher. As a former Q400 pilot myself, I believe an additional AOA display wouldn’t have changed that accident. AOA systems in small GA aircraft are valuable, but won’t change poor piloting responses without good, consistent training.
Yes, because it’s the public sector’s financial responsibility to equip private aircraft with additional systems… Should the DOT pay to equip my old pickup with a backup camera and collision avoidance systems and training on their usage? Or should I just pay more attention as a driver? Safety systems are only as valuable as the end user, and that same user should be responsible for equipping themself and their aircraft.
Chuck Yeager:”If you need an AOA gauge to know your AOA, you probably shouldn’t be flying.”
Just another cockpit distraction.