Hop on the bandwagon–Angle of Attack (AoA) is the new must-have aviation accessory.
This year’s Oshkosh fly-in was just the latest evidence, with a number of new product introductions, safety seminars and ad campaigns all proclaiming the life-saving potential of AoA instruments. Since loss of control is still the number one cause of general aviation accidents, the AoA revolution could be the most important safety innovation in our lifetime, we heard.
I think that’s hopelessly naive.
Given all the hype, a casual observer might think the concept was just discovered. But as any pilot with even a basic knowledge of history knows, it’s been a hot topic numerous times over the years, as far back as Wolfgang Langewiesche’s classic book Stick and Rudder. Today, almost every turbine airplane has an AoA instrument. It’s hardly a new idea.
The latest push has centered on bringing this technology to piston airplanes. It started with the FAA, who declared affordable AoA instruments one of its most-wanted safety improvements. AOPA’s Air Safety Institute has enthusiastically supported the cause, too.
But the most newsworthy AoA story to come out recently was courtesy of ICON Aircraft, the designer of the yet-to-be-delivered amphibian LSA. They recently released a video touting the AoA instrument that will be front and center in their A5 cockpit. The glitzy video presents AoA as if it’s a major breakthrough in aviation and ICON is the first airplane ever to offer it.
I don’t blame ICON. This is the type of thing startups have to do to get attention and keep customers excited during the long march from concept to shipping a product. And their AoA design does look appealingly simple. But the media who accept this at face value and the “safety experts” who think it’s a revolution should know better. AoA is an instrument, nothing more, nothing less.
Some AoA advocates point to the Asiana 214 crash in San Francisco as an example of the type of accident that could be prevented with such an instrument. To me, it shows exactly why AoA won’t do much. Most importantly, the pilots have to look at the instrument for it to be of any use. In the Asiana case, the crew managed to ignore the airspeed indicator for a long time, even as it eventually showed them being almost 30 knots slow. Another instrument wouldn’t have prevented this disaster.
Besides looking at the instrument, pilots have to know how to react to its indications. For the GA pilot struggling to log 25 hours in a year, the physical stick and rudder skills may be more important than the recognition skills.
An AoA instrument also won’t help the idiot who buzzes his girlfriend’s house at 20 ft and pulls up at 3 Gs. Neither will it prevent the over-gross takeoff on a hot day that eventually results in a stall. These scenarios are both depressingly common, and get grouped under the “loss of control” heading.
Ex-military pilots (like some on the ICON team) love AoA because it’s religion in the military. To them, it seems shocking that GA pilots are still flying based solely on airspeed. I’ll admit that, when landing on the pitching deck of an aircraft carrier at night, AoA is probably a great tool. But for the average Cherokee pilot landing on a 5000 ft. runway, the situation is quite different.
Here’s the simple fact that most AoA proponents know, but don’t like to admit: airspeed is a great proxy for AoA most of the time. General aviation pilots fly in a very small envelope: +/- 10 degrees in pitch and 30 degrees of bank in most cases. Within those boundaries, monitoring airspeed is a perfectly good way to keep from stalling. If you’re doing aerobatics or flying a jet at FL410, an AoA instrument may be essential; in the pattern in a 172 it’s not going to tell you much more than the airspeed indicator.
Yes, I know that “a wing can stall at any airspeed,” but how often do you read about a stall/spin accident that occurred at 150 knots? Most of the base-to-final stall/spin scenarios happen because the pilot got too slow, plain and simple. That suggests good airspeed control would improve safety more than a new instrument in the cockpit.
But here’s where the breakdown is. Ask most flight instructors and they’ll tell you that new students and licensed pilots alike are dreadful at airspeed control. If the common standard of staying within +5 and -0 knots of Vref were enforced, thousands of pilots would have to surrender their certificates.
We don’t have an instrument problem, we have a stick and rudder skills problem. Instead of spending a lot of money on new instruments, let’s teach pilots how to maintain the proper airspeed on final. That would be revolutionary.
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Good article. I agree completely.
I agree completely too.
I agree completely three
Hey Mark, Thought that C-17 used AOA?
It seems this article is relevant to the recent crash of the Lionair Boeing 737 Max
Situational Awareness. Your assumption that AOA would not have helped the Asian crash or foolish pilots buzzing the girl friends house may or may not be valid, but having a device showing how the wing is performing in a given situation/configuration will improve the pilot’s awareness of the aircraft’s aerodynamic performance. AOA would do a much more effective job than a stall warning horn. Tim Brady, dean of Embry-Riddle’s college of aviation in Daytona Beach, said “We want to give (students) one more tool to help them recognize the performance limitations of the airplane,”.
The fact is, it doesn’t show the AOA…it shows an engineer’s interpretation of the AOA corrected for configuration, etc., and as Air France 447 shows, when engineers get in the way of the aerodynamics, things fail.
When things fail, it’s elementary stick and rudder skills that save the day–ask any of a countless number of test pilots who tested, designed, and flew countless airplanes in the early stages.
“…it shows an engineer’s interpretation of the AOA corrected for configuration, etc”. Nope, not buying this argument. All of those complex charts in the back of the POH are “engineer’s interpretations” and I relay heavily upon them for computing the airplane’s performance. Also, I don’t see this as an “either/or” kind of discussion. Certainly pilot stick and rudder skills should be stressed, I just think the AOA is a huge improvement over our current “interpretations” of in-flight aircraft performance.
Dave – I agree with you and disagree with the author. Sure, if pilots only followed the airspeed indicator and book speeds, AND kept the bank at 30 degrees or less in the pattern, AND kept the ball centered, AND kept aircraft weight at or below book gross, THEN they wouldn’t stall and spin in the pattern. That’s a lot of “ands” that obviously are not being followed by all pilots all the time – even highly experienced and capable professional pilots are losing control of their GA aircraft all too often.
An AOA indicator that provides constant indication of the actual angle of attack of the wing under the actual conditions of flight, placed in the pilot’s field of view (adjacent to the six-pack, or better yet, on a HUD) would over time help pilots develop a much higher level of AWARENESS of how well the wing is flying. Awareness of AOA won’t make airplanes idiotproof, but over time good awareness provides an opportunity for pilots to learn to develop the proper stick and rudder skills … because of the immediate feedback that the AOA indicator provides that cannot be seen from merely tracking airspeed.
Honestly, I don’t get the resistance to AOA from so many pilots, other than it’s a case of stubbornness and arrogance (“if only all pilots were as smart as me, these accidents wouldn’t happen”). It seems to be more reactionary than thoughtful. And there is also an unwillingness by too many anti-AOA people to recognize that the way we teach and maintain piloting skills obviously needs a great deal more improvement, because the accident stats don’t lie … the system IS broke, and IT NEEDS FIXING.
AOA indicators are not a panacea for GA safety – but then nobody is arguing that they are a panacea … yet this is the same old same old straw-man argument that the author of this piece and the other AOA resisters keep bringing up.
Direct AOA readouts in the cockpit are appropriate and necessary to teaching pilots how their airplanes actually fly, and how they stop flying. Teaching only airspeed control misses the boat on the pilot’s understanding of how to keep the clean side up, especially in low altitude pattern turns, high gross weights, and strong crosswind conditions, which collectively are the great killers of GA pilots.
Who can seriously argue that ignorance is bliss?
“if pilots only followed the airspeed indicator and book speeds, AND kept the bank at 30 degrees or less in the pattern, AND kept the ball centered, AND kept aircraft weight at or below book gross”
YES – that’s the PTS! You shouldn’t take off over gross, you should fly with the ball centered and you should be able to maintain Vref on final. That’s not advanced flying, that’s not pilots being arrogant – that’s basic airmanship that needs to be taught.
John – Yes, that is the PTS, it’s not “advanced flying”, and it is the secret to keeping the clean side up.
The problem is, too many pilots aren’t doing it correctly every flight, for whatever reasons. There is no “panacea” to this problem, but I do believe arrogance is involved when reasonable options to improve pilot understanding and performance are scoffed at because they’re (obviously) not “panaceas”.
For one thing, AOA indicators won’t tell the pilot how to work the rudder, and avoid the deadly skidding base to final turn. A skillful pilot knows how and when, and how much rudder to apply, and ought to be able to “feel” it thru the seat of his/her pants.
Yet we have turn coordinators on our panels with little balls in them that tell us graphically whether we’re coordinated or not, and what we need to do to correct a skid or an unintended slip. The good stick and rudder pilots don’t need the little ball most of the time, but the ball certainly helps to train (or re-train) pilots to recognize what it feels like when the ball is centered, or not centered. It’s immediate feedback.
I don’t hear commenters railing that we need to rid ourselves of the little ball in the TC because “they are not a panacea” to poor rudder control, or that “that just gives the pilot something else to not look at”.
I was a total IAS guy until I checked out in the Mac Doug F-4. At first the AOA was just another inst to x/check on final approach. Wrong!! I came to love it! No matter how shot-up and damaged, even loss of hyd/air for flaps; AOA at 17 units in the f-4 works…..you always know exactly where the stall point is!! I do agree, though. In a light plane it could actually be dangerous as a diversion to an already over loaded student or low time pilot. Nothing replaces IAS!!
It’s funny you should mention military pilots preaching the virtues of the AoA indicator. My co-pilot was just whining the other day that the KC-10 should have one, since virtually every other fixed wing military aircraft has one installed as required equipment. I said we had AoA vanes that sense an impending stall that actuate the stick shaker and annunciate alpha speed on the FMA’s, so what else did he need?? He didn’t like my answer and insisted it would be better if we had one. My thoughts are, to what end?? Are you really going to try to fly a DC-10 closer to its limits because you have an AoA indicator telling you that you haven’t crossed into the stall regime?? I’d much rather the safe, published bug speeds were flown, and not worry about “max performing” the aircraft. Especially when close to the ground!!
I wouldn’t need to check my load, figure a weight, and calculate bug speeds if I had AOA. Instead I’d know one number for the platform forever always.
And what would that number be? Most GA AoA units don’t display numbers.
I agree that stick-and-rudder skills are the most important safety enhancement needed in GA. Additionally, I also agree that the moron that buzzes his girlfriends house or tries to fly under power lines is not the type to even consider buying an AoA instrument. Nothing will help these people.
So, you have clearly stated the problem and suggested a solution. Do you have a suggestion on how we implement your solution?
I got my ticket in December of 2012 and as of today, I have 98 total hrs. AOA would have (during training and even now) benefited me in simply visualizing and better comprehending how much or how little margin there is. Not so that I can purposely max perform the airplane but so that I can better understand the relationship between the relative wind and the wing. During training it’s taught mostly from an academic perspective. Stalls are taught yes, but that always focuses on airspeed. Airspeed airspeed airspeed…but that has nothing to do with AOA. So are my stick and rudder skills after a mere 98hrs where they should be? Absolutely not. Am I continuing to advance those skills? Yes. But seeing how a maneuver actually affects AOA would be greatly beneficial and a whole lot safer than me testing my skills and crossing the line. My .02
Only safe pilots make safe airplanes.
Excellent article and feedback.
When the subject of useless gizmos comes up, I always have to wonder how the birds get by without them. Nothing replaces skill and feel for performance whether it’s flying or playing a guitar.
I agree on many points and would like to add one:
AoA doesn’t always work in unusual attitudes. If you gradually pitch up 90 degrees and hold the airplane vertical (an extreme but simple example) then the AoA will quickly return to a normal value. Airspeed, however, will fall rapidly. In this scenario, neither an AoA gauge nor a stall horn will indicate loss of lift.
Better visualization of the concept of relative wind is simply less important than flying the airplane by reference to the primary flight instruments. That concept should be fully understood on the ground before walking out to the airplane, and here’s why: an AoA indicator just tells you what angle the relative wind is hitting the wing. Thats it. It doesn’t tell you if you’re in a climb or descent. It doesn’t tell you if your airspeed is decreasing. It doesn’t tell you what altitude you’re at. It doesn’t tell you if your turn is coordinated. It doesn’t tell you if you’re stall speed has increased because you’ve loaded the airpane with more than 1G. Losing track of those factors is what contributes to pilot’s getting into a stall/spin accidents in the first place. The main point the article makes is installing an AoA indicator isn’t a panacea to GA stall/spin accidents in the low altitude environment, which is what the safety folks are trying to use as a selling point for buying AoA indicators. Pilots aren’t going to look down in the pattern and notice they’re at a critical AoA when they’re slow and/or cross controlling in the pattern. How do I know this?? Because if they were looking in the cockpit they’d see the airspeed indicator is dangerously low and the inclinometer (ball) is slewed out to one side, instead if being centered in the “dog house.” But these crashes keep happening because pilots get slow in the pattern and don’t notice the indications on the instrument because they’re not cross checking their instruments. More importantly, their stick and rudder skills aren’t picking up on the pre-stall indications (seat of the pants feeling) the airplane is giving them, either. Or their stick and rudder skills are rusty and they overshoot centerline and instead of abandoning the approach and going around, they rapidly cross control the aircraft in an attempt to regain centerline with the same disasterous results. So simply adding an additional instrument to the panel won’t suddenly stop these kinds if accidents from happening. Using your old-school stick and rudder skills to feel what the airplane is doing (skidding, slipping) and maintaining an appropriate airspeed for the current configuration will ALWAYS keep you safe. That’s why instructors harp so much on airspeed. Sitting in the ground with the engine running, an AoA indicator will show that the wing is in the safe flight regime. But if you’ve got zero knots, the wing simply isn’t flying. Stalls in GA aircraft occur because pilot’s lose track of what they’re doing and what the instruments are indicating, get excessively slow, and stall the wing. They don’t suddenly exceed the critical AoA without any other indications leading up to the stall and miraculously stall the wing. They get slow and stall the wing; and the ONLY remedy for that is airspeed, airspeed, airspeed. I should also point out that AoA indicators have movable vanes that are mounted to the fuselage that give you a rough average of what the wings are experiencing. If you’re close, but not past critical AoA (according to the indicator) and don’t have the ball centered, you could still stall/spin the aircraft regardless of what the indicator says. One wing will stall first while the other is still flying. That’s why I said before that using an AoA indicator to potentially “max perform” isn’t necessarily a good thing. Imagine you’re trying to better understand relative wind by slowing the aircraft and increasing AoA close to a stall. Since you’re busy staring at the AoA gage, the inclinometer falls out of your cross check of the other instruments. You don’t expect a stall/spin because the AoA indicator says the wings aren’t stalled, when suddenly you find yourself in one because you weren’t in coordinated flight and only one wing stalled, sending you into a spin. My point to my co-pilot was in a big airplane like a DC-10 which has virtually no seat of the pants feel whatsoever, it should never be flown by reference to anything but the appropriate bug speed for the current configuration for the very reason above. When low, slow, and uncoordinated, referencing an AoA indicator alone can lead you down the primrose path to disaster if you think it will always keep you safe from stalling an aircraft.
Agree that its not a panacea. But from my perspective, AOA would still be a beneficial instrument esp. to a student or green pilot. A bad practice would be to fixate on ANY single instrument…I don’t see how AOA would be any different in that case. It seems like it could be beneficial learning tool.
Therefore the aircraft should only have “needle, ball & airspeed” so that the pilot doesn’t get distracted with all those other instruments. While I believe AOA would be beneficial to a DC-10, it would be even more beneficial to the average GA pilot. I don’t believe any instrument be the cause of fixation but see little issue with incorporating an AOA into a scan pattern.
You make a fair point, Dave, and to be clear: I don’t think AoA gauges are bad. I fly an airplane regularly that has one. I just think their benefits are being vastly oversold for light GA airplanes.
With your actual experience with an AOA in a GA plane, your position surprises me. The sensitivity of the AOA to pitch changes dramatically improves the awareness of what the wing sees versus the delay of the ASI. One huge benefit I see in my AOA equipped Bonanza is the simple way it accounts for the load/weight I’m flying at.
When is the last time (since shoulder harnesses) you’ve seen the FAA come out to see it as such a safety improvement the leave the installation paperwork solely up to your local A&P with a simple log-book entry? That’s huge!
Paul, I do love to see the FAA allowing this installation with a logbook entry. It’s a rare example of common sense (although note that this applies only to the Alpha Systems, not the Safe Flight installations).
In the airplane I fly with AoA, the only time I ever look at it is when practicing engine-out glides. In normal operations, I fly profiles and airspeeds.
If AoA gauges were being presented as an emergency tool, maybe I’d feel better, but for the base-to-final stall/spin or the VFR-into-IMC loss of control I just don’t believe they will move the numbers on accidents.
If a pilot wants to put in AoA, there’s nothing wrong with it at all. But let’s not get our hopes up about some major safety improvement.
I own a Cherokee 140 and I have a Lift Reserve Indicator (a type of AOA meter) installed, and I train with it regularly. The AOA meter, once properly set up allows you to train at the bottom of the flight envelope with confidence. The up side is you build better stick and rudder skills by having more training time in slow flight, and using the AOA meter to do so safely lets you experiment with your airplane safely at speeds below the POH recommendations. This is important because loss of control at slow speed in the pattern is a killer!
I have sucessfully executed steep turns (45-60 degrees) with confidence at the edge of the stall, at airspeeds that might suprise you. I have been able to climb on a 60 degree day with two people aboard at 40 MPH indicated on the ASI. And I have been able to make over 250 feet AGL at less than 1500 feet from the roll away point, and made 750 AGL at 3000 feet from roll away. I have been able to train like this because I always know where the stall is and how much room I have to work with.
I train like this because I own a Cherokee and do NOT routinely fly out of 5000 ft runways. Our home airport is 2940 feet and I regularly fly out of a 2100 ft grass strip at 90% of rated gross weight. I need to KNOW that I can operate safely in those situations because my wife flies with me. If you think Cherokee owners never push the limits of their aircraft, I suggest you calculate take off distance on a 2100 ft grass strip on a 90 degree day with 1/2 load of fuel, two people, a dog and 60 lbs of baggage. My personal limit was 88 degrees! 92 was stay on the ground!
The downside of the AOA meter is that it doesn’t do you any good if you don’t understand it and/or you don’t train with it. I know from experience that pilots can get rusty pretty fast. The problem with commercial aviation is that the pilots never train at the bottom of the low speed envelope in those big planes. If they did, the Aisan aircraft accident probably wouldn’t have happened.
You guys who are nay-sayers on the AOA meters are like horses with blinders on. While it is true that better and rudder skills are necessary, and that we need more time at low airspeed training, you are ignoring the one tool that lets any pilot train hard in the low speed envelope with absolute confidence and safety in any airplane it is installed on. I train low speed on purpose. I trian low speed tight on the stall on purpose. I don’t want to guess where the stall is, I want to know where the stall is. I want to feel it in my blood, even if I am looking out the window at a tugboat while I am doing tight turns around it at minimum airspeed. Training like this increases my situational awareness by giving me a better feel of the aircraft at low speed, and it makes me a better pilot for doing so.
There are a lot of people who feel that spin training is a good leg up on this problem, and advocate spin training for this purpose. I would argue that NON-spin training at the absolute slowest airspeed possible is more important, easier to do, and can be done safely in any aircraft if an AOA meter is available. I believe that regular low speed training is the only way to keep your skills sharp and your airplane in one piece.
I suggest you read my article on the AOA meter on wikipedia: http://en.wikipedia.org/wiki/Airspeed_indicator#Variations
I wrote it shortly after installing the LRI in my cherokee.
I love having it and I train with it regularly.
HAVE FUN! FLY SAFE! Pete
There seems to be two camps.
1. AOA instruments can save your life.
2. AOA instruments are a waste of money.
Because of all the press lately AOPA, Flying… (Do these guys get a cut of the sales???) I have been considering the installation of one.
I’m a full believer in stick and rudder flying and see the AOA as a instrument to better learn how close to an issue I may be coming.
Just not sure that I need to spend $1,200 to get that knowledge.
I was thinking the same thing. But then I could do a lot of flying – even with an instructor – for $1,200. That might be a better use of the money.
If you’re not flying aerobatics, I’d say it’s a waste of money to install. And an AoA won’t save your life. If a pilot backs themselves into a corner and almost stalls an airplane and nearly kills themself, the other instruments will have been giving plenty o’ indications long before an AoA would “save their life.” I find it really funny that there’s all this new interest in an old instrument, as if it’s telling us something new and wonderous. I’d liken it to GPS. All it did was make navigating easier. It didn’t change the airplanes, or the environment in which we fly them one bit. They said it would reduce GA accidents by providing pilots with unprecedented information in the cockpit and make navigating a snap. You know what happened?? GA accident rates overall stayed the same, but the number of fatal accidents went up. Why?? Pilots thought this new fangled gadget would manically keep them safe and flew into conditions that violated their own personal minimums they’d developed before the advent of GPS. They were told it would make them safer, but failed to realize that was a sales gimmick and the airplane and the environment we fly in hadn’t changed just because GPS was invented. I see parallels with all the hype about AoA indicators. They won’t prevent stalls or keep pilots from killing themselves.
Your point is valid, ” I’d liken it to GPS. All it did was make navigating easier. It didn’t change the airplanes,…” Pilots still get lost. Even with satellite weather pilots still fly into thunderstorms. With ANR headsets we still miss calls from ATC. We still have too many close calls even with TIS, and let’s not even discuss glass panels. However all these gadgets and gizmos do have there place and with the right training and integration might(!)provide the pilot the information he needs to make flying safer. AOA has limitations, but it also provides benefits.
Bobby, as a primary student or new pilot, you should be focused on learning the basics first and foremost, and building upon that experience. You should also be concentrating at the AoA clues putside the cockpit as well. The AoA gives useless information if you don’t have a firm foundation in using your primary flight instruments and stick and rudder skills; and only then if you use it in conjunction with those primary instruments and maintain coordinated flight. An ILS indicator could be a very beneficial learning tool as well, but instructors don’t teach that during initial training because it’s part of an advanced skill set (instrument rating) and isn’t nearly as important as getting the basics down first. There’s a reason you only find AoA indicators in military and aerobatic aircraft: it’s an advanced instrument for advanced flying. Having an AoA indicator isn’t going to tell you anything you can’t discern from properly interpreting your primary flight instruments and looking out the window at the relationship the wing tip has to the horizon. That’s better than an AoA as it doesn’t cost anything; and as a basic VFR pilot, your attention should mostly be outside the cockpit, clearing for traffic. You’re expressing a sentiment that many new pilots complain to their instructors about constantly, that they want to focus more on the cool gadgets inside the cockpit, when they’re trying to impress upon you that your eyes NEED to be outside the cockpit. You don’t need an AoA indicator to see AoA. Look at your wingtip like you should’ve been taught to, and leave the AoA indicator to aerobatic flight where it belongs.
Well hold on. lets not assume I’m a bad pilot and haven’t learned to fly that way already. I might still find value in an AoA. I won’t disagree that a student should focus on the basics and not on a single instrument but – and set aside 91.205 and V speeds for a moment – can’t the same argument be made for airspeed? Or any primary flight instrument for that matter… That every (VFR) pilot should be capable of good old seat-of-the-pants flying? I don’t think anyone would disagree with you there. Each instrument is there for safety IMO. They provide information to the pilot to hopefully prevent overspeed, getting lost, inadvertent IMC, etc, etc. They are all there to help provide you, the pilot, information. Any one instrument by itself does not make for a safer flight…its how the pilot Chooses to use that information right?. So I think I would find the AoA information useful.
Seth’s comments are dangerous. AOA is a primary instrument to be used in basic instruction as it tells you when your wings are going to fail you. Not all aircraft give you a warning buffet and some snap to a direction with even the slightest trigger when stalling. Airspeed won’t always provide warning as weight and AOB change the reference speed. Looking at a wingtip only helps you determine icing. It will not help you determine how well the wing is performing and if you’re about to fall.
Dave, I’m going to have to disagree with your assertion that having an AoA indicator can make flying safer. You JUST agreed with me on the point I made with GPS and how it didn’t make flying safer, and I think you’re missing the whole point the article and I am trying to make. Installing an AoA indicator is not going to improve safety in GA flying. Period. If you want to spend money on installing one and getting the proper training, go right ahead. But even with training in how to best use an AoA indicator to it’s maximum potential, it’s not going to make you a safer pilot. Only with experience, proficiency, and recurring training makes pilots safer, and in turn, flying safer.
You are correct. We disagree
I’d like to spend a minute or two focused on a slightly different issue. The one thing everybody seems to agree on is that some percentage of pilots are going to stall and/or spin some percentage of their planes, some percentage of the time, regardless of what the instrument panel looks like. That’s why I’d like to see spin and unusual attitude recovery training added to the original, and continuing education requirements. Many pilots never see a spin or even a full stall until it happens by accident, and by then it’s much too late to start learning recovery techniques. I’m just a beginner, but I’ve spent a lot of time in aerobatic planes, with aerobatic instructors. I stall and spin on a regular basis. When it happens I recognize it quickly, and recover from it quickly, because it’s familiar territory. I don’t panic over it, because it’s a been-there, done-that experience. But students are frequently over-protected by instructors who avoid spins, or even fully developed stalls like a plague. This training can produce pilots who see a spin or stall as a boogieman, too scary to face, and impossible to deal with. If they never stall/spin, it won’t matter. But if they do, then this kind of thinking drastically lowers the odds that they’ll recover when some unforeseen event throws them into the realm of the unknown. It is already well established that a false sense of security is a dangerous thing, but I think we also need to realize that a false sense of insecurity can be equally hazardous. Just one man’s opinion….
I agree 100%. Unfortunately it is becoming ever more difficult to find a trainer certified for spins. Most schools simply don’t have the equipment to perform this maneuver.
We’ve debated (extensively) the merits of spin training before: http://airfactsjournal.com/2011/08/the-great-debate-stall-training/
My short answer is this: if we teach pilots very precise airspeed control and good coordination, spin training is superfluous. It’s not bad, just not something I think we should allocated extremely limited training time to.
I’m not so sure that teaching “very precise speed control” does the job. If you’re climbing out and the engine quits at low altitude, precise speed control isn’t the key. Getting the nose down, reducing the angle of attack, whatever you want to call it, is. At low altitude that is very hard to do if all your practice has been up high. I believe this familiar scenario is where the new Redbird type simulators can make a significant contribution.
I hope you are right. I’ve yet to try a modern full motion sim so can’t say if the effect is sufficient. The scenario you mention is a good one to explore.
Maybe. The Redbirds I’ve flown didn’t impress me much in the stick and rudder department.
Regardless, in that scenario, spin training wouldn’t do any good at all. At 200 ft, you’re not going to recover from a spin.
“At 200 ft, you’re not going to recover from a spin.”…and that’s the point. Using the sim to demonstrate the perils involved with “the impossible turn” and that at low altitude and high AOA that decision could be disastrous.
True, what you are trying to do is avoid entering the spin. I’m thinking that the simulator can get one used to the visual image of having to push the nose down and pick the best spot ahead for a landing (probably crash landing depending on terrain) under control. I have not flown the Redbird, but it seems like a reasonable training solution to the problem.
I personally have had an engine failure off the north end of Boeing Field and I can assure you, it takes every ounce of mental energy you’ve got to force yourself to push that nose down in that inhospitable terrain.
I’m still a student pilot, although a bit long in the tooth. Being older I accept that there are things that can kill you. It’s true!
So,I’ve paid a lot of attention to understanding stalls, particularly accelerated stalls because I believe those are what cause many accidents, on landing anyway. Those, of course, are what happens in, for example, pulling out of a dive, or perhaps more commonly, during a steep turn, at low approach speed after overshooting the turn from base to final and trying to get back to runway heading. Low, inside wing stalls, airplane spins, no altitude, and the rest, including you, is history.
I think a lot of people don’t really understand what causes accelerated stalls, otherwise it wouldn’t cause so many accidents during maneuvers so close to the ground. We are all warned about “stalls can occur at any speed”. But I haven’t seen a good explanation as to why. Figure it out for yourself. It’s worth it. It’s pretty simple once you think it through. The ends of the bands on the airspeed indicator mean little when big maneuvers are taken, such as low speed steep turns.
Would an AOA indicator help? Perhaps. But in my opinion it would usually be paid little attention in the heat of the moment so to speak. Close to the ground it might even suggest a too simple correction. Too much going on. Too many mistakes to be made. Better to understand what causes that stall/spin when tightening up too much on an overshoot, or similar maneuver, and just go around. I just can’t imagine paying too much attention to anything, other than the runway, and the ground, and my speed, in the middle of final approach. But that’s just me.
I have flown with AOA in a 182 for 8+ years. Most of that time with a heads up unit mounted on the glare shield near the right side of my runway view. Alpha Systems AOA units have an audio option that let you know when approaching target speed and better yet when departing target speed on the slow side.
The. combination heads up indicator and audio are a plus to me landing consistently on short or longer runways. Indicators buried in the panel offer less value to light piston aircraft when we need to be looking outside. AOA does not do away with stick and rudder skill needs but gives better information over a wider performance range (flap & landing weights).
I do believe the Icon presentation is an excellent concept. The reason is the better correlation between the display and an actual wing’s motion through he air.
This discussion has gotten more heated than I’d anticipated. I concur that media and sales hype of anything – including AOA indicators – will present a warped picture. So we can use a filter when reading claims. Just like with any sales ads.
I have a Reserve Lift Indicator, which correlates to AOA. It presents information that is useful and reassuring for steep turns, take off, and landing. Even Wolfgang Langewiesche’s book “Stick and Rudder” cautioned us that in almost all cases in an airplane, we can get out of trouble by merely easing the stick forward. Unless we’re about to run into an obstacle or the ground. Density altitude and gross weight require different airspeeds for takeoffs and landings, but critical AOA remains constant. What intelligent human being would want to ignore that?
Addition of any, single instrument will not make me a safer pilot; only I can do that. Intelligent use of situational information helps me in that quest. AOA is sure as shooting part of that necessary information.
John Z., thanks for opening up discussions on such interesting subjects.
I like it. I trust they will be customized to each aircraft type ?
I can only speak about my experience with Alpha Systems AOA installation. The installation manual goes into great detail about how to conduct the in flight calibration. Support is also a available via phone from manufacturer.
Thanks for that info Charlie. I was wondering how that would be done. Naturally to each individual acft. Makes sense.
I notice that the most vociferous opponents of AOA indicators appear to be those who have never flown with one. I have had an Alpha Systems analog AOA indicator on the top of my panel, where I can see it just by looking out the windshield, in my 63 P172D for several years and a couple hundred hours. It is not a gimmick. It is very useful–and I am not an inexperienced pilot. I have been flying for almost 41 years, I am a former CFII, and I’ve had aerobatic training. The only reason I have “only” about 2400+ hours is that for one reason or another, I have several lengthy gaps in my flying career.
There is no panacea to the accidents which happen, but in my view, the AOA indicator would go a long way toward reducing the common stall/spin accidents, assuming that it is visible in the pilot’s line of sight and not buried down on the panel somewhere. Don’t knock it until you’ve tried it–and just one flight is not trying it. It’s not a cure, true, and perhaps it is being sold too hard, but it’s a great improvement over airspeed-only indications. Remember, an aircraft can stall at any pitch angle and at any airspeed–emphasize “at any airspeed”.
Cary, thanks for the thoughtful comments. I’m certainly not an expert on them, but I do have probably 500 hours flying behind an AoA gauge. It’s useful in some emergency scenarios, but I just don’t see it affecting the accident rate much. As I say, while a wing can stall at any airspeed, most stall/spin accidents happen at low speeds. If we can’t control airspeed well, would we be any better at controlling AoA?
With the AOA gauge mounted in the pilot’s line of sight, it’s hard to miss its indication that the angle of attack is reaching its critical angle–most typically in the pattern at slow airspeeds. It’s much more obvious than seeing the airspeed indication lower on the panel. My AOA gauge is analog without any aural warning signals, but it’s hard to miss that needle moving into the yellow toward the red.
The “book” stall speeds are based on gross weight. Very often with 4 or 6 passenger airplanes, we don’t fly anywhere near to gross weight. An AOA gauge allows us to fly our lower weight approaches at slower airspeeds with safety and reminds us to raise our higher weight approach speeds to maintain a safe angle of attack. If pilots were taught from the beginning of their training to use an AOA gauge properly, I believe there would be fewer stall/spin accidents.
Have all pilots read and study Stick and Rudder and give a test on it.And that would cut the accident rate. It saved my life when I was a green Pilot.
Why is it relevant that ICON is still a “yet-to-be-delivered” aircraft? Why speak ill of them as a start-up to further your argument? I don’t see how that is relevant.
Having additional information on a key performance characteristic that is largely invisible to the pilot can only help. I’m sure I’ll hear responses regarding pilot overload and how this can be ignored in the cockpit. That’s not an issue of the value of the instrument, but rather training and choice.
I don’t *need* a tachometer in my car. But if it is provided, and i choose to use it, it serves a purpose.
It’s relevant because nobody outside of ICON has flown the airplane yet. I’m not saying they won’t deliver it – in fact, I’m really rooting them on as I think it’s a great-looking airplane. But so many airplanes are truly judged when they get in the hands of everyday pilots instead of test pilots and engineers. We all learn a lot after the first 10 airplanes get delivered. Until then, any discussion about the AoA instrument in the A5 or the handling qualities of it is speculation.
I agree with most everything said. I do wonder why the FAA is apparently so gung-ho about it. They usually sit on everything and study it for years before doing anything. It would be kind of fun to play with it at a safe altitude to see if it really helps much. Thing is, though, if you fly the correct airspeed and stay away from steep turns at low altitude you can’t go wrong. But just about everyone that has one swears by it.
I flew my 182 over to Kansas City and spent a day with two FAA types giving them a chance to inspect and fly and quiz me about the Alpha System AOA. They had already spent going over the manuals.
We went up to fly and go through the flight calibration procedures to show them how to accomplish the procedure.
We talked more and they went away with the information to discuss internally. The result was the c’mon sense letter authorizing installation.
One comment on all you need to do is monitor speed and don’t bank too steep. I used to own a high performance six place single (Piper Lance). The difference between flap up stall max gross vs full flaps min weight was 21 knots. I bring this point up to show that one speed does not fit all situations.
The stall warning sounds between 5-8 knots above stall. The AOA target speed is 30% clean and just under 40% stall at flaps 20-40 degrees with the Alpha calibratiom. This to an approximate 12-15 knot margin above stall. A turbine aircraft’s ref speed is 30% of stall at the landing weight. The 5 knot aircraft system stall warning may not be enough to respond with enough time to recover close to the ground. Flying a 182 at 1.3 (30% over) stall is 65-69 knots IAS in my Horton STOL modified Skylane. This gives margin and consistency you can achieve no other way.
I worked at Citation Marketing for 14 years and got the worlds best training from many great demo pilots on how to use an AOA system installed in Citations.
Sad to say though that Flight Safety does not offer much insight into AOA.
Fly Safe everyone. AOA works.
Like most flight information, the issues associated with AoA are not simple and depend heavily on the airplane type, its intended use and the knowledge of the pilot. I’ve designed commercial jet flight decks for over 30 years and have been asked (or told) about the advantages of AoA numerous times. Examining the research work that we have done, as well as reports from NASA and the Armed Services, I conclude that AoA information can be useful but the form in which it is presented makes a big difference in how successfully the pilot will use the information.
At one extreme is the high performance fighter jet with a thrust to weight ratio approaching or even exceeding 1.0 and a highly trained pilot. At the other end might be a piston twin operating on one engine. In this case the thrust to weight ratio is very low. In the case of the fighter the airplane can accelerate over a wide range of flight path angles. When the thrust to weight ratio is low, acceleration may well be limited to descending flight only.
In the case of a high thrust to weight ratio airplane a direct readout of AoA can be useful throughout the flight envelope.
For the low thrust to weight ratio airplane, speed control is everything. Once the airplane is a condition approaching stall, the pilot’s only practical option is to descend to gain speed. If the ground is close by, the pilot may not be able to pitch down enough to regain speed. In this case AoA information may still be useful but it should strongly encourage the pilot to focus on speed control and it should do that before a near stall condition develops. Instead of showing AoA directly, showing the current speed margin to stall is more likely to encourage the necessary power increase.
The other factor to consider with low thrust to weight airplanes is that the wind can change speed much faster than the airplane can. An approach in gusty wind conditions should be flown at a faster than normal speed to provide sufficient speed margin. For those AoA systems that assume a nominal approach AoA is always correct, this is more difficult to achieve.
Interesting that you cite high thrust to weight fighters as needing AOA and yet think light twins with potential engine loss don’t need it. The fighters don’t use AOA for high speed rocketing around but rather for approach and slow flight which all aircraft do. What is interesting is that plane like the Hornet don’t have a published Vmca but they do have a maximum single engine AOA. And while landing at the field with gusty winds, many a Hornet pilot will reduce their AOA by half a degree to a full degree thus generating the margin to which you speak in the same manner yet need not think about adjusting the number in the approach turn. And that same Hornet with a lost engine very well may find itself low on thrust to weight with level or descending flight its only option though the crew would seek to lessen the AOA rather than add knots.
Of course high performance fighters don’t use AOA at high speed. The reference to high thrust to weight addresses the pilot’s ability to get out of a deteriorating condition at low speed. For virtually all low thrust to weight airplanes having extra speed is the only friend the pilot has when low altitude wind shear is changing the airplane’s airspeed faster than that airplane’s engine can.
It is certainly possible to get the extra speed by intentionally reducing the approach angle of attack or by adding speed to the published approach speed.
Once the airplane is in a situation where engine power is not enough, then AoA would be an excellent tool to avoid ground contact as long as possible; with luck long enough to get out of the shear zone.
My point is that there isn’t a single magic solution here. The pilot must remember that both angle of attack and power need to be managed in any crisis situation. There are a number of accidents and near accidents where power was never advanced, not advanced far enough, or advanced too late.
One must first break the AOA prior to adding power in this single engine situation else one departs and that high engine thrust only exacerbates the problem. How airspeed is better at avoiding this as compared to AOA, no one can explain.
The airspeed indicator has much better resolution and sensitivity at approach speeds than any AoA units available to GA. You an easily see that you lost 2 knots off target approach speed with an ASI, but not with AoA.
AoA units improve in sensitivity once closer to stall, but then its already too late.
They make great stall warning devices, but are not good for primary control.
The obvious point to the article was to make current and potential pilots realize that there is another tool out there that has the potential, if used correctly, can provide another safety tool in the cockpit. A competent and current pilot with the standard 6 instruments in his panel will always trump a pilot who isn’t competent, yet has $30,000 worth of gadgets in his panel. AoA indicators may nor may not become the next “thing” pilots want in there panel. Its just another tool they can have at there disposal to make them a better pilot in the circumstances they traditionally fly in. ADS-B installed in aircrafts has loads of obvious safety features.
It may or may not have helped Asiana. I can tell you for a fact, it would have prevented Air France 447 from crashing. The pilots would have an absolute visual indication regardless of the condition of the pitot tubes, where the airplane was in terms of aerodynamics I have flown transport category aircraft both with and without AoA. I cannot tell you how many times the AoA said “You may think you are flying Vref+5, but I say you are very close to stall.” Load audits have always shown, the airplane was heavier than advertised. AoA gives a no BS result of where the airplane is in the aerodynamic scheme. I can also tell you it was with an AoA equipped airplane, I discovered how profound the change in AoA was when the airplane was flown in rain versus dry conditions. Simply put, it does not lie.
GA aircraft can benefit greatly, because of the narrow range of airspeeds over which the airplane fly. 30% of Vso is a lot smaller number if Vso is 60 versus 120. The average GA pilot has far less margin in terms of speed to play with than a large transport pilot. Additionally it is lot easier to overload in gross percentages a light aircraft than a transport. Regardless of how overloaded the aircraft is, the AoA will indicate properly and provide a margin of safety if the pilot is errant in his load planning.
Finally AoA provides very precise control when landing on short fields, which results in shorter landing runs and roll outs. To dismiss this as some “new fangled” thing is like saying we should throw out the ball of the slip skid indicator in favor of a silk scarf. Sure the scarf looks cool, but is it really the best and most precise way?
I am not convinced the Air France 447 disaster is relevant to a discussion of AoA indication in GA aircraft and risks going off topic. However, the crew received more than 70 audible warnings of stall. The investigation highlighted high levels of cockpit stress with much visual information that perhaps they did not hear the audible warning. It also importantly concluded that they received “very little [exposure] to stall situations” in their training. Perhaps another AoA in-cockpit visual reference would have done little to resolve the situation over specific exposure to stall recovery in training.
I think AoA may be most useful for precision STOL situations, primarily in tail-wheel aircraft and especially in making off-field landings. It would be interesting to use it in craft such as Just Aircraft Superstol. Anyone have any experience of this?
The top “solution” item in the BEA report of AF 447 was what? Need for an AOA. The crew thought the stall warning was a result of bad airspeed, when in fact the stall warning was the result of AoA measurement. AoA was both measured and computed, but not presented on the Airbus, except when the airplane was stalling. If it had been presented the crew would have seen conclusively that the AoA was as much as 35 degrees and done something about it the secure knowledge that AoA has no relationship to airspeed.
If you look at the most frequent excursions from normal flight envelopes by professionally flown airplanes right now, based upon FOQA data, believe it or not, it is stalling the airplane.
Maybe. I think you could argue those pilots needed less information, no more. They were overwhelmed. Power and attitude would have saved the day.
…if not training.
Anyone flown an AoA indicator into short landing scenarios in the bush?
That depends on your definition of “in the bush”. Annually I fly into a grass strip in a canyon near Marble, CO, at 7800′. Here’s my Youtube videos of going in and out: http://www.youtube.com/watch?v=iGAN6pDYt_4. http://www.youtube.com/watch?v=LPNaGwZ2fA8
Sorry about the poor video quality–a videographer I’m not.
Having read the article and some of the comments (not all) it is obvious that most of the folks arguing against the use of AOA gauges and an approach indexer do not understand how they work and what they can tell a pilot -instantaneously.
As a retired Marine Aviator with carrier operations experience in the F/A-18 and T-45, I spent most of my 3,000+ hours living not just on the amber donut on the approach indexer and the AOA bracket in the HUD, but on the AOA gauge, too. What is my max endurance speed? 5.6 true AOA in the Hornet, 14 units AOA in the T-45. Max range? 4.3 true AOA in the Hornet, 12 units AOA in the T-45. Final Approach speed? 8.1 true AOA in the Hornet, 17 units AOA in the T-45. Don’t get me wrong, specific airspeeds were calculated for each of the AOA readings, but the NATOPS Manuals (POH) for both of these aircraft listed AOA readings as back-up airspeed indicators in the event of a pitot static system failure.
As for the stall/spin in the landing pattern, I ask what is easier to read – especially at night – a small number on a display or the end of a needle or color coded indexer mounted on the glare shield right in the pilot’s line-of-sight? Amber donut and I am on-speed for my configuration. Amber donut with a green chevron? Lower the nose/trim nose down. Amber donut with red chevron? Raise/trim nose up. It’s so easy even a Marine can do it!
That’s the one thing I’m missing, lighting on my AOA for night ops, since my analog version isn’t lit. The rest of my panel is well lit with Nulites as appropriate. I have a Mic-Light on my headset boom, which helps, but I need to figure out how to adequately light the AOA indicator.
After a few years of flying with my AOA indicator, I tend to use it as the primary and the ASI as the secondary instrument on approach. I gather that’s pretty much the military way as well.
You are exactly right. You compute your final approach speed prior to pattern entry. As you are configuring for landing and slowing down, you are watching the AIS as you reach on-speed to make sure the AOA indicator system is functioning properly. If they marry up, you are flying the indexer the whole way to touch down.
Just out of curiosity, what are type of aircraft are you flying?
Robb, I love that you remember these numbers. Anyone else, realize orange donut is the Navy way and Air Force and civilian instruments and indexers may display differently. Though the concept of one number at any weight and angle of bank is true. Think how many students have crashed in T-38s because they had different numbers of the perch, around the turn, and on final while the T-45 had one number from the abeam to trap.
“ANGLE OF ATTACK ISN’T A MIRACLE CURE” ? SO HOW WOULD YOU RATE AIR SPEED INDICATORS, PLUS STICK & RUDDER SKILLS ?
YOUR G.A. INTRODUCTION TO AOA, REMINDS ME SOMEWHAT OF THE PREJUDICED RECEPTION TRICYCLE GEARED AIRCRAFT RECEIVED IN THE LATE 1940s. (at 87 I remember).
AIRSPEED IS BASIC, BUT AOA IS GREAT, SHOWING, AT YOUR ATTITUDE, WEIGHT & CONFIGURATION, WHERE YOU WILL STALL – A SAFE MARGIN.
AMAZING IT TOOK G.A. SO LONG, WITH COMMERCIAL/MILITARY ROUTINELY SAVING LIVES FOR EONS……
NOTE: MOUNT THE COLORFUL, HIGHLY GRAPHIC, IN PILOT’S LINE OF SIGHT.
Dick, as I said, I don’t think AOA gauges are bad. I fly with one and it works. What I do think is bad is for aviation experts to believe that they will somehow make a huge impact in the fatal accident rate. Did tricycle gear eliminate landing accidents? Most of the statistics say no, not even close.
I have enjoyed this spirited debate and am absolutely astounded at some debater’s virulent argument against AOA indicators; especially you Seth. The most absurd and dangerous thing you said was that we should judge our angle of attack by looking out the window at the wingtip. That statement is exactly why you especially should have an AOA. Angle of attack has absolutely nothing to do with the horizon, as I thought every pilot should know. Especially on climb out or approach. As every pilot should know, angle of attack has to do with airflow and airfoils, not the horizon, whether it be flat or full of mountains, daytime or night.GOOD GRIEF.I am in my 52nd year of flying and 13,000 hours in everything from a Gyrocopter to B-727s and I am lusting after an AOA indicator. I normally would not be so willing to disagree with someone by name, but that is a dangerous statement to make in the light that someone may take it to heart and pay the price.
Everyone feel better now that they have expressed their opinion on the same old subject? Grow up people, no instrument will keep stupid pilots from doing stupid thing. Less computer time more flying time.
Despite all of the comments pro and con, I would bet my next paycheck that if the cost of purchase and install wasn’t more than say $600 the number flying would more than double within one month.
Not likely that the price point will get that low, but with competition from several purveyors, it might not get higher than the present (that’s basic “aviation expense” rules–prices just don’t go down–the reason we use AMUs, to fool ourselves into thinking we’re spending less than we are).
My view is a bit warped after all of these years, perhaps. But although I have BAS retracting harnesses in my airplane in lieu of its standard seatbelts only, I prefer to reduce the possibility of an accident than just equip to minimize the effects of an accident. Whether equipping all GA airplanes with AOA gauges may or may not reduce the accident rate can only be determined if all GA airplanes are so equipped, and if every pilot is trained from the beginning to properly use the AOA gauge. Meanwhile, I’m convinced of the utility of having one.
BTW, that anyone who has passed his/her pre-solo questionnaire could say with a straight face that AOA can be determined by looking at the wingtip’s relation to the horizon truly amazes me. I don’t think I had 3 hours of flight time before my instructor drilled into me that a wing can stall at any airspeed and at any pitch angle, and when I was instructing, I did the same thing with my students. I have no doubt that many go through their training without that fact being demonstrated to them, but it’s not hard to do: a descending spiral with excessive backpressure will create an accelerated stall with the nose pointed down, as will a steep dive with too vigorous a pull out, and neither needs to be at a particularly low airspeed.
Read this if you want to understand some limitations if AOA indicators.
Love all the speculation on both sides,lol. What really stands out is how incompetent you think the pilots and the instructors that trained most of us are. Also that the system in place is no where near adequate to keep the average pilot safe. Maybe the FAA needs a wake up call about training, then only a select few with built in airspeed and AOA indicators in their sensitive butt could be pilots .
Hihihi, je savais pas que photoshop fournissait des originaux ???!!!!DÃ©solÃ©e, j’avais juste envie d’Ãªtre un peu mÃ©chante, les gens sont trop gentils sur ce blogs
ZIMMERAN’S & OTHERS “HOW HUM” ATTITUDE TOWARDS AOA KEEPS
URGING US TO RETURN TO LANGEWIESCHE’S TEACHINGS IN “STICK &
RUDDER,” A VALUABLE PRIMER PUBLISHED IN 1944….SERIOUS READING
HOWEVER, TRAINING BASED ON HIS PRINCIPALS, NOW STILL POPULAR
FOR 72 YEARS, HAVE NOT SUCCEEDED IN ARRESTING OUR UGLY
RECORD IN LOSS OF CONTROL FATALITIES.
COMPARE INDICATED AIR SPEED W/ AOA IN A 90 DEGREE STEEP TURN
@ MINIMUM APPROACH AIRSPEED.
THIS REVEALS SURPRISING & SUPERIOR AOA INFORMATION, AS TO THE
ACTUAL POINT, WHEN WE WILL STALL. KNOWLEDGE FAR MORE
CRITACLE THAN INFO THE AIRSPEED MAY PROVIDE. AOA PROVIDES
A GRAPHIC WARNING – YELLOW MOVING TOWARDS RED, A
UNIVERSALLY UNDERSTOOD LANGUAGE.
DICK BICKNELL, AOPA 9017
What is with the caps. Maybe it will be like seatbelt usage people drive more reckless with belts on because they feel safer. So what makes you think that they won’t fly right to the edge all the time.
So why would you be in a 90 degree bank at minimum approach speed?
Conventional (and aerodynamic) wisdom dictates no maneuvering once at minimum approach speed.
John Zimmerman, and other very experienced pilots, have been attempting
to teach us stick & rudder skills since day one…..
Perhaps it’s time to recognize the Ercoupe’s behavior.
I completely agree with Zimmerman.
I use some very expensive AOA probes during flight test (military and civilian) but do not use one for everyday flying. I don’t even have a stall warning system in my experimental. If you understand the relationships between weight, load factor, and airspeed, etc., you can set minimum speeds for maneuvering in the pattern that will keep you far away from stall concerns. At that point, the AOA unit is a mere curiosity. If you set minimum speed on base to 1.5 Vso, you can sustain 2.25 Gs. Then 1.3 Vso on final still gives you 1.7 G capability. The key is to fly the numbers and maintain zero tolerance for dropping below minimum speeds. My personal tolerance is +2/-0 KIAS. If you are spending time looking at another instrument, you are not looking at the ASI and your speed control suffers.
I saw the F-4 mentioned above. Those displays used for approaches only show a tiny 2 degree range centered on the approach speed. They aren’t there for stall warning or any flight maneuver other than final approach. Airspeed targets are flown until on final. These AOA units are also much more accurate than anything you can put on your Cherokee or Cessna, partly due to design and partly given the high approach speed of military jets.
While the author’s view that AOA is just another instrument is fact, its use is much more than just another instrument to scan. Airspeed may provide a substitute for AOA but one must compensate for both weight and angle of bank when relying on airspeed. As AOA only needs one number and simplifies these concerns, it is substantially better. This is true for stall, approach speed, best endurance, and best range. AOA can, however, be in error should the AOA probe freeze or jam so cross checking airspeed is still good practice. The author’s example of the SF crash as described in the article is a poor example of AOA as the author mentioned no one was looking at any instrument hence airspeed wouldn’t be better either. An example where AOA could have saved the day is the Air France crash from Brazil in a massive thunderstorm whom had experienced frozen pitot systems. AOA, both from the probes and INS derived, would surely have told the crew they were in a stall for the last 30 thousand feet while airspeed showed them fast had they been taught AOA as primary. AOA is safer. AOA is better. Airspeed should be the cross check not primary. Now standardizing display of AOA needs to be addressed as the Navy and Air Force both differ from each other and likely from civilian means.