Aw Gee Eddie
 

The actual name of the pilot with the great Code7700 website is James Albright, aka "Captain Eddie". The pseudonym Eddie Haskell is based on his USAF call sign. A very well organized site with much useful info.

As a 3000+ hour fighter pilot, I think this is an interesting thread. As a guy who also flies GA and now for an airline, let me ask the group this: what is the largest cause of GA crashes? Of all crashes? Is it mid-airs, or low altitude stall/spins? I would say the latter, yet the FAA is requiring ADS-B. If they were truly concerned with saving the maximum number of lives, AOA gauges and AOA instruction in training aircraft would benefit all pilots greatly.

The simple way I think of it is the wing flies by AOA... It doesn't care about airspeed! When teaching aerobatics in the T-6 to a friend who has 13,000 hours (mostly on floats and no jet time), we had lots of discussions about AOA, unloading the wing, how you cannot stall below stall speed if you unload, etc.

ADS-B has nothing to do with GA safety, it's about improved air traffic management which has an aspect of protecting airliners from GA (but not GA from themselves).

I agree that AoA certainly has potential for GA, but current GA flying techniques (and training & testing) evolved based on other instruments. Individual GA users who have the inclination can certainly acquire and learn to use AoA instrumentation. IMO (and only my opinion) applying it broadly across all GA would require big changes from the ground up, which would be opposed by various interested parties due to cost.

AoA is a getting a more direct answer to the question at hand, but you can still get the answer through other instruments...if I'm flying the proper profile I already know what AoA is going to tell me (except in icing). It would probably be easier for private pilots to scan just an AoA gauge and the runway in the base-to-final turn, but it's probably too politically challenging and costly to mandate AoA. But no reason individuals can't take advantage of it, as long as they commit to learning and using it correctly...otherwise it's just another dust collector, and possibly a distraction.

The one instrument I never trusted much in single engine G/A airplanes was the airspeed indicator. Luckily it usually reads low, not high, if you've got some dirt or a bug in there.

Even if it's clean when you depart, all it takes is one unlucky bug into the pitot tube and it's gone, so you'd better learn how to fly without depending on looking at the airspeed indicator the traffic pattern.

This is why I really liked the "Bacon Saver" AOA vane mounted on the left wing strut. I never had to look inside for airspeed in the pattern.

If your first statement is true, then, how many airliners have had mid-airs with GA aircraft? And, if ADS-B is for traffic flow, I am ignorant of why Mode 3/C is insufficient. Mandating ADS-B in all aircraft will not increase safety, yet mandating AOA would absolutely decrease the number of stall/spin accidents, from what I understand is the #1 killer of GA pilots.

And I agree that mandating AOA in airliners would probably not be required, since we fly in the meat of the heart of the envelope.

Actually, though, the FAA, as well as some of the GA organizations, from what I understand, are "highly encouraging" AOA gauges in GA aircraft, as they see the value in it. Again, if you have not flown with it, you probably think the wing stalls at a certain airspeed, but the wing cares not about airspeed ... It flies by AOA, so why shouldn't we?

Cricket, you flown the NAT Tracks and all over Europe much, in an airliner?

That's why ADS B is being implemented.

I fully agree with your views on AOA.

??? Several, which is why TCAS came about.


Yes, it is for traffic management and replaces the functionality of secondary radar (ie mode 3C on the airplane end) and adds some capabilities. Presumably secondary radar will go away. I would welcome an improved version of mode-C because it is not entirely reliable. ADS-B will be inherently more reliable in that regard.

Correct. But NOT mandating ADS-B would significantly decrease safety since ADS-B will presumably replace mode C, so non-participants would be invisible...unless they maintain the mode-C and secondary radar forever which is probably not the intent.

I agree, but it wouldn't eliminate stall/spin accidents...many of the folks who fixate on the TDZ and pull & bank until they stall/spin won't be paying attention to the AoA. There would be some benefit, but it's hard to quantify.

It would be expensive since you'd have to equip all aircraft and re-vamp the training system...if you don't train them, they won't use it right. But the real issue is political will to do it...unless AOPA, NAFI, and the NBAA decides it's worth it, the FAA would be fighting an uphill battle on this one. Without AOPA on board, it would be no-go. The FAA knows this.

It's up there but I think CFIT or loss of attitude control in IMC is the leader.

I'd mandate that first since it's useful in bad icing.

I'm all for encouraging it, especially for the savvy GA pilot who can make good use of it. But it's too much cost vs. benefit to try to mandate for all GA (I think).

Unproven conjecture, possibly true, but you might be surprised. Loud stall warning horn/ lights don't prevent stall/spin accidents. Glass cockpits with big stall regime warning (would be very easy to get a "derived" AOA in a glass cockpit with AHRS) don't prevent stall/spin accidents.

Ensuring a high level of mastery of the aircraft would likely reduce stall/spin. All GA pilots (well, all pilots) should be very familiar with the concept of AOA.

Mandating yet another gauge on GA craft is very much the wrong way to go.

I'm honestly not sure if you are being sarcastic or not. Airliners routinely fly quite close to the edge of the envelope in Q-corner... are you talking about something else such as structural failure?

You're taking me way back to aerodynamics and fluid dynamics.... No GA pilot has to know what mach tuck or flow separation is, or why airliners and the jet jocks have swept wings.

As far as I know AOA sensor is MEL on most modern airliners and absolutely critical. I wouldn't want anybody trying to hand fly at FL410+ for long.

GA pilots in our thick air are generally nowhere near the limit of the flight envelope for essentially all aspects of flight.

Because:

1. Most of us are not fighter pilots doing high-G maneuvers at risk of accelerated stalls at the edge of the flight envelope.

2. Getting more FAA / government mandates is generally a very bad thing.

3. Installing things, especially certified things, costs a lot of money.

4. With a bit of education most GA pilots can understand the concept of AOA, lift reserve, accelerated stalls, etc., and if they want to go ahead and install a sensor they can do so.

+1 to what RickAir said didn't read his post first.

You can just search for the latest Nall report if you are interested in why GA pilots crash. It basically depends how you classify things. The number one cause of incidents is mishaps when landing. Pretty consistently the number one cause of fatality is variants of disorientation and VFR into IMC and CFIT, then number 2 is maneuvering flight like that video link I provided awhile ago.

Simple things that flight instructors can teach to help prevent stalls and understand AOA without needing an AOA gauge:

1. Explain the relationship of bank angle to stall speed increase in a level turn (these are within about 1% accuracy, and easy to compute)
30 deg = 10% stall speed increase
45 deg = 20% stall speed increase
60 deg = 40% stall speed increase

2. Have the student note where the yoke/stick is when the aircraft stalls. This will be the yoke position required to exceed the critical AOA at any speed and weight (assuming configuration stays the same). Also note the difference in yoke position to stall the aircraft with flaps up vs flaps down.

3. Practice accelerated stalls with the student after noting the yoke position required to exceed the critical AOA. This will reinforce point #2.

I just read another interesting article. For anyone interested, look up "Aero 12 - Angle of Attack - The Boeing Co." (This is from Boeings quarterly news)

Modern GA training aircraft are designed to have little further aft movement of the yoke past the critical AOA position. In this sense they are close cousins to the Ercoupe, and I think it somewhat hinders the instructor from training stalls. I find it very difficult to stall a Warrior or a C152 power-off/level flight and keep it stalled.

The Warrior stalls pretty docile, though I always thought a 150/152 stalled with a fairly noticeable break. I wouldn't exactly refer to those aircraft as modern either! Did you learn to fly in a Bleriot?

Wright flyer.

And while yes, you can do math to get an approximate stall speed vs AOB, why do public math? Especially in the pattern.

Also remember, stall speed is predicated off of a slow decel rate as well.. You whip it over to 60 and pull, and it's going to stall at a higher speed, even without an abrupt pullup.

Of course, do this with an AOA gauge, and you can see the transient high AOA before speed and AOA come back to jiving with each other.

In dynamic flying, I trust my ass more than airspeed, and I trust AOA more than both of those combined.

Airliners and most GA never get all that close to stall speed in normal operation. I think (don't have proof) that the 1.3 Vso = Approach speed came from all the safety factors they have to put into making sure approach speed stays well above stall, with all possible airspeed and aircraft weight/cg computation errors, plus allowances for gust and turns.

I'd be comfortable flying at around 1.1 Vso with an AOA gauge on approach. I used to do it somewhat regularly. In a big plane. To a moving target.

Speed is energy. Energy dissipates from planes in three main ways.
Aerodynamic Drag (friction)
Brakes (more friction, with a bonus of heat retained on the airframe and possible fire if bad enough)
Reverse Thrust

Any kinetic energy not absorbed by one of the above tends to get arrested by the ground, which is technically a form of braking, oftentimes called a crash.

Landing slower, but above stall is generally safer and easier on the equipment. Hence why we normally land and takeoff into the wind.

I have no problem taking King Airs with AOA systems into absurdly short fields. (granted, VMCa usually becomes my limiting factor before AOA, but yeah, slower is better when landing rough and short)

C-152 power-on often has a wing-drop. Power-off clean it will just oscillate as the nose barely drops and it immediately recovers with the yoke held full aft. This type of "designed-in safety" doesn't help to teach what a plane handles like in a full stall, although it does keep most everyone alive...at least until they get a license and move to another aircraft.
I guess you're right, the C-152 and Warrior are both old. But, the only modern GA trainers besides the Diamonds are the LSA type aircraft. Our Van's RV-12 is great for teaching stalls, far better than the C-152/Warrior.

E2CMaster, I have no idea what you are talking about here. When you "whip it over to 60 and pull" it will stall at about 140% of your normal stall speed, assuming you are in a level turn. The level turn is just so you aren't pulling more than 2 g's (load factor at 60 deg bank) which I guess you would be exceeding if you had an abrupt pullup instead of maintaining level flight. The abrupt pull-up or any stick pulse past the position of critical AOA will stall your wing, and it will do it immediately, you don't have to wait at all for anything to catch up.

Teaching students the stall-speed/bank angle relationship is just so students know why we don't bank excessively when trying to keep from overshooting final (You can do the math on the ground, that's where I teach all my math). You can bank 90 deg and not stall as long as you don't pull, and if that's what you are saying, I understand. That was my point about the stick/AOA relationship. The plane will always stall when the stick/yoke reaches a certain aft position -- whether you are fast, slow, level, banking, inverted, "maneuvering dynamically", or just slowly decelerating. The AOA gauge will confirm that.

Every plane (except a few, most notably the Airbus) has an "AOA gauge" -- the yoke or stick. Until you get to a deep stall, that relationship between stick position and AOA is very direct.

I still rely on buffet to indicate a stall, but many planes don't give you much buffet. Many swept-wing transport aircraft will just have a hard time keeping the wings level during a stall, but won't give typical GA-like buffet, and just about all jets rely on artificial feedback/feel -- the loss of which is one reason a DC-10 crashed at O'Hare on takeoff in May 1979. Here's an interesting case of USAF test pilots (who knew they were going to be flying in a slow-speed regime that day) stalling a plane for thousands of feet before they realized it: Cargo Jet Nearly Fell During Test - Chicago Tribune

The A-10 has a straight wing, but had very little change in buffet when you exceeded the critical AOA -- the nose track just abruptly slowed way down, which was easy to tell and self-critiquing during BFM.

I think if the pilot of AF447 had a better understanding of why planes stall and how to recover, he wouldn't have been pulling back on the stick the whole time as he descended 35,000 ft to the ocean. If he had trained with an AOA gauge early in his career, it may have cemented the relationship enough for him to have known what he was actually doing.

The only substantial argument against across the board AoA adoption I have read here today is the one about it being a cockpit distraction. All the other ideas are problems that can be solved or mitigated. The military does not find it much of a cockpit distraction from what I understand, and going out on a limb a little bit I think if you require AoA in all new primary training aircraft and thoroughly revamp the FAA primary pilot training liturgy the same way it was revamped for glass cockpits a few year ago, you could remove a lot of distracting material and replace it with AoA awareness techniques in lieu of a bunch of other training tasks. At any rate, tests can be done with and without the AoA instruments in ground sim to see whether they are distracting or not.

I would vote for a suite of 4 gauges rather than one, because until you know left & right AoA values for both tail and main wing you really do not have an adequate picture of the global lift regime. I also feel the present crop of dumbed-down retrofit AoA gauges without number scale are the right approach. It's too much like an idiot light in a passenger car, just another black box warning to disregard. A fairly accurate number band with color designations is the best presentation in my view, and it can be digitally enhanced to include attitude corrections the same way virtual attitude indicators shout messages to the pilot in unusual attitude scenarios. I would not argue for mandated inclusion in existing aircraft due to expense mostly, but you have to start somewhere.

I think there's an extremely valid argument against "across the board AoA adoption" in the sense of a value proposition for a retrofit mandate for the existing fleet.

If Part 23 gets revised to require AoA in the future, more power to it and it would be a good thing IMO. But requiring Joe Sixpack to put an AoA on his Cherokee 140 would be of questionable public benefit for the expense induced.

Great posts, Fluglehrer.

I'd add that in my 182, it will drop a wing very aggressively with a nose-high power on stall. Have to be prepared, and this is one of the reason that high performance endorsements are needed - if you are not quick with the rudder you will be pointed toward the ground in a half spin, (which it will come out of into a dive).

Secondly in addition to below (all of what you described is Flying 101 well, maybe Flying 102) I'd have the student practice the falling leaf to get a good hang of the rudder control. It is actually a lot of fun too.

None of the aircraft mentioned so far as "wing droppers" drop a wing in a power off stall when coordinated. I have noticed with each of them that just before the stall, almost no right rudder is necessary to keep the "ball" centered, except, if you look at the ball trying to do this you'll never react fast enough and the will will drop because you had too much right rudder in or in rarer circumstances, not enough. This is only just slightly before the moment of stall, after lots of p-factor at the high AOA, but it's allowed me to bring the yoke back to the stop while in a power on stall with the wings level while the nose drops down. It doesn't like to stay like this though and IMO you have to look at the horizon and see the yaw, rather than the ball.

I think AOA would be extremely useful, and the whole point is we don't know what joe Cherokee will do, loan his plane to a new pilot, lease it, etc. I don't have much to add here, except that teaching the concepts in this thread is much easier said than done. The AOA would help immensely. We could probably get by with far less stuff in the cockpit if the training was adequate.

Really? I never really used it for landing and came down fine every time. Still nice to have though

JNB and wing-droppers
 

I think what most people (including me) mean is if you do nothing when the plane stalls it will roll off on one wing, keeping coordinated requires very active rudder input which is part of the coordination exercise, which as you said is changing due to rapidly diminishing AOA and p factor effect. If you remain coordinated it will keep nice straight and level, and even if one does nothing and it rolls off through the stall break it won't continue to spin.

In a 172 though you could have your feet on the floor through the power on stall and it won't be that bad, NOT true with the 182 which will have a very asymmetric stall and come out significantly off heading with a kind of quarter to half-turn incipient spin.

I have done quite a few stalls under the hood but never any intentional spin under hood. Agree with stalls ball still works but it is really hard to be perfect. All aircraft I've ever spun have had no AI as they would likely tumble anyway.

As many other people noted though there is a difference between people that think about this sort of thing and those that don't, or perhaps those that feel that AOA is an advanced concept that needs to be "taught". Also the ones that are most at risk probably are not spending their free time talking about nuances of aviation. :o

You have clearly never had a good AOA system in a light aircraft. The modern systems are tremendous safety aids. That is why the FAA has recently dropped the normal onerous certification rules. They want them out there and installed. There are far to many GA loss of control accidents. The new systems are simple to use and don't require much training. At a minimum almost any pilot can understand what "angle! angle push push means" and take action. He can also instantly establish proper approach speed and best glide speeds regardless of AC weight.

Disagree in theory at least, which is a good thing, because what starts in the abstract quickly becomes first nature if you use it a lot. To ride a bicycle you might first see somebody ride one then you talk to them about what to do when you get on a bike, take some coaching with training wheels installed for a while, remove the wheels so all the physics are in play and then after a few days of crashing and experimenting you get the hang of it and ride it until the day you get epilepsy. There are so many tasks that private pilots do that can use this approach. A few off the top of my head-

• choosing an approach speed precisely suitable for the type of approach you're doing, whether short field, soft, IFR etc.
• steep turns, tweaking of pitch inputs
• varying Va according to weight
• varying best endurance and best range speeds to actual conditions
• seeing stalls coming before they happen, and insuring adequate recovery
• adjusting speed for icing effects
• choosing correct pitch attitude to ace a long list of commercial and ground reference maneuvers
• choosing best rate of climb and best angle of climb attitudes
• making safe base to final turns in crosswinds
• making safe evasive maneuvers at low altitude
• making smooth landing stalls

The list goes on and on. AoA is essential in flying accurately and safely.

Exactly my point too, and the value would be felt in just about every aspect of primary training up to CFI levels and might even be useful in airline flying. I think you could possibly dispose of many v-speeds and substitute AoA targets instead which would be far better than the former, because AoA is what v speeds try and accomplish in most cases.

I would change this to read regardless of AC or weight. The beauty of AOA is every aircraft has an appropriate one and you don't have to remember what it is.

Again AOA is simply a way to display "feel". Were you taught feel? Perhaps the fact that they aren't spending free time talking about nuances is a good reason to include a "quit pulling idiot" guage.

I'd hope so. Was I taught feel? What else are you taught when learning to fly? I'd guess that over 50% of the flight PPL training is / should be learning the feel of the plane. Only when I started IFR training was it more procedural training. Being and getting that ATP is more about mastering procedures, but maintain that mastering that "feel" of those pulleys and cable driven flight control surfaces is ultimately one of the most important aspects of flight.

A little thread bump with an interesting article:
Loss of Control Tops NTSB 'Most Wanted' Safety List | Flying Magazine

What jumps out here: "What can be done to reduce the risk of loss of control for GA pilots? Installing safety gear such as an angle-of-attack indicator is a good first step, the Board said."

What it should read is "installing AOA indicator and training pilots on how to use it."

Thread bump, seems the FAA thinks AOA indicators on GA aircraft will help save lives.
FAA and GA Community Launch Fly Safe Campaign

Nah!

Don't you know it is much more fun to ridicule something that has been around and used for so long and is of GREAT assistance to controlled flight?

That dang old AOA is nothing but a magic 8 ball anyway. :D

never mind.

The beauty of AOA is that it's exceedingly simple. The systems for GA use take about 10 minutes of instruction to fully understand. They are also not usually vane type systems. Most for GA incorporate pressure sensors in the heated AOA probe or like in my aircraft differential pressure via two small holes in the wing.
Most GA systems also incorporate a aural warning. Mine simply says angle, angle push at about 5 knots above the 1 G stall. It however will always warn me before the aircraft stalls regardless of aircraft attitude or G loading. One of the interesting side effects of installing AOA is some very high time GA pilots realizing that they were very close to stall in the turn to final.
Where AOA really earns its keep is when things go wrong. It instantly lets you fly a best rate turn back to the airport without fear of a stall. It's going to warn you when a bug gets lodged in the pitot tube and your airspeed is way off. It's going to scream at you when you are turning final in heavy turbulance, just got a oil pressure warning and a aircraft announces he is at ¾ of a mile on a straight in at your position and you over bank and pull a bit to hard. AOA is the cheapest insurance you can't get against the number one cause of death in a GA aircraft.

I think that Avidyne actually uses AHRS for a derived AOA indication based on velocity vector and acceleration, offered as an upgrade. As far as I know there is no upgrade for the G1000.

I googled "AOA" and "religion" and found this link, which I agree with completely. Nice to see other non-crazy voices, but I'm sure he will be accused of witchcraft too! :rolleyes:

Angle of Attack isn't a miracle cure - Air Facts Journal

From the article:

Exactly what I have been saying.

AOA also could be a useful training tool, and would be reasonable in new constructions. However, the last thing we need in general aviation is more FAA regulation, championed by those who don't even understand current regulations.

Absolutely. Browsing NTSB reports will confirm this.

Found the Aspen device. Only $1995 for a software upgrade! That's aviation for you.

Aspen's AOA Software To Sell For $1,995 - AVweb flash Article

If by "religion" you mean the manner in which to perform your aircraft to its' maximum potential which may someday determine mission success or life and death - - then yes - it is a religion.

You don't **NEED** that fancy (insert your favorite flavor of glass cockpit either), but many are spending quite a bit of money to install them into every cockpit out there! It is just anohter tool.

Exactly, no one is saying it is the ONLY instrument, but combine airspeed and AOA, and a pilot can truly know how his aircraft is performing and where it is in the envelope.

And the author in the article calls it a "religion," proving his ignorance. Like USMCFLYR said, it is a religion--but only if being the best pilot you can be is important.

From my almost year now of flying 737s, I very much miss an AOA gauge, as the airspeed on final approach can vary from one flight to the next by 30 knots. Yes, we have indicators of how slow you can get, but an AOA (which the Captain has in his HUD, btw, so someone thought it was important!) would give me more SA.

Would it have prevented the Asiana 777 in SFO? Who knows, but it would have been one more indication that they might have caught to prevent getting so slow.

I see what you are saying, but I also don't agree.

The problem with airspeed as a proxy versus an actual AOA gauge is that it doesn't give you any information about load factor.

I have done low angle fixed wing stuff and aerobatics, and you can make due without an AOA IF you understand the relationships and are paying attention to the "feel" of the airplane. Of course, feel is subjective and even from one airplane to another, the warning indications may be different. I have flown fleets of older airplanes where the stall speeds could vary by +- 5 knots on the same exact airframe design.

The great thing about AOA is that not only does it give you a visual representation of what the wing is doing, but it is a fantastic tool to teach primary students the relationships they are supposed to understand in various regimes of flight. It is possible to do it without an AOA, but an AOA display really hammers it all home.

From a safety standpoint, it is a nice tool for backup guidance on the single most important performance aspect of an airplane at those time when you are distracted, maneuvering, looking or traffic, at the end of the day when performance is waning. Some airplane will have little to no warning approaching the stall in an uncoordinated banked turn, and by the time the pilot figures it out by "feel" it is too late.

If there was no benefit to these devices there simply wouldn't be any stall/spin accidents at low level (or any level for that matter) and loss of control wouldn't be a primary cause of GA accidents. The data on the need for these types of devices speaks for itself.

Good post, and I'm not saying much different. My load factor is approximately 1.0 on final approach. Accelerated stall delta is within the measurement error of the ASI.

I also agree. This is why Cirruses are so dangerous and have the stall/spin rates to back it up. We briefly discusse this in another thread. They have spring-loaded controls that push you toward neutral, which eliminates the "feel" of the plane. If they had airbus-style fully electronic fly-by-wire without force-feedback it would be a similar issue; Cirrus has actually installed a somewhat stick-pusher envelope protection on the latest models. I'd prefer to "be one with the plane" Yoda-style.

Not just fly, feel you must.

If you can ever back this up with well-designed study data I will be readily convinced, but I feel that adding yet ANOTHER instrument to look at "when you are distracted" is not a good idea, when you already have a great proxy for AOA. If he is pulling 3G's at that time without understanding what an accelerated stall is, then well, the pilot might have bigger problems, and likely wouldn't understand yet another idiot-gauge.

That statement is a logical fallacy.