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-   -   Not understanding AoA indicators... (https://www.airlinepilotforums.com/safety/84956-not-understanding-aoa-indicators.html)

F15Cricket 06-10-2015 01:44 PM

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

RhinoPherret 06-11-2015 03:38 AM


Originally Posted by F15Cricket (Post 1900960)
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

FXDX 06-11-2015 06:56 PM

never mind.

sailingfun 06-24-2015 08:11 AM


Originally Posted by cardiomd (Post 1764238)
The ones I've seen are still the mini-weathervane sticking out of the side of the plane that rotates with the relative wind. Vulnerable to freezing, so may need heater. Heater goes - gauge may stick. It could also be broken off or damaged. It is hard to ignore a noncovered invalid instrument and if that failure is subtle it may contribute to a chain of events instead of preventing it.

Nowdays everything is microcontrollers and digital instead of old systems, so I'd bet the electronics are very reliable.



Oh come on... If you did it unintentionally on a routine base to final turn then yes, you shouldn't be flying. I suspect it was not though, and more of an intentional maneuver or practice, and you know and appreciate the difference. ;)



I don't think you understand my position at all. I have zero experience with AOA gauge, and wouldn't retrofit my plane if it were zero cost. I'm a fan of it though with new planes and I personally would use it, but do not feel it is remotely needed for most GA pilot who doesn't go into the flight levels or pull high g maneuvers into near accelerated stalls at the edge of the performance envelope. The average pilot, who finds the G1000 exceedingly complex, would simply ignore it.

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 ĺ 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.

cardiomd 06-24-2015 05:45 PM


Originally Posted by sailingfun (Post 1914054)
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.

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:


Ex-military pilots (like some on the ICON team) love AoA because itís religion in the military. To them, it seems shocking that GA pilots are still flying based solely on airspeed. Iíll 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.


Airspeed control on final approach matters a lot more than a new instrument in the panel.

Hereís the simple fact that most AoA proponents know, but donít 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 youíre doing aerobatics or flying a jet at FL410, an AoA instrument may be essential; in the pattern in a 172 itís not going to tell you much more than the airspeed indicator.
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.


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 wonít help the idiot who buzzes his girlfriendís 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 ďloss of controlĒ heading.
Absolutely. Browsing NTSB reports will confirm this.

cardiomd 06-24-2015 05:46 PM

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

USMCFLYR 06-25-2015 02:44 AM

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.

F15Cricket 06-25-2015 11:02 AM


Originally Posted by USMCFLYR (Post 1914857)
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.

owequitit 06-29-2015 07:01 PM


Originally Posted by cardiomd (Post 1914577)
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.

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.

cardiomd 06-30-2015 01:41 PM


Originally Posted by owequitit (Post 1918311)
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.

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.


Originally Posted by owequitit (Post 1918311)
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.

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.


Originally Posted by owequitit (Post 1918311)
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 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.


Originally Posted by owequitit (Post 1918311)
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.

That statement is a logical fallacy.


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