AOA Indicators

[drgwentzel]

Flyers,

What is the group's opinion on AOA indicators in our airplanes? I am seeing the same old stance from some pilots that we have with any new device, "A real pilot doesn't need such a useless crutch." I have seen some real distaste for these devices. Did I miss something? Why all the hate about an instrument?

Did the FAA mandate these devices by 2020 in all aircraft, just like ADS-B?

If not, then if you don't want one, don't buy one. However, if someone feels they are the sprinkles that need to be on their ice-cream, then by all mean have at it.

This is the same argument that comes along with every new instrument. I remember hearing the ranting that any pilot that utilized a GPS was total wuss-bag and not even a real pilot and should dis-enroll him or her self from the club. After all, a real pilot only requires a map, a watch and a Nav-Log.

Someone questioned when one might need an angle of attack indicator. Well need is a strong word. For basic VFR flight, we don't need a vertical speed indicator, we don't need to turn and bank indicator, we don't need an attitude indicator and we don't need a Gyro stabilized heading indicator either. I think we will all admit they are nice to have.

They mentioned the use of the white line on airspeed indicator. As far as I know, the white line has nothing to do with an accelerated stall which is the most common stall to catch a pilot off guard. It's fast and abrupt and if it happens in uncoordinated flight, the plane can be upside-down one second after the stall horn offers it's first syllable of admonition.

An AOA indicator might come in quite handy with an engine failure on take-off where you can't land straight ahead and a turn back would save yours and your passenger's lives. The turn back might require a 60+ degree bank at slow speed and I for one would love the objective guidance of an AOA instrument at that moment.

If every flight was uneventful then we should rid ourselves of the excess weight of ELT's, CO detectors, life vests, fire extinguishers, smoke hoods, handheld radios, seat-belts, shoulder harnesses and the like.

I have a GPS along with every item mentioned above...and I might even buy an AOA indicator...I hope I can still call myself a pilot.

Sent from my iPad

 

[Velocity173]

Well we had an extensive discussion on this recently in two different threads. I agree, it can be a nice thing to have but I don't see it preventing any type of accident. I think it will allow a pilot to fly a more precise profile but that's about it. Pilot's have balled up aircraft for decades with a stall horn blaring in the background. Another "awareness device" isn't going to magically keep them from crashing.

 

[Dead Stick]

Well we had an extensive discussion on this recently in two different threads. I agree, it can be a nice thing to have but I don't see it preventing any type of accident. I think it will allow a pilot to fly a more precise profile but that's about it. Pilot's have balled up aircraft for decades with a stall horn blaring in the background. Another "awareness device" isn't going to magically keep them from crashing.

You sound so sure about this. Have you ever flown an airplane with an AOA indicator?

 

[Velocity173]

You sound so sure about this. Have you ever flown an airplane with an AOA indicator?

No, but is it magically going to take the controls away from me and prevent me from stalling the aircraft? Colgan 3407 had a stick shaker and the pilot fought it because he panicked. Asiana 214, one of the pilots stated several times "sink rate" and the Captain failed to take action. Plenty of other accidents where even professional pilots had adequate warning but they failed to take action. It's easy to look at accidents and distance ourselves and say it'll never happen to us but yet it still does.

It the DVD series that I recommended (Decision Making) there is a video with Dick Rutan taking off in a rocket Longeze. During take off there is a bright red light (temp) just blaring away at him. He was so preoccupied with the task of flying that he had no clue it was lit up. It gives an excellent insight to how the brain prioritizes and sometimes neglects secondary inputs outside of the primary task of flying. I've seen it happen many times instructing in the Army in peacetime and in combat. When pilots are in a high stress situation or they panic, you'd be amazed at what they neglect to see and hear.

I'm not saying to not go out and buy one. By all means, if you don't believe the 5-10 kts of warning a stall horn provides is sufficient, then buy one. Personally, I've done full aft stick accelerated stalls in my Glasair without any device and the buffet gave ample warning for recovery. To each his own.

 

[Dead Stick]

You sound so sure about this. Have you ever flown an airplane with an AOA indicator?

No, but...

You're dismissed, next witness please.

 

[Brad Z]

You sound so sure about this. Have you ever flown an airplane with an AOA indicator?

I haven't, but understanding the principle of critical angle of attack, I can see the benefit of such a device.

 

[Dead Stick]

I haven't, but understanding the principle of critical angle of attack, I can see the benefit of such a device.

You're dismissed as well, but I like you.

 

[Dead Stick]

It the DVD series that I recommended (Decision Making) there is a video with Dick Rutan taking off in a rocket Longeze...

Come on guys, we all know that if Dick had had any ADM skilz at all he would have never climbed into the Voyager with his girlfriend for that flight around the world. I don''t think they've spoken to each other since. Hmmm... maybe that's a good thing. Nevermind.

 

[bobmrg]

You sound so sure about this. Have you ever flown an airplane with an AOA indicator?

I have, and so has Cap'n Ron (among many others). An airspeed indicator is a proxy for angle of attack, and not a very good one.

The FAA has not dictated their use, simply made it easier for airplane owners to have one installed.

Bob Gardner

 

[murphey]

You sound so sure about this. Have you ever flown an airplane with an AOA indicator?

I have, and so have many who fly LSAs & experimentals. A number of the LSAs have an AOA as standard or optional equipment, the Remos for example. And don't forget that most (if not all) military tactical aircraft have them installed.

 

[bnt83]

Both airplanes the family has owned came with an AOA, there's no distracting dial to watch, just honks an audible tone when getting close to stall.



IIRC all the airplanes I've flown have them.

Never felt I NEEDED anything else...

 

[Lindberg]

I've never flown a plane with such an indicator, so other than how they function, how is an AOA indicator better or different than a stall horn?

 

[Fearless Tower]

Flyers,



What is the group's opinion on AOA indicators in our airplanes? I am seeing the same old stance from some pilots that we have with any new device, "A real pilot doesn't need such a useless crutch." I have seen some real distaste for these devices. Did I miss something? Why all the hate about an instrument?

FWIW, I have observed that much of the disdain is aimed at a few AoA proponents that believe that the FAA should mandate installation of AoAs in all aircraft, vice make it easier for people to install them.

 

[bnt83]

I've never flown a plane with such an indicator, so other than how they function, how is an AOA indicator better or different than a stall horn?

When does a stall horn "SOUND"? When nearing the critical angle of attack, right?

A stall warning horn IS a basic AOA...

 

[ja_user]

I've never flown a plane with such an indicator, so other than how they function, how is an AOA indicator better or different than a stall horn?

A stall horn alerts you of a defined AOA point, in an On/Off fashion.
A AOA indicator simply gives you more detail over a larger range than.

I equate it to an "Engine Tempature" light, versus a temperature gauge. Both can tell you something close to the same thing, during a narrow field of operation. The Gauge gives you better information through a wider range of operation.

 

[Henning]

When the time comes to stuff the plane into some hole with a 50/50 shot on live or die and things don't look particularly good, the AOA will call your excess energy for your current weight and conditions a whole lot closer than airspeed. There are a couple of advantages to having an AOA, I can't think of a disadvantage to having one. The more accurate the information you rely on, the better off you are.

 

[FORANE]

I have one in the RV. It is kind of cute to look at occasionally. I personally do not see much utility of it and rarely find myself thinking I should look at the AOA indicator for useful information. Honestly, I have considered removing it to free up some panel space.
Am I dismissed also?

 

[Henning]

When does a stall horn "SOUND"? When nearing the critical angle of attack, right?

A stall warning horn IS a basic AOA...

Sure, but it's an on/off AOA, and then there is the calibration issue, where does it come on? On both a DA-20&40 I used to fly if I didn't tape off the horn hole correctly, the factory hole would give me a stall horn at 12kts over, that has it screaming at you the whole way down final if you're at a good landing speed. If you stay out of the stall horn until the flare, you float way down the runway unless you hardslip in over the numbers, both are very annoying.

 

[Dead Stick]

I have one in the RV...

Dismissed.

 

[Dead Stick]

When the time comes to stuff the plane into some hole with a 50/50 shot on live or die and things don't look particularly good, the AOA will call your excess energy for your current weight and conditions a whole lot closer than airspeed. There are a couple of advantages to having an AOA, I can't think of a disadvantage to having one. The more accurate the information you rely on, the better off you are.

This is the best "long story short" answer so far. Here's a video that has a pretty good explanation...

http://www.iconaircraft.com/video-icon-aircraft-a5-angle-of-attack.html

Also having AOA comes in handy for more than figuring out what 1.3 Vso happens to be. Having an AOA indicator has no downside. The only thing is that it really needs to be up on the glareshield where it can be glanced at while looking out the windshield.

 

[bnt83]

Having an AOA indicator has no downside.

Other than:

#1 Another distraction
#2 Could take up panel space
#3 Add weight
#4 Add more complexity and more stuff to break
#5 Add maintenance cost


I'd rather put the money in the gas tank and go practice slow flight on the way to a $100 burger.

 

[bobmrg]

A conventional airspeed indicator relies on the pressure exerted by the relative wind at the entrance to the pitot tube. In level flight, with the relative wind parallel to the airplane's longitudinal axis, it is pretty much a one-to-one thing. When it comes time to land, with the deck angle varying from level to nose down to nose up (depending on a lot of factors), the relative wind blows across the pitot at an angle, not directly into it. That's why we see airspeed correction tables in Section 5 of flight manuals/POHs. The accuracy of an AOA is not affected by deck angle.

Bob Gardner

 

[Marauder]

I've never flown a plane with such an indicator, so other than how they function, how is an AOA indicator better or different than a stall horn?

Stall speed changes at different weights. An AOA indicator provides a better indication of stall speed based on weight. Some of the arguments against using them for light airplanes suggest that VSo at different landing weights & CG loadings results in only a few knots difference.

Personally, I am having one installed.

 

[Everskyward]

You sound so sure about this. Have you ever flown an airplane with an AOA indicator?

I have, and all of the airplanes have had some kind of cautionary verbiage about not using it as a primary instrument.

 

[Dead Stick]

Other than:

#1 Another distraction
#2 Could take up panel space
#3 Add weight
#4 Add more complexity and more stuff to break
#5 Add maintenance cost


I'd rather put the money in the gas tank and go practice slow flight on the way to a $100 burger.

#1 Who stares at an AOA indicator? That's not where your eyes whould be when you're flying.
#2 It should be mounted on the glairshield.
#3 If you take a dump before going to the airport you'll more than make up for the additional weight.
#4 It's probably one of the simplest, most reliable, systems on the entire airplane.
#5 Negligible at best.

Like I said, there is really no down side. In the case of an AoA system the pluses way outweigh the minuses.

 

[Dead Stick]

I have, and all of the airplanes have had some kind of cautionary verbiage about not using it as a primary instrument.

I've got close to 13,000 hours in AoA equipped aircraft and you are correct. Who here has advocated that they were to be used as a primary flight instrument?

 

[brcase]

Other than:

#1 Another distraction
#2 Could take up panel space
#3 Add weight
#4 Add more complexity and more stuff to break
#5 Add maintenance cost


I'd rather put the money in the gas tank and go practice slow flight on the way to a $100 burger.

You missed the main one, and the most of the arguments against them infer this one.

It is installed thinking it is a safety device, when it really is a performance/information device. The down side is that those installing it thinking it will improve safety don't really understand what causes most stall spin accidents.

While I am sure there a few exceptions, very few modern pilots that have stalled and crashed were looking at the airspeed indicator and actively listening for the stall horn, ready to recover. They wouldn't have been looking at a AOA indicator either.

AOA indicators can be a great performance indicator, but it isn't a better stall warning device than a stall warning is.

I liked the Gauge vs Warning light analogy, the Gauge gives you much more information but is less likely to alert you to a problem than a light. Ideal situation is both.

Brian

 

[Everskyward]

I've got close to 13,000 hours in AoA equipped aircraft and you are correct. Who here has advocated that they were to be used as a primary flight instrument?

The OP?

An AOA indicator might come in quite handy with an engine failure on take-off where you can't land straight ahead and a turn back would save yours and your passenger's lives. The turn back might require a 60+ degree bank at slow speed and I for one would love the objective guidance of an AOA instrument at that moment.

 

[bobmrg]

A conventional airspeed indicator relies on the pressure exerted by the relative wind at the entrance to the pitot tube. In level flight, with the relative wind parallel to the airplane's longitudinal axis, it is pretty much a one-to-one thing. When it comes time to land, with the deck angle varying from level to nose down to nose up (depending on a lot of factors), the relative wind blows across the pitot at an angle, not directly into it. That's why we see airspeed correction tables in Section 5 of flight manuals/POHs. The accuracy of an AOA is not affected by deck angle.

Bob Gardner

 

[Dead Stick]

The OP?

An AoA makes a great backup to an ASI. Over the years I've had several ASI failures and if you've got an AoA system on board, it's a total non-event, even in a transport category jet. As far as other uses besides stall avoidance - there are many other things which are predicated upon AoA but which we use airspeed as a poor substitute. If you've got the system, learn what it can tell you about what the wing is doing. It's good for much more than simple stall avoidance.

 

[Everskyward]

An AoA makes a great backup to an ASI. Over the years I've had several ASI failures and if you've got an AoA system on board, it's a total non-event, even in a transport category jet.

You have lost both ASIs and the backup?

As far as other uses besides stall avoidance - there are many other things which are predicated upon AoA but which we use airspeed as a poor substitute. If you've got the system, learn what it can tell you about what the wing is doing. It's good for much more than simple stall avoidance.

I never said they weren't useful to a certain extent. However I agree with the other poster here in that they are being pushed as another safety panacea. If you are going to have a stall/spin accident without an AOA you probably are going to have the same accident even with one.

 

[Dead Stick]

You have lost both ASIs and the backup?

I never said they weren't useful to a certain extent. However I agree with the other poster here in that they are being pushed as another safety panacea. If you are going to have a stall/spin accident without an AOA you probably are going to have the same accident even with one.

Not all 3 in jet aircraft, not at the same time, stuff like that only happens in the in the sim. That's one of those events that would be measured in terms of geologic time. When we've practiced in the sim it doesn't even merit a mention - it's a total non-event. In your typical light aircraft, it would be much different and something that would be of concern to many less experienced pilots. Having an AoA completely eliminates all of the angst that would be associated with the loss of an ASI.

As for your second statement, I disagree with that. It's just another tool, not a panacea. It's like having airborne weather radar, a sferics detector and XM weather. They all - more or less - tell you the same thing, but they are actually 3 distinct tools with 3 distinct uses and 3 distinct sets of limitations. I still want all three of them if I can.

However, time will tell. I guess there have been aircraft lost due to fuel starvation that were equipped with GPS integrated fuel totalizers. When it comes to doing stupid things in airplanes, we have always managed to find a way in spite of everything. :wink2:

 

[Henning]

I never said they weren't useful to a certain extent. However I agree with the other poster here in that they are being pushed as another safety panacea. If you are going to have a stall/spin accident without an AOA you probably are going to have the same accident even with one.

There is nothing that would provide aviation a safety panacea, and I agree it's wrong to market them in such a fashion, I also agree that the person who is going to have a stall spin will have it with or without. Without a stick pusher, the AoA is not a safety device, it just provides information. A good pilot with an understanding of the information displayed can achieve a higher level of safety in critical situations by being provided the most accurate reserve lift information available to them. Even in a transport jet it can be used to cross check the Vref speed card or speed bug information and can also provide some information about the correct deployment of flaps and gear. If speed and AoA aren't synching up where they should be, there is a problem somewhere.

 

[Henning]

Not all 3 in jet aircraft, not at the same time, stuff like that only happens in the in the sim. That's one of those events that would be measured in terms of geologic time. When we've practiced in the sim it doesn't even merit a mention - it's a total non-event. In your typical light aircraft, it would be much different and something that would be of concern to many less experienced pilots. Having an AoA completely eliminates all of the angst that would be associated with the loss of an ASI.

As for your second statement, I disagree with that. It's just another tool, not a panacea. It's like having airborne weather radar, a sferics detector and XM weather. They all - more or less - tell you the same thing, but they are actually 3 distinct tools with 3 distinct uses and 3 distinct sets of limitations. I still want all three of them if I can.

However, time will tell. I guess there have been aircraft lost due to fuel starvation that were equipped with GPS integrated fuel totalizers. When it comes to doing stupid things in airplanes, we have always managed to find a way in spite of everything. :wink2:

Meh, loss of an ASI even in a small plane with one is pretty much a non event.

 

[Everskyward]

Not all 3 in jet aircraft, not at the same time, stuff like that only happens in the in the sim.

Yeah, that's why I asked. I have lost the ASI in a jet, right after rotation. I looked at the backup, then at the one on the right side, then did the reversion putting the display from the right side on the left. It turned out to be the left ADC.

As for your second statement, I disagree with that. It's just another tool, not a panacea.

I never said it wasn't just another tool. I said that I thought it was being promoted as a panacea in some circles.

 

[Everskyward]

Meh, loss of an ASI even in a small plane with one is pretty much a non event.

Right. My CFI covered the ASI an made me fly a pattern without one before I even got my private.

 

[Dead Stick]

Right. My CFI covered the ASI an made me fly a pattern without one before I even got my private.

It's a something that every pilot should be comfortable doing. I've given enough BFRs and ICCs over the past 40 years to know that not everyone is.

 

[Ted]

We installed in Alpha Systems AoA in the 310 at last annual. I like it quite a bit. I've found it's helped make my short field landings more consistent (especially since I'll have short field landings with varying loads which have varying optimal speeds) and I like the verbal warning it gives when getting too slow. I think the latter is a good safety feature.

Lots of people say a real pilot doesn't need an AoA. I'd agree it's not necessary, but I like having it and I think it's a good safety feature. And since I landed and took off the 310 from a 1900x25 strip without it, I guess that makes me a real pilot, so that's good enough.

 

[RhinoDrvr]

I've got close to 13,000 hours in AoA equipped aircraft and you are correct. Who here has advocated that they were to be used as a primary flight instrument?

The US Navy? We use AOA as primary energy indication during the entire approach/landing phase at the field and at the boat, VMC and IMC. Much more precise than airspeed. More useful also.

Max range, max endurance, max performance, approach speed etc... can be set off AOA which won't vary with weight. Perhaps most useful it really allows you to max perform the airplane if required.

 

[Dead Stick]

...We use AOA as primary energy indication during the entire approach/landing phase at the field and at the boat, VMC and IMC. Much more precise than airspeed. More useful also.

Max range, max endurance, max performance, approach speed etc... can be set off AOA which won't vary with weight. Perhaps most useful it really allows you to max perform the airplane if required.

There you have it... the true value and utility of AoA. (I was wondering how long it would take for someone else who understands would chime in.) It's good for so much more than stall avoidance - if you take the time to learn how to properly use it. When you're operating out near the edges of the performance envelope it literally takes all of the guess work out of it. The FAA is finally getting on the bandwagon and making it easier to install them on Part 23 GA aircraft. It's about time. As they said in that video, they are a game changer - but only if you're willing to take the time and are willing to learn something new.