AoA indexer system?

[Nick - A2A]

As an instructor however I see a potential issue that these indicators might be relied on as a PRINCIPAL INDICATOR for stall with instructors placing emphasis on using them at the expense of much needed and in my opinion absolutely necessary instruction and exposure to stall recognition by feel, sound, and visual cues that are an imperative part of the basic flying skill set.

Point well taken, but I reckon we could use a similar argument against stall horns being fitted in aircraft. Aren't these modern AoA warning systems effectively just a 21st century development of a stall horn? Not something to be used (or instructed) as the primary indicator for stall, but something which might save a few lives anyway.

I do wonder how much an AoA indexer could help, if at all, with the classic skidded base to final turn into a spin? I get the impression that it would be near useless in this scenario.

That's an interesting point. Presumably that's why the convention is to fit the stall warning vane to the left wing, as for a standard left hand traffic pattern this would be the one with the higher AoA in that dangerous skidded base to final turn scenario if I understand correctly. I assume AoA sensors would be retrofitted to the left wing too, but presumably if flying a right hand traffic pattern, such an installation may be a less effective 'early attention getter' in this skidded turn scenario?

Nick

[Oracle427]

Well it just so happens that I've practiced this scenario in both an N and S model 172 and in both cases, the stall horn never went off, either turning to the right or left. Maybe we entered the stall a little too aggressively? Either way, it is frightening to see how you have no time and no chance of recovery if that happened in an actual pattern. Totally on board with Dudley, that there are dozens of visual and sensation cues screaming at you that something is wrong, if you have been properly trained and remain proficient enough to listen to them.

When I did this I went from a very badly executed skidded turn into rolling into the turn upside down and then entering a spin. The stall horn starts to make all sorts of odd noises as all that happens but by then it is too late. I figured the AoA indicator would face the same issue with the warning being given too late.

[Nick - A2A]

My feeling is that the AoA indexer would have the advantage over the traditional stall warning system in this scenario, in that it gives the pilot that visual confirmation that he or she is flying and turning at a safe AoA (i.e. a good margin above the stall), rather than it being a stall detector as such.

I understand that departure into a stall will happen real fast in the case you're describing Oracle, but presumably only once you've allowed airspeed to decay and AoA to rise?

Sorry guys: feel like I've ventured into territory I'm ill-equipped to discuss, but you have to put up with a few flight simmers round here!

Cheers,
Nick

[Oracle427]

Well as Dudley noted, AoA is AoA irrespective of airspeed. I guess it's the accelerated nature of the event with the aircraft yawing, the wings loaded up to maintain altitude and the higher bank angle with a smidge of outside aileron thrown in.

I know how the AoA horn works and how it is able to fairly directly sense the AoA. I'm not sure how the indexer works and how it feels the AoA. Unless it has some sort of external sensor, I'm guessing it uses airspeed, bank angle and other data to compute the AoA based on some algorithm.

[DHenriques_]

As an instructor however I see a potential issue that these indicators might be relied on as a PRINCIPAL INDICATOR for stall with instructors placing emphasis on using them at the expense of much needed and in my opinion absolutely necessary instruction and exposure to stall recognition by feel, sound, and visual cues that are an imperative part of the basic flying skill set.

Point well taken, but I reckon we could use a similar argument against stall horns being fitted in aircraft. Aren't these modern AoA warning systems effectively just a 21st century development of a stall horn? Not something to be used (or instructed) as the primary indicator for stall, but something which might save a few lives anyway.
Nick

I have never taught stall with other than a passing reference to the stall horn. After noting to a student the way the FAA wants the horn to be used during a flight test and seeing to it that the student knew and understood that I immediately stopped referencing the horn as well as weaning the student away from the 1g stall which is virtually useless and not where the stall situations occur in flight that pose problems. THAT happens in the accelerated stall range and THAT was where I taught stall to all my students.
The 1g stall and its relationship to the ASI only happens at GW and is seldom where you want your awareness of stall to be focused in flight. The ONLY positive reference that equates to stall is angle of attack. Knowing this and understanding it one might start to believe that an indicator that warns of high AOA would be quite useful and it could be, but NOT at the expense of solid training in physical and visual stall warning cues. THAT is where solid instruction saves lives.
Dudley Henriques

[Nick - A2A]

I'm not sure how the indexer works and how it feels the AoA. Unless it has some sort of external sensor, I'm guessing it uses airspeed, bank angle and other data to compute the AoA based on some algorithm.

The retrofit devices that I was looking at (those from Alpha Systems and Garmin) seem to be completely standalone systems with their own AoA sensor which is mounted to the underside of the wing. No integration with the existing avionics at all.

The ONLY positive reference that equates to stall is angle of attack. Knowing this and understanding it one might start to believe that an indicator that warns of high AOA would be quite useful and it could be, but NOT at the expense of solid training in physical and visual stall warning cues. THAT is where solid instruction saves lives.

100% agreed, sim-pilot though I may be!

Nick

[Oracle427]

Totally going off topic here, but I have to say that when I started my flight training I thought my instructor was too chatty, was wasting time and therefore money and repeating lessons with subtle changes that I was too green to comprehend.

Over time I got to know him well and put my trust in him. I still keep learning about what he shared with me to this day when I reflect on those lessons. While he did have to teach to the curriculum mandated by the FAA so that I could pass a checkride, he also made damn sure to spend all that extra time to make sure that I understood much more through actual practice. He didn't teach disrespect or diregard for the FAA standards, not at all. But he went beyond to make sure I was well armed in ways I probably still don't fully appreciate. I wish he still lived in the area...

[DHenriques_]

Totally going off topic here, but I have to say that when I started my flight training I thought my instructor was too chatty, was wasting time and therefore money and repeating lessons with subtle changes that I was too green to comprehend.

Over time I got to know him well and put my trust in him. I still keep learning about what he shared with me to this day when I reflect on those lessons. While he did have to teach to the curriculum mandated by the FAA so that I could pass a check ride, he also made damn sure to spend all that extra time to make sure that I understood much more through actual practice. He didn't teach disrespect or disregard for the FAA standards, not at all. But he went beyond to make sure I was well armed in ways I probably still don't fully appreciate. I wish he still lived in the area...

Exactly! My kind of CFI.
DH