ATR-72 crash at PKR, Nepal. Many fatalities feared.

[Gabriel]

An accelerated stall ... ex: When you increase the load factor by 1.4 by banking 45 degrees at constant power setting while applying backpressure to preserve altitude.

Which would increase your stall speed by about 18%

The absolute minimum maneuver speed (not to be used on approach) is VmLB (VmLB is 1.18 the 1G stall speed at flaps 0) and the bank limit is 15deg at that speed.

Great, so you would be at the verge of the stall if you did a 45-bank, altitude preserving turn at this absolute minimum maneuver speed that is already below the absolute minimum approach speed.

How much do you think they banked before losing control?

[Gabriel]

Do you feel that certain about when the stall occurs or what part of that roll is uncommanded?

Once the wing drops steeply (fully stalled)I don't see how this was recoverable at that low altitude. There is not altitude left to trade.

Certain is a strong word. More like very confident.
After the plane fully stalled (i.e. after it went 1 degree past the critical AoA) and after the wing STARTED to drop uncommanded, you can still recover with minimum loss of altitude.
CAN... The question is WILL? The plane will, if acted upen effectively.
The problem is... the pilot that without realizing it let the situation develop into this mess, is unlikely to have what it takes to get out of it.

[3WE]

the pilot that without realizing it let the situation develop into this mess

Just for perspective, it was only a couple of seconds between the pull up (an ass-umed short stall warning) and the establishment of a significant, wing-dropping, momentum-building descent…little chance for recovery, even for ITS.

IMO the bad piloting was [speculation] allowing speed decay to our hypothesized “just above stall” and perhaps leading with a pull up instead of palm oil…Those need to coordinated with a bit of skill.

PS: You could acknowledge my accelerated stall comment.

[Gabriel]

Just for perspective, it was only a couple of seconds between the pull up (an ass-umed short stall warning) and the establishment of a significant, wing-dropping, momentum-building descent…little chance for recovery, even for ITS.

I disagree. If 1 second after the SW / stall / start of wing drop (assuming they were more or loess simultaneous) they had reduced the AoA a bit, the stall would be over, the roll would stop almost on its tracks, and normal aileron authority would be recovered, letting you level the wings. The altitude loss would go almost exclusively to managing pitch and airspeed to avoid a secondary stall after the initial recovery, and since they were barely at the edge of the 1G stall speed that would not have taken much.

Again, I am very confident that this was technically doable. I am little confident that these pilots could have pulled it (pun not intended)

IMO the bad piloting was [speculation] allowing speed decay to our hypothesized “just above stall” and perhaps leading with a pull up instead of palm oil…Those need to coordinated with a bit of skill.

No matter what was the situation, turn or no turn, go around or not, 0, 1 or 2 engines failure, whatever, they definitively let it slow down way too much and then made it worse by pulling up. And I am being pretty black-and-white on that.

PS: You could acknowledge my accelerated stall comment.

Your comment is acknowledged. I don't really disagree with it. Or agree. It is mostly semantics. For me stall is 90% about angle of attack. Speed, load factor, bank angle, etc are in a far second place. You stall when the AoA reaches the critical AoA and that happens when you move the elevator that many inches back, at whatever speed, load factor, bank angle. The problem is when you get into a situation where you want (bank, load factor) or need (speed) more lift that the wing can give. Which is not dissimilar to what you said in the previous paragraph.

[3WE]

I disagree. If 1 second after the SW / stall / start of wing drop…

We will never know, BUT, yes

I would bet a beer that YOU would recover.

I would also bet a beer that I wouldn’t get a stall warning.

I’d even bet a beer that if YOU stalled it and then said “your plane” to me (just to be a Richard), I’d recover…unless there was a hot woman in a bikini in a hang glider out of my window.

But, it would very quickly get to where you could recover but be too low to avoid the ground, and there’s some arm-chair arrogance that THEY should have recovered.

My accelerated stall definition is important because it becomes a factor when you steepen the turn AND pull up on short final EVEN THOUGH YOUR AIRSPEED IS “ROBUST”. Conversely, a 1.25 G go-around should be a non-issue.

PS: Many planes lack AOA indicators

[Evan]

I disagree. If 1 second after the SW / stall / start of wing drop (assuming they were more or loess simultaneous) they had reduced the AoA a bit...

You mean give up altitude, descend? When they are about two wingspans above the trees, sideways, in a non-aerobatic ATR-72? You know that's unlikely to happen. Human nature won't allow it. I think you sometimes forget about psychology and instinct. The only way to prevent this kind of crash is to never let it get this far.

Great, so you would be at the verge of the stall if you did a 45-bank, altitude preserving turn at this absolute minimum maneuver speed that is already below the absolute minimum approach speed.

And what if you had fallen below that absolute minimum maneuver speed? And remember to factor in the pull-up before the maneuver. I keep having to remind you that error is a key part of this scenario.

How much do you think they banked before losing control?

I think the correction to the 12 centerline would require them to bank anywhere from 20 to 45 degrees, but that's just a guess. I don't think they were turning 2G's but perhaps 1.5G's. I guess the best answer is: too much.

[Evan]

I would bet a beer...

I bet you a beer Gabriel would have just continued for a nice stabilized precision approach to 30, even if it meant dealing with a bit of tailwind. And I mean that as a compliment.

[3WE]

I bet you a beer Gabriel would have just continued for a nice stabilized precision approach to 30, even if it meant dealing with a bit of tailwind. And I mean that as a compliment.

Oooo, good one. Do you have any documents recommending that planes not_land on 12? Airport notes, operating manuals?

This is a funner bet, but given the LLLLOOOONNNNGGGG list of accidents from
tailwind landings, fundamental rules AND his love of flying and maneuvering airplanes and making landings, and riding bicycles and being a good stall avoider, I’ll bet on him landing on 12.

Bank angles will remain under 30 degrees.

Edit: Confirmed

Unless some really specific concerns limited safety, Gabriel is landing into the wind. And I mean that as a compliment.

Making turns in an airplane to land into the wind, is not a specific concern. I mean that as a very broad statement.

When do I get my beer?

[3WE]

I think the correction to the 12 centerline would require them to bank anywhere from 20 to 45 degrees, but that's just a guess. I don't think they were turning 2G's but perhaps 1.5G's. I guess the best answer is: too much.

Fascinating information.

They downloaded the Evan Bizarre Alternate Imaginary Reality Recorder?

I know you said “guess”, but again, the non-existent steep bank is suggested.

[Evan]

Oooo, good one. Do you have any documents recommending that planes not_land on 12? Airport notes, operating manuals?

A local airport official stated that either runway was available. Still no METAR info, which is strange.

[Gabriel]

You mean give up altitude, descend?

Well, if you don't, you give up altitude and descend, but much quicker and steeper, and possibly inverted.

Human nature won't allow it.

Wrong. There are counterexamples.

I think you sometimes forget about psychology and instinct.

I don't. Instinct is designable.

The only way to prevent this kind of crash is to never let it get this far.

Agreed. Maybe not the ONLY but certainly the most reliable, effective, and sensible.

And what if you had fallen below that absolute minimum maneuver speed? And remember to factor in the pull-up before the maneuver. I keep having to remind you that error is a key part of this scenario.

No, of curse that error is a key part. But you seem to think that overbanking was part of the error. It wasn't.

I think the correction to the 12 centerline would require -

Irrelevant. The question was not abut requirement but about actuality. How much do you think they banked intentionally before losing control?

I don't think they were turning 2G's but perhaps 1.5G's. I guess the best answer is: too much.

No. Definitively no. 1.5Gs is more than 45 degrees. And I don't think that the problem was too much bank at all. It was CLEARLY too slow and perhaps a little bit of not-turn-related pull up.

I bet you a beer Gabriel would have just continued for a nice stabilized precision approach to 30, even if it meant dealing with a bit of tailwind.

And why would I do that if I can make a nice visual approach to RWY 12, land with a headwind, and still doing a stabilized approach (even if it includes a base-to-final turn)?

[3WE]

And why would I do that if I can make a nice visual approach to RWY 12, land with a headwind, and still doing a stabilized approach (even if it includes a base-to-final turn)?

Is Evan trolling?

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[Evan]

And why would I do that if I can make a nice visual approach to RWY 12, land with a headwind, and still doing a stabilized approach (even if it includes a base-to-final turn to a one mile final)?

Because it’s safer. Why? Because it’s stabilized and configured much earlier and there is less opportunity for error and more tolerance for error. Because there is higher workload. Because you’ve had zero experience flying the 12 approach that requires accurately timed and placed maneuvers at critically low altitude with very little margin for error. Because, even a crack pilot like yourself can make mistakes. And because you are fully capable of dealing with a slight tailwind.

And because there are the lives of 70 passengers in your hands.

[Evan]

Is Evan trolling?

Ha! That’s like Trump asking if Evan’s lying,

Since page 3:

It seems to me that they had to tighten the bank as they came around but not so steeply as I imagined.

Or they botched the go-around. But then why no evidence of stall avoidance response and why an immediate wing drop stall?

[3WE]

A local airport official stated that either runway was available.

Hmmmm.