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PIA A320 Crash Karachi

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PIA A320 Crash Karachi

Old 7th Jul 2020, 20:11
  #1581 (permalink)  
 
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Is there not a third option for (2) along the lines of: did they actually think the gear was down for the landing(*) and then "raised" it (but actually lowered it - continuing previous apparent state of confusion on this) to extend the glide when they realized they had no engines.

(*) thinking it's maybe possible they went around having, belatedly, realized they were too fast and brakes / reversers weren't kicking in, but not actually realizing they had landed gear-up.
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Old 7th Jul 2020, 20:44
  #1582 (permalink)  
 
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Originally Posted by Escape Path View Post
It would/will be very interesting to see how they managed the dual engine failure, after all the mess that happened right before...
Well given how they acted in a normal situation, do you really want to imagine their response to a non-normal situation?
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Old 8th Jul 2020, 11:22
  #1583 (permalink)  
 
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Originally Posted by Joejosh999 View Post
My question is 1) when did they realize they had dual engine failure and 2) had they already put the gear back down the final time? Or did they somehow know they had no engines YET put gear down anyway, not realizing it would kill their glide range?
RIP all.
Again we will have to wait for the full report.

From the videos of the final moments, it looked to me as if he was trying to find alpha max, but the protections were gone with the gear extension.
Despite all the cock-ups, it does appear that they were tantalising close to making the undershoot area, and perhaps walking away.

Just another marker in a sad catalogue of failures.

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Old 8th Jul 2020, 16:58
  #1584 (permalink)  
 
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Originally Posted by Check Airman View Post
Well given how they acted in a normal situation, do you really want to imagine their response to a non-normal situation?
From a pure accident investigation point of view, particularly of the human performance, I’d be really interested to know what happened after the go around. But my guess, also stemming from what we know that happened before the ahem, “landing”, is that it most likely was absolute chaos. Few things produce as much sensory overload as an A320 losing all power (both engine AND electrical) and getting into emergency electrical configuration. Not to mention the fact that it was stacking up over what was already quite a messy approach and... “landing”

As vilas pointed out, whether they started the APU or not, little was going to change their fortunes; a handful of electrical things spurring back into life (in daylight VMC), but no engines and no change in flight control laws (it would remain in direct law if my knowledge doesn’t fail me) wasn’t really going to help them that much. The gear down, ironically, is what drove the final nail in the coffin
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Old 8th Jul 2020, 18:58
  #1585 (permalink)  
 
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What kind of performance loss with gear down during landing approach?

Would you expect an undershoot of a mile or so? with no thrust available
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Old 8th Jul 2020, 20:11
  #1586 (permalink)  
 
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Never having tried it, I can’t speak from experience, but the second attempt was the one that would have benefited from the gear being up. The gear works better than the speed brakes in the 320. If I’m not mistaken, they crashed about a mile from the runway.

With the absence of the FDR data, we probably won’t know exactly when they lowered the gear, but I’m guessing if they’d waited until ~200ft to drop it, they may have walked away.

That of course assumes the windmilling engines would produce sufficient pressure to lower the gear and support the flight controls. That procedure would take a bit of planning and thought, which in fairness, even on a good day, would probably be difficult under the circumstances.

In my opinion, starting the APU would definitely have helped.
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Old 8th Jul 2020, 22:10
  #1587 (permalink)  
 
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Originally Posted by parkfell View Post
Can someone enlighten me as to whether the Insurers are likely to pay out given what has all the hallmarks of grave Gross Misconduct by the crew.
Add to that, the issue of whether any evidence is uncovered as to whether the licences were issued “fair and square”, and their continuing validity iaw licensing regulations.
Simply asking the question. I have no information one way or the other.
This is a very significant consideration. In at least a couple of my airline contracts, there seemed to be an involvement of national government in the insurance cover. For a national airline, that seems to be a conflict of interest, even with re-insurance. If an insurer had an opportunity to escape payment, it seems that that it would do so. If the airline was sufficiently negligent, like habitually allowing beaches of SOPs that would have prevented the accident, there might be a question mark over claims. If the airline did not know of breaches, but should have known, same question mark.
A friend of mine was a pax in an A320 accident at Bahrain. Religious considerations meant his wife did not get any compensation, but his closest male relative did and did not share it with the wife.
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Old 9th Jul 2020, 03:57
  #1588 (permalink)  
 
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In my opinion, starting the APU would definitely have helped.
Am I missing something? APU gets you out of ELEC EMER that brings CM2 instruments, it can take over pressurization, main use is starter assisted relight which wasn't going to happen. None of this would change PK8303 fate. Sully started APU from memory as good airmanship to get an engine going but once that didn't happen he also got no other help from APU. It doesn't get you out of G+Y. In PK8303 once they lowered the gear they were done in. Even if they could raise it they would've lost more height.
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Old 9th Jul 2020, 07:28
  #1589 (permalink)  
 
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Can someone enlighten me as to whether the Insurers are likely to pay out given what has all the hallmarks of grave Gross Misconduct by the crew.
I am not an expert, but I think it's almost certain that the insurance company will pay out. Typically an insurance company can't refuse their liability to a third party, but they can seek to recover that from the insured in the event that negligence is the cause.

If an insurance company (actually, the underwriter whether that's a name, another insurance company, or the Government as last resort) is unhappy with the potential risk then it's their problem and their responsibility to either ensure the problem is fixed or deny cover in the first place, at which point the airline wouldn't fly.
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Old 9th Jul 2020, 07:57
  #1590 (permalink)  
 
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Originally Posted by Teddy Robinson View Post
Again we will have to wait for the full report.

From the videos of the final moments, it looked to me as if he was trying to find alpha max, but the protections were gone with the gear extension.
Despite all the cock-ups, it does appear that they were tantalising close to making the undershoot area, and perhaps walking away.

Just another marker in a sad catalogue of failures.
The ALPHA PROT was long gone after the engines failed.
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Old 9th Jul 2020, 08:22
  #1591 (permalink)  

Only half a speed-brake
 
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@vilas I am away from the books. Does APU elec supply restore ALT law with AoA protection? That is for the Hudson (gear up) case.

Sully is a short-hand for "the crew of US Airways 1549", I suppose. 😉
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Old 9th Jul 2020, 10:06
  #1592 (permalink)  
 
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ELEC EMER itself is in alternate law with reduced protections. With dual Engine flame out APU doesn't restore anything except AC Bus2. Even AC essential bus remains locked with emergency generator.
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Old 9th Jul 2020, 11:11
  #1593 (permalink)  
 
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Originally Posted by vilas View Post
Am I missing something? APU gets you out of ELEC EMER that brings CM2 instruments, it can take over pressurization, main use is starter assisted relight which wasn't going to happen. None of this would change PK8303 fate. Sully started APU from memory as good airmanship to get an engine going but once that didn't happen he also got no other help from APU. It doesn't get you out of G+Y. In PK8303 once they lowered the gear they were done in. Even if they could raise it they would've lost more height.
From the Flight 1549 accident report:

Starting the APU early in the accident sequence proved to be critical because it improved the outcome of the ditching by ensuring that electrical power was available to the airplane. Further, if the captain had not started the APU, the airplane would not have remained in normal law mode.
[...]
The NTSB concludes that, despite being unable to complete the Engine Dual Failure checklist, the captain started the APU, which improved the outcome of the ditching by ensuring that a primary source of electrical power was available to the airplane and that the airplane remained in normal law and maintained the flight envelope protections, one of which protects against a stall.
Full report: https://www.ntsb.gov/investigations/...ts/aar1003.pdf

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Old 9th Jul 2020, 12:48
  #1594 (permalink)  
 
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Quote:
Starting the APU early in the accident sequence proved to be critical because it improved the outcome of the ditching by ensuring that electrical power was available to the airplane. Further, if the captain had not started the APU, the airplane would not have remained in normal law mode.
[...]
The NTSB concludes that, despite being unable to complete the Engine Dual Failure checklist, the captain started the APU, which improved the outcome of the ditching by ensuring that a primary source of electrical power was available to the airplane and that the airplane remained in normal law and maintained the flight envelope protections, one of which protects against a stall.
In Flight 1549 there are two aspects. They had damaged Engines with low N1,N2 not failed Engines. They had all hydraulic systems working but generators could could have got disengaged unpowering the AC1 &AC2 getting in ELEC EMER config and alternate law which was avoided by APU start. In PK8303 case it is at least clear that their both generators failed because RAT was deployed and they were in alternate law. If they had the required hydraulic pressures in Green and Yellow systems is not known, left engine the report said needs investigation. If they didn't have then they would have remained in alternate law even with APU on due to G+Y fail. If they had and AC buses were intact APU was able to connect then they would have been in Normal Law. But then they would have activated alpha protection to hit the buildings even harder. It even happened to flight 1549. Sullenburger had dropped his 19kts below VLS which triggered alpha protection . So either way APU or no APU PK8303 was doomed.

Last edited by vilas; 9th Jul 2020 at 16:45.
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Old 9th Jul 2020, 18:55
  #1595 (permalink)  

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The decision making was obviously there with Capt. Sullenberger and J. Skilles, aiming outside the built-up area.
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Old 9th Jul 2020, 20:12
  #1596 (permalink)  
 
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I've never known a pilot not to do that, if able
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Old 9th Jul 2020, 20:47
  #1597 (permalink)  
 
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I recall from the movie (assume accurate) that Sully started APU nearly immediately, and also that on QRH it was actually pretty far down the list of things to do, like 15th or 17th, such that you wonder how things might have worked out if they’d gone step by step thru QREf (or if they’d even had time to do so...)
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Old 9th Jul 2020, 21:04
  #1598 (permalink)  

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Originally Posted by lomapaseo View Post
I've never known a pilot not to do that, if able
That may have changed on the day this thread started.
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Old 10th Jul 2020, 01:56
  #1599 (permalink)  
 
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It’s pretty ingrained in almost all of us, apparently, to fire the APU at the hint of a dual (or even a single!) engine hiccup. However, I’m with vilas on this one: it wouldn’t have made any significant difference in the final outcome.

MikeSnow: Notice the report says “normal law”. As vilas pointed out, this means the aircraft always had at least one normal generator working, meaning the APU generator came online before the second generator got offline (if it ever did, as one of the engines had only partial thrust loss). As sufficient hydraulic pressure is generated with very low N2 values, losing only one hydraulic system (I.e. the one supported by the completely dead engine) doesn’t get the aircraft out of normal law, and most likely if the generator wasn’t kicked offline, then the partially failed engine was still supporting its hydraulic system.

It seems the PIA case is quite different, as the photos of the airplane with the gear up show the RAT deployed, meaning it did lose power to both AC busses (read: generators). If I venture a little analysis of the altitude and speed charts in the preliminary report, we see the airspeed after the go around never got above 250-ish, then it goes down to about 200 and stays there until the end of the plot. The point where the speed starts to decrease from 250 could be where the first engine failed, then they seem to have traded speed for altitude (since that one kept going up), speed stabilized in regions consistent with normal green dot speeds, and it’s just one mile (starting from the runway) since the speed starts to go down to the end of the plot, which is when the second generator got offline (I.e.: second engine failure). You need a whole minute to get the APU running and online in the A320. There was never going to be enough time to get it running. And even then, the second engine still failed, so they would’ve gone into alternate law anyway. They only would’ve had double instruments, the critical bits of the plane would be the same as without APU. And obviously that didn’t help them before...

lomapaseo: I think yours is a very difficult question to answer with the information we have available, at least to guesstimate where this particular aircraft would have (crash)landed. They weren’t at typical values of speed, altitude and configuration to try and estimate the flight path. And I guess it all depends on when did they lower the gear

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Old 10th Jul 2020, 10:21
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Originally Posted by Escape Path View Post
It’s pretty ingrained in almost all of us, apparently, to fire the APU at the hint of a dual (or even a single!) engine hiccup. However, I’m with vilas on this one: it wouldn’t have made any significant difference in the final outcome.
I agree, although it probably wouldn't have hurt to attempt to start it. My reply to vilas was only to counter this part of his post: "Sully started APU from memory as good airmanship to get an engine going but once that didn't happen he also got no other help from APU.". Because according to the NTSB the APU helped with more than that, in that particular situation.

Last edited by MikeSnow; 10th Jul 2020 at 10:33.
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