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PIA A320 Crash Karachi

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PIA A320 Crash Karachi

Old 24th May 2020, 12:24
  #401 (permalink)  
 
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Is it possible that the gear could have been lowered early, out of normal sequence, to increase drag, then retracted instead of lowered at the point where it would normally have been lowered?

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Old 24th May 2020, 12:36
  #402 (permalink)  
 
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Originally Posted by Teddy Robinson View Post
The Smartlynx A320 incident at Tallinn 28th Feb 2018 has been mentioned previously on this thread.
Whilst an underlying technical issue led to the main event (aircraft contacted the runway once the gear had been selected up), both engines subsequently failed shortly thereafter.
That's accurate if the main event is considered to have been the EFCS pitch control failure. If with main event you mean the wheels in transit ground contact, then the report makes it quite clear that the EFCS failure led to the crew failing to control pitch proparly for 36 seconds as they didn't understand at all that pitch was in manual reversion through the THS control with the trim wheel. The report also speculates (altough doesn not test that hypothesis) that ground contact would still have been avoided without the unexplained selection of idle thrust for 4 seconds before the ground contact.

None of that probably has anything to do with the thread accident, but it's important to note that a “technical issue” was not even close to the only cause of the Tallinn accident you linked.
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Old 24th May 2020, 12:37
  #403 (permalink)  
 
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Why has there been so little comment on the fact that they were offered a 360 degree orbit to lose height on the original approach. "Turn left onto 330 ..." (i.e attacking heading to regain the localiser )?
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Old 24th May 2020, 12:55
  #404 (permalink)  
 
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There’s mention that they might have lowered gear levers at too high a speed, such that protections did not allow gear to go down. Lever would have to be recycled and speed reduced first.

So they thought they had gear down, but didn’t. Possible?
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Old 24th May 2020, 12:58
  #405 (permalink)  
 
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Originally Posted by Dropp the Pilot View Post
Two wrong statements in less than twenty words - pretty impressive even for a thread which is wanna-bee infested to a degree not often seen.

Neither of these things are "positive rate". A V/S trend is a measure of vertical acceleration. It will happily read a positive vertical rate with both main gear planted on the runway with say, a gross error in take-off performance calculations or wind shear. RA is valueless for rate as the reading which the pilots see is a product of an algorithm of pitch attitude and gear tilt and is by no means a direct reading of actual height.

The ONLY measure for positive rate is a sustained and progressive increase in the altitude displayed on the altimeter.

Should you doubt any of this, consult any FCTM from a company called Boeing. They've been doing this stuff for quite some time.
Numerous wrong statements in that post including a misunderstanding of the RA system AND the IVSI.
Boeing do not refer to rate; they refer to climb - on the altimeter.
Yes, yes, feel free to check any Boeing manual however if you want relevant information on this event may I suggest you try something written by Airbus.
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Old 24th May 2020, 13:02
  #406 (permalink)  
 
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Originally Posted by Airbubba View Post
Here's the altitude plot from FR24:

Wow!.
From 35k to 10k ft in <13minutes. And then from 10k to 2k in less than two minutes. Somehow this f*ck up bgean to start already back at 35k. And from 10k on it became worse. How on Earth did they think they would dissipate all that energy?! OK by putting out the flaps above VFE. But surely can't have been the plan!?
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Old 24th May 2020, 13:05
  #407 (permalink)  
 
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Originally Posted by scotbill View Post
Why has there been so little comment on the fact that they were offered a 360 degree orbit to lose height on the original approach. "Turn left onto 330 ..." (i.e attacking heading to regain the localiser )?
Because the PF ignored the offer and conitinued to chase the profile. It was commented on previously.
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Old 24th May 2020, 13:11
  #408 (permalink)  
 
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Some notes taken from various Pakistani press sources:

Both recorders were found on Friday. The FDR will be read in France by the BEA.

There will be at least three independent investigations. The first by the Pakistani AAIB. The second by the Pakistani military. The third by Airbus (Note A0283: that would be unusual, they probably mean that Airbus will be a party to the safety investigation - but they focus on the independence).

There are 2 certain survivors from the plane, both named males. There is one note of a named female survivor (Note A0283: which was on the published passenger list, and not being the named female model which was mentioned in earlier reports).

One official source shows 1 dead and 4 injured on the ground.

About the aircraft: Aviation authorities on Saturday released an executive summary of the aircraft, revealing certain facts about its maintenance and operations history. According to the summary, the Airbus A320-214 aircraft was 16 years old and up till now, had flown for 47,124 hours. The aircraft’s last flight before Friday’s ill-fated one between Lahore and Karachi, took place just a day ago when it ferried Pakistani citizens stranded in Muscat to Lahore. The aircraft last underwent a routine check on March 21 of 2020 and major check on October 19 of 2019. Although it was grounded between March 22 and May 7, this was on account of Covid-19 and not for any airworthiness issues. The summary stated the aircraft suffered from no engine, landing gear or major aircraft systems defects and had operated 6 flights since being pressed back into service on May 7. Both of the aircraft’s engines were installed last year in February and May. Its landing gear was installed in October 2014 and was due for removal and overhaul in October 2024.

Last edited by A0283; 24th May 2020 at 13:41.
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Old 24th May 2020, 13:34
  #409 (permalink)  
 
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From elsewhere...

"If you lower the L/G above 260kts, the L/G Safety valve will prevent the Green HYD from lowering the gear, but the L/G Lever will go down. Now once below 260kts, will the L/G come down on its own? Or does the Lever need to be recycled?"

That's a very good question. If we believe an old FCOM, the lever has to be recycled to get the gear down below 260kts. The valve won't open if the lever just stays down when the speed goes below 260kts.
That would be a very good explanation for the gear up landing (lever down at high speed to increase drag, but gears stay up). Then the alarm priority kept the "too low gear" off until flare, to late to avoid contact...
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Old 24th May 2020, 13:41
  #410 (permalink)  
 
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If the airline spokesman quote is accurate, the pilots are being hung out to dry. There must be very limited circumstances where the gear was still up but no warnings sounded.
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Old 24th May 2020, 13:43
  #411 (permalink)  
 
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Originally Posted by krismiler View Post
Even one warning during an approach is bad enough and suggests that a go-around would be a good idea.

Multiple warnings would surely remove any doubt about continuing to land and are best prioritised and delalt with once a safe flight path has been established and the missed approach procedure complied with.

Fear of loss of face from going around may well have played a part, culturally it may only be acceptable for the senior pilot to decide whether to continue, and unsolicited advice from a junior would be regarded unfavourably. When CRM is really bad it might even cause the senior pilot to feel he has to prove a point and establish his authority.


With engine bypass ratios becoming higher and ground clearance being reduced, has adequate consideration gone into the location of vital components such as pumps, gearbox’s and supply lines ? Whilst space is obviously constrained, having vital systems in a vulnerable position should be avoided.
Best to keep future aircraft designs out of this preliminary cause discussion

presumptive design is typically based on historical experience. Things to do with oil loss or maintenance errors are mitigated by placing the gearbox and other accessories under the engine.
Severe pod scrapes followed by continued flight are relatively rare in comparison
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Old 24th May 2020, 13:46
  #412 (permalink)  
 
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Originally Posted by Milvus Milvus View Post
That would be a very good explanation for the gear up landing (lever down at high speed to increase drag, but gears stay up). Then the alarm priority kept the "too low gear" off until flare, to late to avoid contact...

​​​​​​Interesting scenario. But they surely would not get three greens?

That being sais in the confusion they might also have missed that cue
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Old 24th May 2020, 13:51
  #413 (permalink)  
 
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Originally Posted by atakacs View Post
​​​​​​Interesting scenario. But they surely would not get three greens?

That being sais in the confusion they might also have missed that cue
True.
Also, even with the Gear Up they would get the ECAM WHEEL PAGE at 800ft on the Lower Ecam along with six Red Triangles to show wheels up.
It would mean no Landing Checks carried out either.
In the Circumstances, although all this seems remote it could just happen.
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Old 24th May 2020, 14:14
  #414 (permalink)  
 
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Originally Posted by EFHF View Post
None of that probably has anything to do with the thread accident...
While the reasons for the ground contact in the case of the Smartlynx accident were indeed very different, I think you will find that the causes for the dual engine failure after the ground scrape will be very similar, most likely mechanical damage to the AGB and the consequent loss of engine oil. I would consider it very relevant to the accident under discussion.
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Old 24th May 2020, 14:20
  #415 (permalink)  
 
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Originally Posted by EFHF View Post
That's accurate if the main event is considered to have been the EFCS pitch control failure. If with main event you mean the wheels in transit ground contact, then the report makes it quite clear that the EFCS failure led to the crew failing to control pitch proparly for 36 seconds as they didn't understand at all that pitch was in manual reversion through the THS control with the trim wheel. The report also speculates (altough doesn not test that hypothesis) that ground contact would still have been avoided without the unexplained selection of idle thrust for 4 seconds before the ground contact.

None of that probably has anything to do with the thread accident, but it's important to note that a “technical issue” was not even close to the only cause of the Tallinn accident you linked.
To be fair, I have used the term "main event" perhaps incorrectly in context with the set of circumstances we are discussing at the moment. I fully concur, the ELAC failures and loss subsequent loss of pitch control in the Smartlynx accident have no direct relation to this accident, however, the runway contact itself to the point of dual engine failure does seem worthy of further discussion.


TR
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Old 24th May 2020, 14:27
  #416 (permalink)  
 
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Originally Posted by Milvus Milvus View Post
From elsewhere...

"If you lower the L/G above 260kts, the L/G Safety valve will prevent the Green HYD from lowering the gear, but the L/G Lever will go down. Now once below 260kts, will the L/G come down on its own? Or does the Lever need to be recycled?"

That's a very good question. If we believe an old FCOM, the lever has to be recycled to get the gear down below 260kts. The valve won't open if the lever just stays down when the speed goes below 260kts.
That would be a very good explanation for the gear up landing (lever down at high speed to increase drag, but gears stay up). Then the alarm priority kept the "too low gear" off until flare, to late to avoid contact...
ECAM L/G GEAR NOT DOWNLOCKED will appear if gear sequence is not completed after 30 seconds. (for any reason)

FCOM says to recycle gear handle in that situation. The CRC can be silenced and the ECAM can be cleared purposely or inadvertently.

A few years back I had an airplane where the safety valve stuck in the closed position. To say the least it was quite a shock when I called for Gear down to the FO and it failed to come down. I don’t know how any pilot could miss that cacophony and light show. At the time the procedure was to recycle the gear handle up to five times. On the third try it came down.

i don’t think in this case that happened.
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Old 24th May 2020, 14:34
  #417 (permalink)  
 
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Originally Posted by henra View Post
Wow!.
From 35k to 10k ft in <13minutes. And then from 10k to 2k in less than two minutes. Somehow this f*ck up bgean to start already back at 35k. And from 10k on it became worse. How on Earth did they think they would dissipate all that energy?! OK by putting out the flaps above VFE. But surely can't have been the plan!?
The second half of that aside. Is 35k to 10k in 13 mins that incredible? 25,000 ft to lose in 13 mins, ~2000ft/min?
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Old 24th May 2020, 14:37
  #418 (permalink)  
 
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Originally Posted by FatPilot View Post
Numerous wrong statements in that post including a misunderstanding of the RA system AND the IVSI.
Boeing do not refer to rate; they refer to climb - on the altimeter.
Yes, yes, feel free to check any Boeing manual however if you want relevant information on this event may I suggest you try something written by Airbus.
Very sad what happened...
Hopefully, we may learn some things...

IMHO the ONLY RELIABLE INDICATION

that should be looked at and followed

is an INCREASE in ALTITUDE ON the ALTIMETER,

which confirms a ”POSITIVE CLIMB !”

So, forget the VSI (and all others…) and look at the ALTIMETER !

It’s a paradox…

Just ask a pilot: ”Where do you see that you are climbing?”

And 9 out of 10 will reply: ”On the vertical speed indicator!”

Hence: That’s where most are looking… At the VSI.

(However, the VSI is used for establishing or maintaining a certain rate of climb or descent…)

Whilst it is that simple,

Still nowadays it takes me numerous briefings and sessions,

and almost every half year I have to repeat it,

to try to really ’delete’ the call: ”positive rate !” from the brains of experienced pilots,

coming from everywhere and from different established airlines,

flying Airbus and Boeing and others...

Even when they ’seem’ to understand all the issues involved.

It’s just because for many ’rate’ has been ’slammed into’ their minds during their very first flying lessons,

(as was done to me in the early ’sixties’)

their eyes are looking at the wrong instrument…

(A totally different, but similar issue is 'deleting' the "Ready for take off !" call, to be replaced by: "Ready for DEPARTURE !" ...)

Just always learning, learner . . .
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Old 24th May 2020, 14:41
  #419 (permalink)  
 
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That's a very good question. If we believe an old FCOM, the lever has to be recycled to get the gear down below 260kts. The valve won't open if the lever just stays down when the speed goes below 260kts.
The FCOM isn't too clear on this, and of course we don't have access to the manual for that particular aircraft. Current info is that "Below 260 kt, the hydraulic pressure supply remains cut off as long as the landing gear lever is up." I can't find any reference to having to recycle the lever in the PRO or SYS sections in recent FCOMs, a system chart shows that an indication of speed < 260 kt from ADR 1 or 3 and the lever selected down should open the safety valve and allow gear extension. The procedure may call for recycling the handle but I doubt they had time to refer to the QRH.

If they were 5nm out and going so fast that the landing gear couldn't extend it's unbelievable that they continued, even if they had been on the correct vertical profile they were around 100kts too fast.

With the recorders available and being read by French investigators, together with the marks on the runway we should have an accurate sequence of events fairly soon and won't have to speculate on what happened. We can instead look at WHY it happened.
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Old 24th May 2020, 14:44
  #420 (permalink)  
 
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Reference the 1st approach, allowing to get hot and high by whatever means at five miles, could the crew have decided to ‘chase the profile’ by converting to a visual approach?

Yep they should request/advise ATC That’s what they’re doing, but already behind the curve would that change of procedure mean an increased cockpit workload. I’m thinking in terms of cancelling alarms and warnings possibly already active from the position if the aircraft was being flown assuming an ILS. Would a gear up warning Gpws be cancelled in that scenario? If so and target fixated, working hard to achieve what they already know will be a challenge to complete a ‘hot’ landing, could a gear warning be overlooked or misheard in that scenario?, and the gear subsequently not selected.
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