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PIA A320 Crash Karachi

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PIA A320 Crash Karachi

Old 24th May 2020, 14:27
  #421 (permalink)  
 
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Originally Posted by Milvus Milvus
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
  #422 (permalink)  
 
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Originally Posted by henra
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
  #423 (permalink)  
 
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Originally Posted by FatPilot
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
  #424 (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
  #425 (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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Old 24th May 2020, 14:48
  #426 (permalink)  
 
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From the Boeing FCTM:

‘Retract the landing gear
after a positive rate of climb is indicated on the altimeter.’

So if my company wants me to say ‘positive rate’, that’s fine by me. Yes, I do know that I need to look at the big white needle going clockwise or the alt tape numbers scrolling upwards.

Out of interest, as a non Bus driver, what does their FCTM equivalent say?
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Old 24th May 2020, 15:01
  #427 (permalink)  
 
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Nah. Semantics really.
”positive rate” as said in many SOP’s around the globe, simply means that a positive rate of climb has been established. It is the abbreviated form of “positive rate of climb”.
Same as: “gear down, flaps 20”, which means “select the gear lever down and subsequently select flaps 20, please”
Let’s not get into this. Just make sure you do a go-around when too hot and high.
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Old 24th May 2020, 15:05
  #428 (permalink)  
 
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So far then, appears aircraft approach was not ideal yet decided a bit late to go-around. By that time aircraft engine cowls had "touched" the runway, too much speed and not enough runway left so decided on a second approach not realising that the AGB's were not functioning normally. Moral of this may be - get your approach criteria correct including flap position and gear extended before decision height. Two captains and they could not get this right.
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Old 24th May 2020, 15:10
  #429 (permalink)  
 
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Originally Posted by giggitygiggity
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?
It is surely on the high side. Would have been OK if they had space to dissipate the energy for the final approach. But with that descent rate even with engines at idle you will arrive at 10k on the high side of the speed range. And in this case at 10 kft they were so close to the airport that they had to even further steepen the approach. So looking at that graph it indicates that they probably started the descent a few minutes too late for the given circumstances. For whatever reason. Possibly they were expecting a holding pattern or a much wider circuit?
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Old 24th May 2020, 15:14
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Originally Posted by krismiler
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.
Maybe they tried to lower the gear even earlier, e.g. already during the steep descent from 10k? At that altitude and looking at the general descent profile, 260kts would not appear completely unconceivable. It is at least an interesting theory. The recorders will tell the story.
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Old 24th May 2020, 15:45
  #431 (permalink)  
 
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Originally Posted by henra
It is surely on the high side. Would have been OK if they had space to dissipate the energy for the final approach. But with that descent rate even with engines at idle you will arrive at 10k on the high side of the speed range. And in this case at 10 kft they were so close to the airport that they had to even further steepen the approach. So looking at that graph it indicates that they probably started the descent a few minutes too late for the given circumstances. For whatever reason. Possibly they were expecting a holding pattern or a much wider circuit?
It might perhaps be slightly on the high side but calling it incredible is somewhat sensationalist.

This is not a boast and I'm sure you'll label me as an accident waiting to happen, but I looked up the last flight I did on the A320 to Tenerife (sadly back in march), I descended from 39,000ft to 10,000ft in 11 mins after getting a very nice (and requested) short cut from ATC - 2,600ft/min average. I managed to land without crashing into Las Americas. There was however just (again sadly) 6 of us on board.
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Old 24th May 2020, 16:01
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Thanks Aviation Herald.

So it did do a double pod scrape with the gear up, that will very probably have destroyed the IDGs and hydraulic engine driven pumps. AC1 and AC2 probably lost, hence RAT deployment. B HYD system only.

Since the gear is down, we're straight into direct law, protections lost. That would be a very challenging configuration for a good crew to fly on their lucky day, for the initial baulked landing and of course the subsequent approach.

Apparently high nose attitude in the final video would suggest an attempt to stretch the glide, with obvious results.
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Old 24th May 2020, 16:03
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From the point of view of 'Human Factors'
1. The first is observed when the crew says that they are comfortable at 3500 feet at 5 miles. Here the crew is getting self trapped into being committed for landing
2. Second is when they announce that they are established on ILS, which they are not. Making such announcements would put lot of pressure on the crew to somehow push through the landing.

Ego could also have been triggered here. Still, the landing could have been hacked but for the fact that the gear was missed. This resulted in irretrievable situation.
Tunnel vision and get homeitis have a role.

Such mistakes though not common do happen. Here the crew were unlucky to have additional and overlooked problem of gear.
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Old 24th May 2020, 16:19
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Originally Posted by giggitygiggity
It might perhaps be slightly on the high side but calling it incredible is somewhat sensationalist.
This is not a boast and I'm sure you'll label me as an accident waiting to happen, but I looked up the last flight I did on the A320 to Tenerife (sadly back in march), I descended from 39,000ft to 10,000ft in 11 mins after getting a very nice (and requested) short cut from ATC - 2,600ft/min average.
No I won't call you an accident waiting to happen. It is fine as long as you have got enough space and time left for the final approach to dissipate the energy and stabilise and don't have to rush things. This is what was obviously missing here. Even after this rather quick descent from 35k the equation didn't add up. They had to steepen the aproach further and apparently couldn't get rid of the energy which in turn may have occupied them so much that it may have contributed to them making a very basic and stupid mistake. Moreover due to the high state of energy they only touched the runway after ~5000ft, which might have contributed to them trying to go around instead of putting it down. The choice of a tight curcuit over congested terrain was also obviously not the best choice in the given circumstances. It appears they got behind the airplane and never managed to catch up again. This appears one nice example of the holes in the cheese lining up and will probably be a shining example in future training/CRM curriculae.
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Old 24th May 2020, 16:25
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Originally Posted by henra
They had to steepen the aproach further and apparently couldn't get rid of the energy which in turn may have occupied them so much that it may have contributed to them making a very basic and stupid mistake.
Not having the gear down would have also made it difficult to slow down and stay on the glideslope.
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Old 24th May 2020, 16:42
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3500 ft at 5NM is not doable in an A320. If you want to try, you need to start with gear down and flaps full. Still you will end up with an increasing speed. More so if you do this without gear down.
Every professional pilot knows this.
So, why did they try? What caused such a major breakdown in common sense?

And why are we not allowed to talk about the elephant in the room (or cockpit)?

Last edited by ManaAdaSystem; 24th May 2020 at 16:54.
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Old 24th May 2020, 16:48
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Originally Posted by henra
Wow!.
From 35k to 10k ft in <13minutes. And then from 10k to 2k in less than two minutes.
From the FR24 .csv file linked earlier, looks like they left FL340 at about 09:15:47Z:



They descended through FL100 at 09:30:18Z:



Descending 24000 feet in 14:31 gives a little under 1700 feet per minute, fairly reasonable I would say. Check my math(s), like timezones, this stuff is easy (for me) to mess up.

On the other hand from FL100 to FL19 (these Mode-S altitudes are all referenced to QNE so the differences should be right even though corrections need to be added for QNH and QFE altitudes) looks like 162 seconds to lose 8100 feet or about 3000 fpm.




DaveReidUK posted this plot of the altitude data for the last few minutes of the flight:



And unworry posted this plot with a derived rate of descent:


Last edited by Airbubba; 24th May 2020 at 16:59.
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Old 24th May 2020, 17:02
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IMHO the ONLYRELIABLEINDICATION

that should be looked at and followed

is an INCREASE in ALTITUDEON the ALTIMETER,

which confirms a ”POSITIVE CLIMB !”



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

Totally agree. You watch the VSI at rotate. Disturbed static air. The VSI gives erroneous readings, albeit momentarily. . Watch the VSI when the gear doors open and close. If you saw that you wouldn't rely on a vsi again, for positive climb. Notice i stated positive CLIMB, not rate.
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Old 24th May 2020, 17:03
  #439 (permalink)  
 
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Originally Posted by Greek God
With regard to this particular event and many more I have long wondered why Towers (especially at major airports) do not seem to have continuous CCTV coverage of every approach and threshold.

Also, in the absence of any notified emergency, should it not be SOP that the ATCO called a GA for a commercial airliner on short final with no gear?
Good Call, It wouldn't cost much to set up.
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Old 24th May 2020, 17:13
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Originally Posted by Airbubba
Descending 24000 feet in 14:31 gives a little under 1700 feet per minute, fairly reasonable I would say. Check my math(s), like timezones, this stuff is easy (for me) to mess up.
No, looking at the discrete data your maths do look correct. It is easy to misjudge the timings from the graphs a bit, which I obviously did.
OK, 1700fpm seems reasonable. That should be roughly what an A320 does in flight idle.
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