PIA A-320 crash in Karachi

[mtr75 653]

48 minutes ago, Ray Proudfoot said:

No because they reports facts and not speculation. I have no wish to hear the tapes. If you want to discuss known facts that's fine but leave it at that.

Be careful. Every accident is different.

Fair enough. 

Known facts:

At 5 miles they were 3,500 feet AGL. Very unstable approach ensued (1,700 FPM descent). They did not report any issues to ATC during the first approach. ATC offered them a 30-degree vector, pilot refused. (Allowing some speculation, that was because ATC knew the plane was very high). Flap overspeed warning is heard on ATC tapes (again, very unstable approach). Somehow, some way, the plane hit the runway without the gear down. Pictures clearly show huge scrapes on the bottoms of the engine nacelles, smaller in the front, extending out toward the rear (indicative of hitting the runway in a nose-up attitude). Pilots executed a go-around. ATC queried them about hitting the ground. ATC assigned 3,500, they only made 2,000. Both engines quit. Emergency declared. Plane came down in what a320 pilots describe as the highest nose-up pitch attitude that the Airbus envelope protection system would allow. Pictures, videos, ATC tapes and ADSB flight track to support all of the above, all publicly available.

Not a pretty picture. 

Edited May 23, 2020 by mtr75

[threexgreen 3,139]

4 hours ago, Ray Proudfoot said:

This is what the BBC are reporting. Very little of your post is in theirs.

To be honest, mainstream media are really not the best source for aviation related things, especially accidents. They frequently get things completely wrong when reporting about aviation and accidents. The fact that much of what @mtr75 said doesn't appear in the BBC article doesn't mean it's not true, it simply comes down to the target audience which is the general public and most of this audience doesn't have a clue about flap overspeeds, unstable approaches, RATs, etc. so you're not going to find this sort of info in mainstream media. Aviation related media is much more in-depth and the Aviation Herald for example has more information now than mainstream media will likely ever report.

 

9 hours ago, Christopher Low said:

It's sad to think that they may actually have made it to the airfield if they had kept the gear retracted..... 😢

The weather wasn't doing them much of a favor either. Very hot (35°C) and low pressure (Q1004).

[Ray Proudfoot 8,954]

@threegreen, I agree mainstream media won’t post the technical stuff but given the crash occurred less than 30 hours ago I wouldn’t expect any responsible media outlet to publish uncorroborated info. The black boxes will be with the Pakistan accident people and they won’t be that quick to release info. 

I’m sure in good time the reasons will be made public and people can debate knowing all the facts. Lots of speculation mixed with some known info at the moment.

[threexgreen 3,139]

37 minutes ago, Ray Proudfoot said:

uncorroborated info.

What he said in his last post is not uncorroborated info though, it's known.

It has been confirmed by runway inspection that the engines scraped along the runway. Something went horribly wrong on that first approach. Though I don't understand why, if eyewitnesses and tower staff saw the landing attempt scraping the engines, there are no reports on whether the gear was down on that approach and prematurely retracted or whether it was retracted all along.

Quote

On May 23rd 2020 Karachi Airport reported based on CAA inspection report that the runway inspection revealed scrape marks of the left engine start 4500 feet down the runway, the right engine scrape marks begin 5500 feet down the runway. About 6000-7000 feet past the runway threshold the scrape marks end.

http://avherald.com/h?article=4d7a6e9a&opt=0

CVR and FDR have also been recovered.

Edited May 23, 2020 by threegreen

[Ray Proudfoot 8,954]

@threegreen, I’m not here to debate the crash. I just wanted to ensure facts were debated and not speculation.

[SAS443 1,723]

2 hours ago, threegreen said:

Very hot (35°C) and low pressure (Q1004).

I will give you the temperature, that worked against them.

 But Q1004 is hardly anything? ISA deviation of the temperature caused density altitude to be 2.500ft.  (aerodrome elevation is just 100ft). Whereas the QNH penalty is a minor 250ft(ish)

[Chock 17,769]

2 hours ago, Ray Proudfoot said:

 responsible media outlet

Let us know when you find one. 🤣

[SierraDelta 1,342]

16 hours ago, mtr75 said:

....

Not a pretty picture. 

None of which though makes the last part of your first post in this thread, starting with: "Ladies and gentlemen, welcome ..." any less distateful.

[Chock 17,769]

4 hours ago, SierraDelta said:

None of which though makes the last part of your first post in this thread, starting with: "Ladies and gentlemen, welcome ..." any less distateful.

In fairness, this forum does have the stated intent that it is: 'for the discussion of things you might discuss when going into an airport hangar'.  With that in mind, I've got to be honest and say the comment is pretty much in-keeping with the kind of thing I do hear in that environment on a pretty regular basis. The ramp is quite a 'blokish' environment, and whilst I don't always like everything I hear when I am working there, the truth is that you do have to have a bit of a thick skin in that kind of workplace. 

The comment was prefaced with what it seems is quite a reasonable speculative assessment of what may have occurred. Inevitably, on an aviation forum such as this, whenever such an incident occurs, there'll be a bit of speculation and opinion as to what went on, in fact even in official investigations, lines of enquiry do tend to start with speculative theories about likely scenarios, so that they can either be eliminated or looked into in greater detail. So whilst I agree, and did mention on a prior post, that it perhaps wasn't the most tactful of comments, I don't think it was entirely out of place given the 'discussed in a hangar' nature of this forum.

Even given the fact that what we know about the incident is largely from media reports, press statements from the airport, recordings from ATC and photographs from plane spotters, rather than official accident investigatory sources, it does appear to be fairly incontravertibly evident that the aeroplane suffered a dual pod strike with significant damage to the (very thin) bottom panels of both engine nacelles, which almost certainly damaged the ancillary equipment drive mechanism on the lower part of the engines. This is such an unusual incident that we are pretty much forced to conclude the most likely explanation for its cause, is an error on the crew's part. At this point we cannot say this is a certainty, since we don't have all the facts, and it is worth bearing in mind that since many aeroplanes have been grounded for some time in the current pandemic lockdown, that it could also have been a maintenance issue, but I'd say there was a fair chance some errors on the crew's part are something to do with the cause of the accident.

Edited May 24, 2020 by Chock

[mtr75 653]

44 minutes ago, Chock said:

In fairness, this forum does have the stated intent that it is: 'for the discussion of things you might discuss when going into an airport hangar'.  With that in mind, I've got to be honest and say the comment is is pretty much in-keeping with the kind of thing I do hear in that environment on a pretty regular basis. The ramp is quite a 'blokish' environment, and whilst I don't always like everything I hear when I am working there, the truth is that you do have to have a bit of a thick skin in that kind of workplace. 

The comment was prefaced with what it seems is quite a reasonable speculative assessment of what may have occurred. Inevitably, on an aviation forum such as this, whenever such an incident occurs, there'll be a bit of speculation and opinion as to what went on, in fact even in official investigations, lines of enquiry do tend to start with speculative theories about likely scenarios, so that they can either be eliminated or looked into in greater detail. So whilst I agree, and did mention on a prior post, that it perhaps wasn't the most tactful of comments, I don't think it was entirely out of place given the 'discussed in a hangar' nature of this forum.

Even given the fact that what we know about the incident is largely from media reports, press statements from the airport, recordings from ATC and photographs from plane spotters, rather than official accident investigatory sources, it does appear to be fairly incontravertibly evident that the aeroplane suffered a dual pod strike with significant damage to the (very thin) bottom panels of both engine nacelles, which almost certainly damaged the ancillary equipment drive mechanism on the lower part of the engines. This is such an unusual incident that we are pretty much forced to conclude the most likely explanation for its cause, is an error on the crew's part. At this point we cannot say this is a certainty, since we don't have all the facts, and it is worth bearing in mind that since many aeroplanes have been grounded for some time in the current pandemic lockdown, that it could also have been a maintenance issue, but I'd say there was a fair chance some errors on the crew's part are something to do with the cause of the accident.

@Chock, I appreciate your comments and agree. Aviation humor, or sarcasm, is perhaps the darkest kind, and anyone who is around airplanes knows they may wind up the brunt of it someday if we do something stupid. 

All that being said, confirmed gear-up on the first landing (albeit right on centerline - see above). They didn't notify ATC of a gear problem, so its pretty likely they just plain forgot it. 

This isn't the first pilot that tried going around after a gear up. It very rarely turns out well. When you see sparks, the insurance company owns the plane. Just shut it down. 

As Rod Machado once said, if it requires full power to taxi, you might have forgotten the gear. 

Edited May 24, 2020 by mtr75

[threexgreen 3,139]

14 hours ago, SAS443 said:

I will give you the temperature, that worked against them.

 But Q1004 is hardly anything? ISA deviation of the temperature caused density altitude to be 2.500ft.  (aerodrome elevation is just 100ft). Whereas the QNH penalty is a minor 250ft(ish)

I would argue that 250 ft can make quite a difference if you're trying to glide your way past the last rows of buildings aiming for the field behind. They weren't far away from clearing the residential area and if you factor in gear down, AOA too high for an optimal glide path (judging by the video footage), high temperature plus an additional ~ 250 ft penalty due to low pressure I wouldn't dismiss the 250 ft penalty. I'm not making any assessment as to whether it was possible or not to make it to the field behind the buildings, but since they were rather close I feel every bit could potentially play out to be making a difference.

[threexgreen 3,139]

This is just new in the AH article. http://avherald.com/h?article=4d7a6e9a&opt=0

Quote

On May 24th 2020 Pakistan's media quote a CAA official speaking on condition of anonymity that the aircraft made two attempts to land. During the first approach it appears the landing gear was still retracted when the aircraft neared the runway, the pilot had not indicated any anomaly or emergency, [...]

On May 24th 2020 a spokesman of the airline said, the landing gear had not been (partially or fully) lowered prior to the first touch down. The crew did not call out the standard operating procedures for an anomaly and no emergency was declared. Most likely the crew was not mentally prepared for a belly landing and went around when they realized the engines were scraping the runway.

Also pictures of the scrape marks on the runway:

[Chock 17,769]

Looks very much like if they'd just closed the throttles and accepted that they'd screwed up, they'd probably have had a - admittedly career-ending - survivable belly landing.

[SAS443 1,723]

1 hour ago, threegreen said:

I would argue that 250 ft can make quite a difference if you're trying to glide your way past the last rows of buildings aiming for the field behind. They weren't far away from clearing the residential area and if you factor in gear down, AOA too high for an optimal glide path (judging by the video footage), high temperature plus an additional ~ 250 ft penalty due to low pressure I wouldn't dismiss the 250 ft penalty. I'm not making any assessment as to whether it was possible or not to make it to the field behind the buildings, but since they were rather close I feel every bit could potentially play out to be making a difference.

But that is not how it works. They were never 250ft lower due to the QNH being 1004HPa. Correct setting of QNH ensures AD. ELEV. will be indicated during landing.

I am talking about performance parameters (lift, thrust, weight and drag), which would reflect that AD ELEV on this day would be 2.750ft higher up. So if it was colder, the engines would probably be able to take them to higher  (true) altitude before quitting on them, giving them more potential energy. Had it been 34C instead 35C that would be enough to basically cancel out the lower QNH... I will maintain that QNH is not the big issue - temperature is.

As a side note: warmer than ISA  will make indicated altitude < true altitude. But since the air is less dense TAS will increase and effect on L/D is unchanged (you will go faster and lose altitude faster)

[threexgreen 3,139]

2 hours ago, SAS443 said:

But that is not how it works. They were never 250ft lower due to the QNH being 1004HPa. Correct setting of QNH ensures AD. ELEV. will be indicated during landing.

I am talking about performance parameters (lift, thrust, weight and drag), which would reflect that AD ELEV on this day would be 2.750ft higher up. So if it was colder, the engines would probably be able to take them to higher  (true) altitude before quitting on them, giving them more potential energy. Had it been 34C instead 35C that would be enough to basically cancel out the lower QNH... I will maintain that QNH is not the big issue - temperature is.

As a side note: warmer than ISA  will make indicated altitude < true altitude. But since the air is less dense TAS will increase and effect on L/D is unchanged (you will go faster and lose altitude faster)

The reply above was probably not very clear on what I meant because of the way I used the 250 ft. I wasn't trying to indicate they were 250 ft higher or lower in itself, but rather that the difference in pressure altitude, even if just 250-ish ft, and its penalty on performance may play a role in just making it or not, especially if combined with one of the other factors (lower AOA for better gliding, for example).