Pakistan plane crash: Jet carrying 107 people crashes into houses near airport

[Gabriel]

The clip of the plane descending at high AoA looks as though its going too fast to be stalling, it looks like they have enough speed to glide and I wonder why is the nose up?

Why are you saying too fast? In my view they are gliding at minimum speed / maximum AoA. The slower you fly, they higher the AoA needed to sustain flight. Of course all that goes to trash if you stall, so they were not stalled but slightly before stall. Possibly, this is the feat of the flight control computers limiting the AoA to alpha max and blocking the pilots intent to pitch even higher up trying to extend a glide beyond the laws of physics. Somehow similar to the 1st A320 crash, the Air France one in that air show.

[Gabriel]

Oh my god, this is frigging unbelievable. How did the engines contact the ground 5000 ft down the runway and how did they kept them dragging them for 2000 ft?????

I think if you want to intentionally do that, you can't.

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

[Jingogunner]

Video of the craft going down. Sounds like engines were out.

https://www.liveleak.com/view?t=C1MJ3_1590157626

https://www.liveleak.com/view?t=u5vDK_1590165084

The clip of the plane descending at high AoA looks as though its going too fast to be stalling, it looks like they have enough speed to glide and I wonder why is the nose up?

[Evan]

Another crazy hypothesis...

They had problems with the nose gear and they went around normally (there are reports of a go around due to problems with the nose gear, but perhaps it was first go-around before a second one where they dragged the engines).
They could not fix the issue and they decided to land with the nose gear not down and locked.
In their second approach, they thought that they had the gear down but they in fact left them up after the previous troubleshooting.
They either deactivated or ignored the several different gear-not-down warnings, because they expected them anyway when approaching with the nose gear not secured down. We can hear the master caution continuous repeating chime in the ATC recording when they receive the landing clearance. Having the gear not down and locked below 750 ft RA seems to be a reason for this warning, which is not cancelled.
They were already in the flare when they had a last-second "oh shit" moment realizing that the gear was up (3 red, not just the nose gear). They initiated a last second go-around but didn't manage to avoid contacting the runway with the engines, but they did manage to complete the go around and climb out.
The rest is history.

Compelling. If they were working the nose gear problem before the first landing attempt and they were following the L/G GEAR DOWNLOCKED procedure, they would first try cycling the gear and then use the gravity extension crank. That would depressurize the hydraulics, so the doors remain open. In the approach, they would switch off the GPWS (no more alert) and reset the gravity extension crank (to repressurize the system, to prevent gear collapse). If they then aborted that attempt, they might have retracted the gear (though why would they if they were having a gear extension problem?). At that point, because they reset the gravity extension, they would have the gear doors closed as seen in the photo and no too low gear warnings from the GPWS. So, it's plausible, but hard to fathom, that they would erroneously make a second attempt without the gear. I would expect a flare or climb out attitude to result in a tail strike as well but who knows.

I think the far more likely theory is that this was a botched manual go-around where they failed to set TOGA thrust and retracted the gear (again, why?) too soon, lost height and skimmed along the runway for a second or two, long enough to cause fatal engine damage but not enough to slow below flight speed. At least there is some partial precedent for this.

But still crazy.

[xspeedy]

What is unfortunate is so many lives could have been saved if he lined up with 25R. The corner of Model Colony comes in front of 25L. 25R had field.

[ATLcrew]

This past month it seems that the most incredible story will become the one most widely believed. It's bewildering. It blows my mind how naive people have become.

That's been blowing my mind since long before this month.

[ATLcrew]

It's a good question. You recall that Cactus 1549 had Normal Law protections down to the flare, but they also had engine electrical power. The FCOM indicates that on BAT power or on the RAT generator the pitch law reverts to alternate. So that varies depending on whether or not the engines (or the APU) are still able to supply electrical power (I don't think the RAT was deployed in the Hudson ditching). But my research in actual incidents often seems to depart from the FCOM in these situations. Maybe ATL knows.

Maybe he does. Why don't "we" ask him?

[Gabriel]

Another crazy hypothesis...

They had problems with the nose gear and they went around normally (there are reports of a go around due to problems with the nose gear, but perhaps it was first go-around before a second one where they dragged the engines).
They could not fix the issue and they decided to land with the nose gear not down and locked.
In their second approach, they thought that they had the gear down but they in fact left them up after the previous troubleshooting.
They either deactivated or ignored the several different gear-not-down warnings, because they expected them anyway when approaching with the nose gear not secured down. We can hear the master caution continuous repeating chime in the ATC recording when they receive the landing clearance. Having the gear not down and locked below 750 ft RA seems to be a reason for this warning, which is not cancelled.
They were already in the flare when they had a last-second "oh shit" moment realizing that the gear was up (3 red, not just the nose gear). They initiated a last second go-around but didn't manage to avoid contacting the runway with the engines, but they did manage to complete the go around and climb out.
The rest is history.

[Gabriel]

Not sure if this was posted before:https://youtu.be/YuXv1e68Pq0

Is the landing gear visible in this video? (not that it changes much what may have happened in the first approach / go around / runway contact)

[Gabriel]

By the way... they were so close to making it to the field (not to the runway). They crashed 1000 to 2000 ft short of the field where the situation would have likely been much more survivable (like the BA 777 at Heathrow)

[Evan]

Maybe they touched down, started a go around and retracted the gear too early.

I guess this is plausible, but the engine strikes must have been very light, more like engine drags...

Or maybe they started the go-around shortly after landing and didn't add power (like that 777) and the airplane initially climbed, they retracted, but lost speed and started to sink, then they added thrust to recover what they did but not before contacting the ground.

I don't know how or why, but at this point the possibility of them having contacted the runway with the engines seems increasingly probable.

If so, this promises to be interesting. There must be some runway surveillance video.

[Gabriel]

I don't think it's just 'dirty engines'. I wonder if it's due to oil leakage. Do you think composites contacting with an asphalt runway would leave those black marks?

I really have no idea. Perhaps the friction set the composites momentarily on fire?

Do you think they would attempt a gear-up landing without advising ATC?

No, I don't think the first landing was gear up. At least not main gear up. You would never attempt a go-around from that.
That said, there are versions of the nose gear not coming down and you can hear the master warning when the tower clears them to land the first time (i.e. before the go around) which they acknowledge.

Maybe they touched down, started a go around and retracted the gear too early. Or maybe they started the go-around shortly after landing and didn't add power (like that 777) and the airplane initially climbed, they retracted, but lost speed and started to sink, then they added thrust to recover what they did but not before contacting the ground.

I don't know how or why, but at this point the possibility of them having contacted the runway with the engines seems increasingly probable.

[Evan]

Here you have the URL to see the photos in full resolution:

https://scontent-dfw5-1.xx.fbcdn.net...2c&oe=5EEC69AA

https://scontent-dfw5-1.xx.fbcdn.net...1c&oe=5EEDAC91

They do look kind of shredded on the bottom (could be the low resolution). If this was from ground contact, this is just insane.

Maybe a gear collapse and they got airborne again?

[Evan]

Evan that's not just dirty engines.

I don't think it's just 'dirty engines'. I wonder if it's due to oil leakage. Do you think composites contacting with an asphalt runway would leave those black marks? Do you think they would attempt a gear-up landing without advising ATC? Without holding to work the problem first? Right now my head is leaning toward multiple engine failure due to non-standard maintenance during two months of storage. Preceded by EDP hydraulic issues. Very early blind speculation of course.

[Gabriel]

Here you have the URL to see the photos in full resolution:

https://scontent-dfw5-1.xx.fbcdn.net...2c&oe=5EEC69AA

https://scontent-dfw5-1.xx.fbcdn.net...1c&oe=5EEDAC91