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wjcandee
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Re: PIA A320 (flight PK8303) crashes in Karachi

Sun May 24, 2020 11:54 pm

889091 wrote:
Were they running late? Was the cockpit crew about to time out?

They crashed in good weather right in the middle of the day. I am trying to understand why they chose to press on, even though they were coming in hot and high...


You know what, it doesn't matter why. I'm not being mean, I'm saying that there's really no excuse for this conduct. It isn't the Captain's authority, absent a true emergency, to violate the company rule that requires a stabilized approach. I know that Sky Gods do it, but they shouldn't. Because it's not up to them to take away the significant blanket of safety that this rule provides. 99 percent of the time it isn't necessary, but this accident will probably end up being an example of why it exists. A passenger expects to have the safety provided by that rule, specifically that the crew will have everything completely set-up and minimal issues and minimal distractions loooong prior to landing, and an omg-it's-so-boring uneventful and safe landing. High workload situations will necessarily-occasionally lead to something like this, especially if the tower or aircraft throw something else at you while you're already in the high-workload situation, and there's just no explanation or excuse for unnecessarily-inflicting it on yourself and those stuck in the little shiny tube with you. The WN at LGA, WN's Howard Peterson going off the end and into a gas station in Burbank ("My fault, my fault, my fault...there goes my career."), and on and on and on. There's a reason it's a hard and inflexible rule -- because when it's disobeyed it opens the door to incidents like this.

That these pilots were oblivious to the ding-ding-ding-ding that you can hear in the tower tape is an indication of exactly why they should have never put themselves in this situation in the first place. And it should be (but probably won't be) a cautionary tale for all.

And not for nothin', ten billion hours of PIC time or not, the complete lack of awareness of (or just complete mismanagement of) the aircraft's energy state from before the accident sequence all the way through it is more than a little disconcerting. Awareness of and ability to manage the aircraft's energy state is a key component of airmanship -- and a key component of safety -- and here these guys for whatever reason (incompetence, distractions, whatever) got it deadly-wrong.

I don't mean to keep repeating this, but if I'm sitting in the back, it's not up to the guys in front (unless it's an emergency) to make me an involuntary participant in (and possible victim of) their knowing decision to do things differently and less-safely than the Company requires. It's not their right or place, and while I have a lot of empathy for a guy like Peterson, that you are willing to do this once should be the last time you fly anybody but your lonesome self in an airplane -- because you have basically shown yourself willing to break the sacred trust that you have with your passengers.

The CVR here is going to be one for the ages.
Last edited by wjcandee on Mon May 25, 2020 12:11 am, edited 5 times in total.
 
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Starlionblue
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Re: PIA A320 (flight PK8303) crashes in Karachi

Sun May 24, 2020 11:59 pm

Bambel wrote:
Regarding the extended gear before the crash: what happens if the gear is in its up position and all hydraulic circuits get depressurized?




The gear would stay up and locked. You'd have to use emergency gear extension to release the uplocks.

tax1k wrote:
This may be a stupid question, but I’m assuming that the runway in a mountainous part of the world is higher relative to sea level meaning air is less dense and longer stopping times on runway. Did that play a role here? Do FBW warnings correct for that?


Karachi is on the ocean. The elevation of the airport is about 100 feet. Either way, warnings are based on radar altimetry, so height above ground.

And they are not "FBW warnings".
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
prebennorholm
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 12:12 am

AirlineCritic wrote:
Those dark marks are not just scraping, they are either oil/hydraylic fluid, or burn marks from the leaks and parts from the engine burning away.

I think the marks are just scrapings. If I'm not mistaken, then those outer shells of those engine nacelles are made of CFRP (carbon fibre). Under the paint they are black as coal.
Always keep your number of landings equal to your number of take-offs
 
o0OOO0oChris
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 12:12 am

Starlionblue wrote:
Bambel wrote:
Regarding the extended gear before the crash: what happens if the gear is in its up position and all hydraulic circuits get depressurized?

The gear would stay up and locked. You'd have to use emergency gear extension to release the uplocks.

As the RAT was deployed, the emergency gear extension should have very probably been used right?

And if they used the emergency gear extension, the gear doors will not close again, creating even more drag?

The final moment videos are not clear enough to see if geardoors where open or not.
 
LHA320
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 12:13 am

oliverrowen wrote:
A few folks have mentioned the A320 260kt gear-down refusal programming...so what if:

1) Since lowering the gear is both difficult to forget and an effective means of shedding airspeed, perhaps the crew DID drop the gear early in the descent, but did so above 260kts. Amidst the chaos of trying to get the plane onto its goideslope, is it possible they attributed the warnings to something else? Maybe the chime was already going off when they tried to lower the gear. They would have also had to miss the indicator lights, but if a lot was going on, it's possible, and is potentially more likely than forgetting about it entirely.

2) When the plane touched down (on the engines), it would have taken some time to sort out what was happening since they "knew" the gear was down, explaining the seemingly-long and repeated markings on the runway (2,500 feet is about 5 seconds at 275kts). Who knows, maybe the initial engine touchdown didn't feel all that different to the actual wheels touching down? Or maybe they thought the gear had failed.

3) It seems hard to fathom, but if the aircraft were somehow still north of 260kts when it lifted off again, the gear would remain up (with the crew still believing it was down), while all of their faculties were being utilized to figure out what had just happened and what systems were failing.

4) As the aircraft lost speed, the gear would have actually deployed (for the first time), without being further commanded to do so by the crew, thus possibly explaining why they dropped the gear on the second attempt when airspeed was such a precious commodity.

Note that while I have read this thread in its entirety, I am not a pilot. I am just an enthusiast that has lurked on this forum for many years. I am sure that many of my assumptions are incorrect and I apologize in advance.

Sent from my SM-G965U1 using Tapatalk


The main issue with your explanation is, that the gear would have lowered itself as soon as their airspeed dropped below 260 knots. The gear lever stays down when gear down is selected, so the aircraft puts down the gear automatically as selected on the lever after speed is reduced. I honestly don't think that they flew above 260 knots during the whole first approach. But I'm not jumping on conclusions here..
Last edited by LHA320 on Mon May 25, 2020 12:16 am, edited 1 time in total.
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Starlionblue
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 12:49 am

o0OOO0oChris wrote:
Starlionblue wrote:
Bambel wrote:
Regarding the extended gear before the crash: what happens if the gear is in its up position and all hydraulic circuits get depressurized?

The gear would stay up and locked. You'd have to use emergency gear extension to release the uplocks.

As the RAT was deployed, the emergency gear extension should have very probably been used right?

And if they used the emergency gear extension, the gear doors will not close again, creating even more drag?

The final moment videos are not clear enough to see if geardoors where open or not.


Yes, that is correct. The gear doors only retract if you have hydraulic pressure.

I don't know which hydraulic system runs the gear on the A320, but since they seem to have lost both engines it is a bit of a moot point in this case.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
WNbob
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 12:52 am

This would be funny if it didn't end in tragedy.

REALL? forgot to deploy the wheels?
 
Saintor
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 1:33 am

WNbob wrote:
This would be funny if it didn't end in tragedy.

REALL? forgot to deploy the wheels?



IMO, we can't rule out that the PF did request the gear down but it was rejected because the airplane was always doing >260kts. It is unlikely because you don't need a light or chime to tell you that the gear is down, and it wouldn't excuse much... still when you are committed for the next seconds and hoping for the best, it can't be crossed out at this point. Unless someone has info on speed when over the runway.... if they were able to scrap 1000 ft of runway and become airborne again, this must have been an hell of a ride.
 
LTC8K6
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 1:50 am

Saintor wrote:
WNbob wrote:
This would be funny if it didn't end in tragedy.

REALL? forgot to deploy the wheels?



IMO, we can't rule out that the PF did request the gear down but it was rejected because the airplane was always doing >260kts. It is unlikely because you don't need a light or chime to tell you that the gear is down, and it wouldn't excuse much... still when you are committed for the next seconds and hoping for the best, it can't be crossed out at this point. Unless someone has info on speed when over the runway.... if they were able to scrap 1000 ft of runway and become airborne again, this must have been an hell of a ride.


For whatever reason, the ADS-B data from the plane does not appear to have the velocity or position data present.
 
F9Animal
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 1:52 am

What are the chances that Pakistan tries to sweep this under the carpet? Isn't the airline government owned? For some reason, I suspect we may never get the full story.

As others mentioned, the if the plane is at 260 or above, the gear won't come down. I wonder if the alarm could he silenced with pushing in the master caution?
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LTC8K6
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 1:54 am

This aircraft is tracked via MLAT, which means it does not broadcast position information via ADS-B. Flightradar24’s position data for MLAT tracked flights is calculated by the time difference of signal arrival to four receivers. If fewer than four receivers see the aircraft, position data cannot be calculated, thus limiting the positional data available for this flight. Altitude data is broadcast and altitude data was received from PK8303.

FR24
 
LTC8K6
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 1:57 am

F9Animal wrote:
What are the chances that Pakistan tries to sweep this under the carpet? Isn't the airline government owned? For some reason, I suspect we may never get the full story.

As others mentioned, the if the plane is at 260 or above, the gear won't come down. I wonder if the alarm could he silenced with pushing in the master caution?


It's too late for that.

Plus Airbus isn't going to sit still for it if they try to blame the aircraft.
 
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Aesma
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 2:12 am

Well they can blame the pilots and then do nothing to improve the situation at the airline/country.

Remember the report of the Airblue Flight 202 crash : https://en.wikipedia.org/wiki/Airblue_F ... estigation

The report issued by Pakistan's Civil Aviation Authority in November 2011 cited a lack of professionalism in the cockpit crew along with poor weather as primary factors in the crash. In particular, the report noted that the captain ignored or did not properly respond to a multitude of Air Traffic Control directives and automated terrain warning systems. The report also claimed that the first officer passively accepted the captain's actions, after the captain on multiple occasions took a "harsh, snobbish and contrary" tone with the first officer and "berated" him.

The report concluded that the crash was a Controlled Flight into Terrain accident, in which aircrew failed to display sufficient judgment and professional skills in a self-created unsafe environment. In their determination to land in inclement weather, they committed serious violations of procedures and breaches of flying discipline, which put the aircraft in an unsafe condition over dangerous terrain at low altitude.


I can imagine this report looking very similar (without the weather and the terrain, of course).
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Saintor
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 2:43 am

Another belly landing where engines location made all the difference....
https://en.wikipedia.org/wiki/Mal%C3%A9v_Flight_262
 
VSMUT
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 5:52 am

LHA320 wrote:
oliverrowen wrote:
A few folks have mentioned the A320 260kt gear-down refusal programming...so what if:

1) Since lowering the gear is both difficult to forget and an effective means of shedding airspeed, perhaps the crew DID drop the gear early in the descent, but did so above 260kts. Amidst the chaos of trying to get the plane onto its goideslope, is it possible they attributed the warnings to something else? Maybe the chime was already going off when they tried to lower the gear. They would have also had to miss the indicator lights, but if a lot was going on, it's possible, and is potentially more likely than forgetting about it entirely.

2) When the plane touched down (on the engines), it would have taken some time to sort out what was happening since they "knew" the gear was down, explaining the seemingly-long and repeated markings on the runway (2,500 feet is about 5 seconds at 275kts). Who knows, maybe the initial engine touchdown didn't feel all that different to the actual wheels touching down? Or maybe they thought the gear had failed.

3) It seems hard to fathom, but if the aircraft were somehow still north of 260kts when it lifted off again, the gear would remain up (with the crew still believing it was down), while all of their faculties were being utilized to figure out what had just happened and what systems were failing.

4) As the aircraft lost speed, the gear would have actually deployed (for the first time), without being further commanded to do so by the crew, thus possibly explaining why they dropped the gear on the second attempt when airspeed was such a precious commodity.

Note that while I have read this thread in its entirety, I am not a pilot. I am just an enthusiast that has lurked on this forum for many years. I am sure that many of my assumptions are incorrect and I apologize in advance.

Sent from my SM-G965U1 using Tapatalk


The main issue with your explanation is, that the gear would have lowered itself as soon as their airspeed dropped below 260 knots. The gear lever stays down when gear down is selected, so the aircraft puts down the gear automatically as selected on the lever after speed is reduced. I honestly don't think that they flew above 260 knots during the whole first approach. But I'm not jumping on conclusions here..


It is also unlikely that you could land the aircraft at that speed and get the damage seen on the photos. The damage on the engine cowlings is to the rear, meaning they were flaring as normal. At 260 knots, you just can't flare the aircraft, it would climb.
 
PANAMsterdam
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 6:08 am

maint123 wrote:
Quite frankly the world does not care , as seen by the relatively few posts here. People here are already convinced its a piloting error, based on the fragments of evidence available.


Well i do care and the reason I haven't posted in this topic is because i am an aviation enthusiast but not a pilot or air crash investigator. Everything that I could have said about this tragic event had already been said so it's no use to repeat that just to show that I am also part of this discussion.

I believe this is one of the strangest air crashes in years. A plane that -literally- lands on its engines, without bursting into flames and then being able to lift off again for a go-around? Can't remember that has ever happend.

Was there a gear issue, or was it something like LOT Polish Airlines flight 6? (The 767 that landed without gear because the electricity switch had been pulled and the pilots forgot to check that.)

Lots of unanswered questions remain, so I will keep an eye on this topic.
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airhansa
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 6:22 am

F9Animal wrote:
What are the chances that Pakistan tries to sweep this under the carpet? Isn't the airline government owned? For some reason, I suspect we may never get the full story.

As others mentioned, the if the plane is at 260 or above, the gear won't come down. I wonder if the alarm could he silenced with pushing in the master caution?


Considering the state of Pakistan, I doubt that the international community would even get any sort of credible investigation even if the government wanted one. The expertise is non-existent in the country (and don't even get started on why the country shouldn't be allowed to have nukes).
 
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Starlionblue
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 6:27 am

F9Animal wrote:
What are the chances that Pakistan tries to sweep this under the carpet? Isn't the airline government owned? For some reason, I suspect we may never get the full story.

As others mentioned, the if the plane is at 260 or above, the gear won't come down. I wonder if the alarm could he silenced with pushing in the master caution?


Master warning, not master caution. ;)

Because it is rather important, L/G NOT DOWN is one of the few warnings where the audio cannot be cancelled by pressing the Master Warning pushbutton. You need to press the guarded EMER CANC pushbutton on the ECAM control panel.

Speculation: This might explain why the Continuous Repetitive Chime was blaring during the ATC recording.


If they were at VLE + 4kt or higher (264 kt or higher) with the gear not unlocked or the gear doors not closed, they would have gotten the OVERSPEEDwarning, which is also one the "non-cancellable" ones except with EMER CANC.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
asdf
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 6:49 am

oliverrowen wrote:
.... When the plane touched down (on the engines), it would have taken some time to sort out what was happening since they "knew" the gear was down, explaining the seemingly-long and repeated markings on the runway (2,500 feet is about 5 seconds at 275kts). Who knows, maybe the initial engine touchdown didn't feel all that different to the actual wheels touching down? Or maybe they thought the gear had failed.....


it dont add up
if the engines are on idle they need a few seconds to spool up and deliver thrust
there is no way to skid a 60.000 tons plane „a few seconds“ on engine nacels with no power applied ...
 
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Starlionblue
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 6:51 am

asdf wrote:
oliverrowen wrote:
.... When the plane touched down (on the engines), it would have taken some time to sort out what was happening since they "knew" the gear was down, explaining the seemingly-long and repeated markings on the runway (2,500 feet is about 5 seconds at 275kts). Who knows, maybe the initial engine touchdown didn't feel all that different to the actual wheels touching down? Or maybe they thought the gear had failed.....


it dont add up

if the engines are on idle they need a few seconds to spool up and deliver thrust
there is no way to skid a 60.000 tons plane „a few seconds“ on engine nacels


The full weight of the aircraft would probably not have been on the nacelles.

I can imagine a scenario where they have pushed the thrust levers to TOGA while also pulling back on the stick. The speed would have kept decaying until the engines spooled up, but they would have retained significant lift, especially as the spoilers would not have extended.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
JayinKitsap
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 7:00 am

Helicopters have ground effect lift that greatly improves hovering. I would think a wing less than 10 feet above a runway at that speed would be floating on a cushion of air, with substantially more lift than typical.
 
asdf
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 7:05 am

JayinKitsap wrote:
I would think a wing less than 10 feet above a runway at that speed would be floating on a cushion of air, with substantially more lift than typical.


ground effect alone has done that?
with TOGA applied after the first touch of the nacells to the runway?
very speculativ ...
 
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Starlionblue
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 7:11 am

JayinKitsap wrote:
Helicopters have ground effect lift that greatly improves hovering. I would think a wing less than 10 feet above a runway at that speed would be floating on a cushion of air, with substantially more lift than typical.


Absolutely. The rule of thumb is that you're in ground effect if less than half the wingspan off the ground.

After touchdown, you really need those spoilers to kill lift, or brakes won't be nearly as effective.


asdf wrote:
JayinKitsap wrote:
I would think a wing less than 10 feet above a runway at that speed would be floating on a cushion of air, with substantially more lift than typical.


ground effect alone has done that?
with TOGA applied after the first touch of the nacells to the runway?
very speculativ ...


We don't know when TOGA was set. It might have been set before touchdown. Either way, you could easily "float" for longer than it takes the engines to spool up, especially since the gear was up which would reduce drag dramatically.
Last edited by Starlionblue on Mon May 25, 2020 7:36 am, edited 1 time in total.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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Carlos01
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 7:14 am

PANAMsterdam wrote:
maint123 wrote:
I believe this is one of the strangest air crashes in years. A plane that -literally- lands on its engines, without bursting into flames and then being able to lift off again for a go-around? Can't remember that has ever happend. .


Not exactly the same (belly landing - not on engine pods) but the Malev flight 262 did this 20 years ago, went around, and landed safely:

https://en.wikipedia.org/wiki/Mal%C3%A9v_Flight_262
 
lalib
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 8:00 am

Being a Pakistani lived most of my time abroad I am embarrassed by the lack of transparency in the the country in all respect.

There is an arrogance that people in authority exhibit which is completely unfounded.

I hesitate in flying domestically and would never fly Pia internationally.

If the Govt had any balls they should shut the airline down for good and create a new company and outsource everything to QR or EK taking a percentage of the profits. This is an opportune time to do this.

Having an airline as a matter of National pride means nothing when safety of people lives are compromised.
 
VV
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 9:23 am

Who is examining the black boxes?
 
peterinlisbon
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 9:32 am

I think it´s more likely that they forgot to lower the gear. If they decided to go around because they were too high or too fast then the first thing they would do is increase thrust and start to pull back to climb. Then they would put up the gear and this takes several seconds to complete and for the landing gear doors to close. If the reason for the go around was excess height or speed, then the plane would have had no problem climbing as soon as they commanded it. There are marks on the runway from the nacelles scraping along the ground for several hundred meters and no evidence of the gear being even partially down or in transit.

Regarding the alarm in the cockpit, it´s possible that they came in knowing that they were high or fast and confused the flap overspeed warning for the gear up warning.
 
JayinKitsap
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 9:59 am

Starlionblue wrote:
JayinKitsap wrote:
Helicopters have ground effect lift that greatly improves hovering. I would think a wing less than 10 feet above a runway at that speed would be floating on a cushion of air, with substantially more lift than typical.


Absolutely. The rule of thumb is that you're in ground effect if less than half the wingspan off the ground.

After touchdown, you really need those spoilers to kill lift, or brakes won't be nearly as effective.


asdf wrote:
JayinKitsap wrote:
I would think a wing less than 10 feet above a runway at that speed would be floating on a cushion of air, with substantially more lift than typical.


ground effect alone has done that?
with TOGA applied after the first touch of the nacells to the runway?
very speculativ ...


We don't know when TOGA was set. It might have been set before touchdown. Either way, you could easily "float" for longer than it takes the engines to spool up, especially since the gear was up which would reduce drag dramatically.


I would think with just a bit of flare there would be lots of lift, compare the relatively minor damage to the cowling to the total abuse of the nose wheel in the Jetblue turned wheel landing. The pilot pulled a wheelie as long as possible, still minimized the nose loading yet the gear was turned into smoke and fire. If full weight was on the engines there would have been a 'yard sale' down the runway - oil pump here, lube pump there, half an alternator a little later. The casing would be ovalled sufficient that the blades would contact. The grinding would be quite effective brakes, losing enough speed it would make engine thrust sufficient, at the same time the blades would be flying.

https://www.youtube.com/watch?v=epKrA8KjYvg

Starlionblue - I've been up several times in a 2 person glider (a long time ago), probably a 60 foot wingspan. At almost no speed by the tow plane we were air borne, well before the tow plane, gliding about 10 feet above the runway. Needed far more speed to get sufficient lift once off the ground. The ground effect seems to be a log or a power function, high ground effects when close, not worth calculating at about the half wingspan height.
 
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mnaseeh
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 10:15 am

Crash location: https://twitter.com/ZarbeKaleemi/status/1263816418333732864

Looking at the photo in the above tweet, I wonder if they would have had better chances of survival had they chosen runway 25R.

It seems to be the "closer" runway, with fewer obstacles in the path. Perhaps they would have at least cleared the airport boundary fence and had a clear area to touchdown?

p.s. Hindsight is always 20/20.
Last edited by mnaseeh on Mon May 25, 2020 10:28 am, edited 1 time in total.
 
lalib
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 10:18 am

VV wrote:
Who is examining the black boxes?

https://www.thenews.com.pk/

Main headline. Airbus sending a team to Karachi today.
 
Boavida
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 11:14 am

I read on airlive.net that the engines made contact with the runway 3 times and that the pilots ignored 3 warnings.

Sources in the PCAA had said the plane’s engines first made contact with the ground at the 4,500-feet marker, followed a second time at the 5,500-feet marker, and a third time at the 7,000-feet marker.



Image

Source: https://www.airlive.net/breaking-pilots ... tc-report/
 
mxaxai
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 11:41 am

oliverrowen wrote:
A few folks have mentioned the A320 260kt gear-down refusal programming...so what if:

1) Since lowering the gear is both difficult to forget and an effective means of shedding airspeed, perhaps the crew DID drop the gear early in the descent, but did so above 260kts. Amidst the chaos of trying to get the plane onto its goideslope, is it possible they attributed the warnings to something else? Maybe the chime was already going off when they tried to lower the gear. They would have also had to miss the indicator lights, but if a lot was going on, it's possible, and is potentially more likely than forgetting about it entirely.

Saintor wrote:
IMO, we can't rule out that the PF did request the gear down but it was rejected because the airplane was always doing >260kts. It is unlikely because you don't need a light or chime to tell you that the gear is down, and it wouldn't excuse much... still when you are committed for the next seconds and hoping for the best, it can't be crossed out at this point. Unless someone has info on speed when over the runway.... if they were able to scrap 1000 ft of runway and become airborne again, this must have been an hell of a ride.

If I understood some of the earlier posts correctly, the gear will come down once speed drops under 260kts and the gear lever is in the "down" position. I am 100% sure that the aircraft was much slower than that over the runway; you're so far away from normal landing speeds that no sane pilot will even attempt to land. You can't even extend flaps at >230kts.

Question for StarlionBlue (or other pilots): The A320 TCDS state V_LE = 280 kts (max speed with gear extended), V_LO = 250 kts (max speed to lower gear). https://www.easa.europa.eu/documents/ty ... a/easaa064
Is the 260kts for a different Airbus model, or does your company simply have different limits?

What seems far more likely is that the aircraft was screaming multiple warnings at them, so they either ignored them as faulty or missed the one relating to the gear. In the A320 at Tallinn, the safety pilot in the jumpseat started reading the ECAM and PFD messages out loud after the first impact, so that the instructor could focus on flying. In a regular flight, that would be the job of the pilot monitoring (either captain or FO).
Seven seconds later, the safety pilot started to read loudly the ECAM display: “So we have flaps lock, flight control law, left right elevator fault, maximum speed 320, manual pitch trim use, do not use speed brakes”.
At 15:07:44 the instructor commanded the safety pilot and the student to change their seats.
The instructor asked “what is the heading of the runway”, safety pilot replied “262” and changed the heading in the FMS.
The safety pilot declared to the tower: “Tallinn Tower, we are going for runway 26” and at 15:08:28 declared engine two fire to the tower and requested for a fire brigade.
The Safety pilot informed: “Engine two is shut down”.
... to which the safety pilot stated “speed is checked, flaps three”, moving the slat/flap lever to position 3.
The safety pilot states: ”Gear is down. We don’t have engines” and starts reading the speed indication from the LH PFD to the instructor. At 15:09:56 “Speed 150”, at 15:10:00 “Speed 130”, At 15:10:02 “Speed 120”.


I think the PIA pilots would have done better after reading this page: https://safetyfirst.airbus.com/control- ... d-landing/
 
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Starlionblue
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 12:10 pm

mxaxai wrote:

Question for StarlionBlue (or other pilots): The A320 TCDS state V_LE = 280 kts (max speed with gear extended), V_LO = 250 kts (max speed to lower gear). https://www.easa.europa.eu/documents/ty ... a/easaa064
Is the 260kts for a different Airbus model, or does your company simply have different limits?


We are talking three different speeds:
- VLE: Max speed with gear extended.
- VLO: Max speed for gear operation.
- Speed at which the system prevents the gear from being extended.

The last speed is a system imposed safeguard, and in the case of the A330 is higher than VLE and VLO. I'd guess the same is true on the A320.

The VLE and VLO on the A330 are the same, 250kt, but the landing gear safety valve closes above 280kt, which isolates the gear from the hydraulic system that powers it. In other words, the landing gear will extend up to 280 kt, but that is above the safe speed at which to do so. I don't know the specific speed on the A320, but from previous comments am guessing 260 kt.
Last edited by Starlionblue on Mon May 25, 2020 12:20 pm, edited 2 times in total.
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 12:27 pm

If as we believe the engine coverings did scrape along the runway as they did, the pax must have been aware of a serious problem and scared and their fate delayed by the go around then crashing on the 2nd approach.
Unless the CDR shows a mechanical/electrical failure for the landing gear to be able to go down, it appears to be a massive fail of CRM, to follow checklists and decision making leading to loss of life. Some want PIA to face international sanctions but that is unlikely due to political pressures, especially with the USA. Meanwhile over 100 dead at a time when we are facing the greatest health crises in over 100 years.
 
889091
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 12:39 pm

After the 3rd scrape/bounce on the runway, would the A320 have reverted to Direct Law? Or Alternate Law?

If the former, could it be a repeat of SU1492 again, whereby they haven't really had much sim time flying the plane in Direct Law and botched the 2nd fatal approach?
 
VV
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 12:54 pm

WNbob wrote:
This would be funny if it didn't end in tragedy.

REALL? forgot to deploy the wheels?


There should be an ECAM memo "LDG GEAR DN" during landing.

In addition there are other indications about the landing gear position.
https://safetyfirst.airbus.com/app/them ... wnlock.pdf

I do not understand how the engines could touch the runway.

If it is during a go-around then the landing gear should have been extended and lock until the rate of climb is positive.
1 - smooth application of TOGA, watch pitch
2 - retract flap by one position, watch speed
3 - when the rate of climb is positive, retract landing gear.
That's what I remember, I might be mistaken.

There are too many confusing "explanations" in this thread and on the internet in general.

So far, I cannot understand how the engines can touch the runway if the pilots follow the procedure properly and read all the indicators properly.
 
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 12:55 pm

889091 wrote:
After the 3rd scrape/bounce on the runway, would the A320 have reverted to Direct Law? Or Alternate Law?

If the former, could it be a repeat of SU1492 again, whereby they haven't really had much sim time flying the plane in Direct Law and botched the 2nd fatal approach?


Bounces/scrapes have no effect on flight control law per se. The aircraft would most likely have been in Normal Law until the engines flamed out, at which point it would have reverted to Alternate Law.

Note: Modes are not the same as Laws.

On the approach, at 100 or 50ft (don't know the A320 exactly) Flare Mode becomes active. This freezes the stabiliser and changes pitch control from load factor demand ("Normal"), to elevator deflection being proportional to stick deflection ("Direct").

Once the aircraft touches down, pitch control changes from Flare Mode to Ground Mode. However, since there was no weight-on-wheels what with the gear still being retracted, I don't this transition would happen (not sure tbh).Once the go-around was initiated by setting TOGA, pitch control would go back from Flare Mode to Flight Mode.
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mxaxai
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 1:03 pm

Starlionblue wrote:
Note: Modes are not the same as Laws.

I think this page illustrates it quite well: http://www.airbusdriver.net/airbus_fltlaws.htm
 
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 1:08 pm

VV wrote:
So far, I cannot understand how the engines can touch the runway if the pilots follow the procedure properly and read all the indicators properly.


I can see your problem here - "if the pilots follow the procedure properly and read all the indicators properly.".

What are you not understanding, given that so many crashes are due to pilots failing to do just that?
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 1:26 pm

Starlionblue wrote:
What does envelope protection have to do with it? And which of the protections are you specifically talking about?


If an airplane slides over a runway on its engin cowlings with 150knts, a lot of forces act on the airplane.
in any case there is
a moment that pushes the nose down
a unclear engine performance
a unclear delay in thrust

I can not imagine that a pilot would be able to give exactly that control input that is necessary to get the plane back into the air slowly without pulling it over or leaving it on the runway for longer als possible

the bus envelope protection would still work if the gear was up, right?
what prevents the flight control computer to adjust the flight surfaces continually to lift of?
for my understanding the three interrupted scratches point on a very precise control input.
is it so far fetched that this was the work of the computers ...?
why should the logic revert to direct law at that point?
 
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 1:37 pm

asdf wrote:
Starlionblue wrote:
What does envelope protection have to do with it? And which of the protections are you specifically talking about?


If an airplane slides over a runway on its engin cowlings with 150knts, a lot of forces act on the airplane.
in any case there is
a moment that pushes the nose down
a unclear engine performance
a unclear delay in thrust

I can not imagine that a pilot would be able to give exactly that control input that is necessary to get the plane back into the air slowly without pulling it over or leaving it on the runway for longer als possible

the bus envelope protection would still work if the gear was up, right?
what prevents the flight control computer to adjust the flight surfaces continually to lift of?
for my understanding the three interrupted scratches point on a very precise control input.
is it so far fetched that this was the work of the computers ...?
why should the logic revert to direct law at that point?



Flight control computers can't decide to "continually lift-off". The computers act on pilot (or autopilot) input, with the addition of specific protections to maintain the flight envelope.

There is no flight envelope protection that prevents undesired ground contact.


As I said above, control law would not revert to Direct Law, or Alternate Law, due to the bounces/dragging alone.

Note the difference between laws and modes. When Flare Mode activates during the approach, pitch control goes from load factor demand to proportional deflection. The latter is equivalent to what Direct Law gives you (in pitch only mind you), but the aircraft is still in Normal Law. The Airbus Control Laws summary linked above is excellent.


Speculation follows:

A pilot who is understandably rather stressed by the situation might well push for TOGA and just hold full backstick. Which could lead to the aircraft becoming airborne in ground effect, slowing down because the engines haven't spooled up yet, then coming back down again and repeating the cycle.

We don't know if the scratches are due to very precise control input. The aircraft might have just lightly bounced three times, with significant lift throughout, before climbing back out. I'll also note that you can be very precise with a FBW flight control system.
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hitower3
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 1:55 pm

Starlionblue wrote:
Yes, that is correct. The gear doors only retract if you have hydraulic pressure.

I don't know which hydraulic system runs the gear on the A320, but since they seem to have lost both engines it is a bit of a moot point in this case.


Dear Starlionblue,
The gear is operated by the GREEN hydraulic system, which is driven either by engine 1 (default), or receive pressure from the PTU with the YELLOW system.
And yes, there is no way to lift the gear up when both G and Y had systems are toast.

Best regards,
Hendric
 
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 2:01 pm

Starlionblue wrote:
Speculation follows:
A pilot who is understandably rather stressed by the situation might well push for TOGA and just hold full backstick. Which could lead to the aircraft becoming airborne in ground effect, slowing down because the engines haven't spooled up yet, then coming back down again and repeating the cycle. We don't know if the scratches are due to very precise control input. The aircraft might have just lightly bounced three times, with significant lift throughout, before climbing back out.


agree

but I suspect that a average pilot is not able to do this maneuver by pure hand flying skills ...

most would pull as hell ... and stall because no thrust ...
 
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 2:49 pm

asdf wrote:
Starlionblue wrote:
Speculation follows:
A pilot who is understandably rather stressed by the situation might well push for TOGA and just hold full backstick. Which could lead to the aircraft becoming airborne in ground effect, slowing down because the engines haven't spooled up yet, then coming back down again and repeating the cycle. We don't know if the scratches are due to very precise control input. The aircraft might have just lightly bounced three times, with significant lift throughout, before climbing back out.


agree

but I suspect that a average pilot is not able to do this maneuver by pure hand flying skills ...

most would pull as hell ... and stall because no thrust ...


The engines only take 5-6 seconds to spool up. In ground effect, you can float for quite a while. And even after a few seconds you'd have some thrust.

Lots of variables.
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A330freak
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 2:54 pm

Flightradar24 has been able to analyse extended mode S data to produce indicated Airspeed information
Image
https://www.flightradar24.com/blog/paki ... r-karachi/
 
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Aesma
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 3:04 pm

If that fall from 200kts to 150kts at 9:38:49Z is when they got the gear down (and pulled up a bit it seems) then they were gliding fine for a belly landing or might have even been able to get the gear down later, but by doing it then they doomed themselves.
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hivue
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 3:12 pm

asdf wrote:
Starlionblue wrote:
Speculation follows:
A pilot who is understandably rather stressed by the situation might well push for TOGA and just hold full backstick. Which could lead to the aircraft becoming airborne in ground effect, slowing down because the engines haven't spooled up yet, then coming back down again and repeating the cycle. We don't know if the scratches are due to very precise control input. The aircraft might have just lightly bounced three times, with significant lift throughout, before climbing back out.


agree

but I suspect that a average pilot is not able to do this maneuver by pure hand flying skills ...

most would pull as hell ... and stall because no thrust ...


The airplane was apparently in Normal Law as it climbed out after scraping the runway. The pilot could "pull as hell" all he wanted and still not be in danger of stalling.

The question that interests me is was the airplane in Normal Law (whatever mode it was in) at the time of the crash. From the various videos it does not appear that it ever stalled despite the pilot likely pulling full back stick trying to make a runway nearby in clear sight.
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CPHGuard
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 3:30 pm

A330freak wrote:
Flightradar24 has been able to analyse extended mode S data to produce indicated Airspeed information
Image
https://www.flightradar24.com/blog/paki ... r-karachi/


Since they gain both speed and altitude after the first attempt, it seems that the engines were still working to some degree at that point.

This would indicate that the loss of engine power happened after they climbed out.
 
BlueHeaven1969
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 3:30 pm

That FlightRadar24 data looks a little fishy to me. 220kts on final approach? At that speed they wouldn't even be able to extend the flaps.
 
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Re: PIA A320 (flight PK8303) crashes in Karachi

Mon May 25, 2020 3:38 pm

A Q&A worth repeating:

GalaxyFlyer wrote:
AT wrote:
What I still am baffled by is why the descent prior to the first landing was so abnormally steep. If there were a problem, surely ATC would have been informed and there would have been emergency crews at the ready. Similarly for a landing gear problem.

Any number of reasons, traffic created a delayed descent clearance, crew missed a radio call and descended late, prior ATC sector had a traffic conflict, terrain. Crews wind up high and/or fast everyday for innocent combinations of factors—it’s what you do to get back “on profile” for a stabilized approach that matters.

There's lots of innocent ways to find oneself high and hot, what really matters is what you do to get back "on profile" or do a go around when it becomes obvious that you aren't going to salvage the landing. It'll be interesting if we ever get the true CVR and FDR readouts. I suspect it won't show the crew and in turn their airline and in turn their government in a positive light, so I'm doubtful we ever will.

I've listened to the ATC and what is surprising is the calmness in the voice of PNF. Warnings going off in the pattern? No problem. Go around after knowing you've been scraping the pods on the ground? No problem. Both engines out? No problem. All very strange to me.

CPHGuard wrote:
Since they gain both speed and altitude after the first attempt, it seems that the engines were still working to some degree at that point.

This would indicate that the loss of engine power happened after they climbed out.

Yes, the theory is dragging the engines along the runway caused failure in some system needed to keep the engines running, such as oil pressure or cooling, and it would take it a bit of time for the engine to fail in that scenario.
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