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Comment by sitic | Hacker News Reader

From the preliminary report:

'At 500 ft, the FDR indicates: landing gear retracted, slat/flap configuration 3, airspeed 220 knots IAS, descent rate 2000 ft/min. According to the FDR and CVR recordings several warnings and alerts such as over-speed, landing gear not down and ground proximity alerts were disregarded. The landing was undertaken with landing gears retracted. The aircraft touched the runway surface on its engines. Flight crew applied reverse engine power and initiated a braking action. Both engines scrubbed the runway at various locations causing damage to both of them. [...]'

I'm amazed that the airplane managed to become airborne again despite the engines being dragged down the runway with reverse thrust selected.

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The fact that they where around 80 knots faster than they should have been probably helped a lot. That's a heck of a lot of excess energy.

The excessive speed helped? Can you explain, I would imagine that going faster would cause more engine damage while being dragged.

But would also mean there was more energy to be converted to lift when the plane increased its attitude to take off again :)

Helped is probably the wrong word. I mean't that the aircraft had a lot of excess speed to get back into the air again, had it been at a normal approach speed you would probably have slowed down enough that it wouldn't have been possible to get it flying again.

More engine damage, probably.

But the excessive speed is what allowed the plane to lift off again.

There's a decision point past which your option to abort is no longer viable. Think of an overloaded plane attempting to take off. It may need 400 meters to brake. If the pilot continues to attempt to take off until only 200 meters of runway are left, braking is no longer an option.

In the case of the landing attempt above, reverse thrust and the very sketchy (ahem) landing configuration would typically bleed off too much speed to make a successful takeoff possible. Depending on the runway the implicit decision point might have been behind them virtually upon touchdown. With so much excess airspeed, though, while a safe stop was not possible they were still able to fly. It would have been a hell of a ride, though, and just thinking about abusing an airplane like that kind of blows my mind.

From what I can find the Airbus also requires the weight on wheels and the wheels speed sensors to have spun up before it will apply reverse thrust. Obviously the brakes also only work when the wheels are down. Auto-spoilers wouldn't deploy automatically also.

If I understand correctly does that mean they tried reversers, but they didn’t work so that’s why they initiated a go round?

The initial report indicates they did try to, but many planes won't allow reverse power unless some other indicator (landing gear down an in contact with the ground) says they're on the ground.

So maybe they'll go to idle but won't reverse, because reverse while in the air would be bad.

Fun fact, the Shuttle Training Aircraft actually used reverse thrust in the air to simulate the (probably terrifying) rate of descent of the real thing: https://en.wikipedia.org/wiki/Shuttle_Training_Aircraft

Pilot here, for anyone confused about the comment... some aircraft reach a speed where it is near a stall and cannot create a positive climb gradient when it touches down. Generally increasing angle of attack (angle the wings are with respect to the airflow) produces more lift. This works until a point is reached where the aircraft stalls (slow speed or high AOA, there is a curve). Many aircraft land near this airspeed, it produces a nice landing. But if you are faster than this airspeed, you can still pull up and create more angle of attack, create more lift, and take back off. So if you are landing fast you can easily pull up. This is exaggerated in fighter aircraft where we land at speeds that are faster than the stall threshold and a drastic pull up at landing can almost always cause a climb.

The pilot was reportedly well seasoned. I have my doubts about the quality of the report given the incredible mishandling of the situation.

"Imran Narejo, an official of the PIA Pilots Association, said Gul was a seasoned pilot with 18,000 hours of experience including over 4,000 hours in the A320."

https://english.kyodonews.net/news/2020/05/9616e4079ce1-at-l...

The report corroborates the witness, video, ADS-B, and ATC recordings we had hours after the crash. It adds more details we couldn’t determine at that time, but otherwise it looks to be quite accurate

In Pakistan, there is a culture of becoming overconfident and ignorant of the rules in the airline industry as the pilots age. This was also noted by the Aviation minister when he presented the PIA crash report to the assembly. It should be noted that two of the previous large crashes involving an Airblue and a Bhoja airplane were both concluded to be pilot error with the report pointing to overconfidence and negative attitude in cockpit, in addition to lack of regards for regulations for air safety and lack of training as well.

While I have no doubt this is true of Pakistan, it is true of many people who gain experience in a culture regardless of their age.

A while back some US Air Force pilots landed a B-1 bomber on Diego Garcia. The entire flight and the landing was flawless, other than the part where they landed with the gear in the retracted position. The report on the incidents finding was they simply went right past the item on the checklist like it never happened.

This is indicative of a systemic culture of rule breaking. This is common in all government run systems. "The system is too arduous, doesn't reflect the 'real world.' We know better than the system, we know what really matters." Eventually you have a bunch of John Waynes playing fast and loose with the rules, eventually they become emboldened, and since the government is famously bad at policing itself, these attitudes are pervasive.

This happens at the highest levels, even. Consider Hillary Clinton and the communication of classified (and information that should have been considered classified regardless of markings) via her primary email server. It's a pervasive culture of rule breaking.

>This is common in all government run systems.

I do not believe all government systems result in systemic rule breaking but only those do that do not provide an reasonable way to get things done within the rules/regulatory framework.

>This is common in all government run systems

No, that is not at all true. There are lots of government run systems, like the health care systems in most developed countries, that are just fine. The problem with Pakistan is it has a highly corrupt culture in general and in government in particular. That is no doubt why so many of the airline pilots were able to get hired without a legal licence.

Your general claim and the fact that you bring up Hillary Clinton as an example makes me think that you believe in the crackpot libertarian view that modern societies would be vastly better if we basically got rid of the government except for a few, narrow areas.

> crackpot libertarian view that modern societies

Which group, government or 'crackpot libertarians', were responsible for more deaths in the last century? I'll wait. I'm sure if you ask those in Iraq, they'd vastly prefer the US Government was more libertarian (or any NATO government, really). I understand wanting to trade blood for convenience, as long as it's not your blood.

Oh dear, you are making the argument that if it is very bad to be wrong in one irrational way, that makes it just fine to be wrong in another irrational way. Wouldn't it be better to be just, you know, right?

Ignorant of ... lowering the landing gears to land? It's just astonishing.

Gear up landings are one of the most common insurance claims for aircraft. It’s more common than you might think, even with experienced pilots.

Is there any kind of indicator in the cockpit to remind the pilot? A light? A voice (like the stall voice), that says, "Hey doofus, you're descending and close to landing, so LOWER THE GEAR!"

I’m not a pilot, but I think there’s a “too low” warning

Most airplanes have a "too slow" warning as well, e.g. a speed at which the gear ought to be down because there isn't any other reason to be going so slow except to be landing. The speed also factors into gear retraction, e.g. you are not going fast enough to fly, so gear retraction will not be actuated even if commanded.

There is. Some planes beep, others literally play a warning "too low, gear, too low, gear" in the cockpit and headsets.

But gear up landings don't happen in a normal stable approach in nice weather. Gear up landings happen when something else is going on taking all the pilots' attention. Like in this incident they were too high, too fast and descending too quickly. That causes a lot of other warnings and distractions, so they completely didn't hear the gear warning.

A friend of mine that years ago (pre-F-18) was a carrier-rated Navy fighter pilot had, after he got out, flown a Mooney for a couple decades. His wife also a pilot. He always went down the checklist verbally, every time. One time on approach he said: “Gear down. Three in the green.” meaning gear down and locked indicator on all three wheels. His wife said: “You do not have three in the green.”

The human brain is a funny thing. It will convince you of things that are not there just out of habit.

Yeah - checklists can become almost a chant, more music than informational.

"Pointing and calling" (https://en.wikipedia.org/wiki/Pointing_and_calling) appears to address this.

When I cross a road I usually quickly look two or three times to check traffic, even when it's one-way. This way, I make sure that even if I'm in a hurry, I'll likely take a look at least once at each side.

In this case, this video linked elsewhere in this thread described this happening here:

https://www.youtube.com/watch?v=zO5rXxJRmf4&t=5m48s

(I think this is meant to be an accurate simulation of the same type of aircraft under the same conditions.)

The current top comment in this thread also quotes the investigator report for this crash as saying

> According to the FDR and CVR recordings several warnings and alerts such as over-speed, landing gear not down and ground proximity alerts were disregarded.

So, yep. Although in the simulation, at least, this particular one is not a voice alert but is an annoying bell (with details of the reasons for the alert available elsewhere in the cockpit).

You're not wrong at all, and there is. It's just surprisingly easy to filter it out. If something new or non-standard is happening (ATC gave you an unusual approach, there's a traffic conflict, etc) you WILL start filtering out the less important information such as the screech of a gear horn or some other in-your-face indicator right through touchdown.

The thing about flying an aircraft is while it's 90% boring monotony, takeoff, approach and landing are all extremely time sensitive operations. It's easy to become cognitively saturated or to "get behind the aircraft". You can only go forward and you're going really fast so everything has a deadline.

The best description would be like when you were learning to drive and you merged onto a highway the first time. Lots going on, can't slow down, just have to commit and try to keep up.

It gets really easy to miss something like that. I've not missed the landing gear - but something goes a bit sideways and you are out of practice - things get skipped.

I've, for example, left the carb heat on when I had to go around. The hot summer air, combined with a C152 at max load, made for a hair raising takeoff. At 500' or so, the instructor casually asked if I was going to turn off the carb heat, which improves engine performance quite a bit.

Figure I'll fly 30 or so hours this year. The normal workflows get rusty, which is why checklists are such a thing.

When someone does a belly up landing, what usually ends up being the expensive part is the prop smacking the tarmac, the engine must be rebuilt.

This is what it looks like from the inside. Notice the beep that the pilot... missed. https://www.youtube.com/watch?v=-K4QHpVXtxI

There is different between that an hearing an audible warning annoying the shit out of you saying “Too low. Gear. Too low. Gear.”

It's pretty common.

I don't fly retractable gear aircraft, but I did spend several months exclusively flying a Citabria. On my first flight back in a more typical Cessna 172, I went through the downwind, base, and final legs as usual.

After landing and getting the plane stopped, I turned to my instructor and commented that the landing sight picture seemed a lot steeper than what I had remembered.

He smiled and pointed to the flap switch, which I had completely forgotten about. The Citabria doesn't have flaps.

Normalization of Deviance.

https://en.wikipedia.org/wiki/Normalization_of_deviance