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I have been trying to go over how this could happen. The damage to the wall seems so severe that I would image even over the sound of the engine the pilot would hear and notice that they had hit a wall. Flying the plane at this point would be risking their life. The first thing that came to my mind was the only reason a pilot would risk his life is if his life was already at risk and if he had been drinking when he hit the wall he would face many year in jail I assume for putting lives at risk. In a panic says to himself the plane is damaged but I know it can still fly and takes off without a plan really but perhaps just to let the alcohol he had leave his system. I hate to speculate here on HN. This is just crazy to me and I really look forward to hearing more details as to how his happened.

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Over at http://pprune.org the suggestion is that the pilot's seat was not locked into position correctly and slid back during takeoff. This caused the pilot to pull back on the stick too early and his instinct was the push forward to keep the plane on the correct trajectory. He likely over-corrected and ended up flying 6ft off the ground at the end of the runway where the landing gear caught an antenna and the chainlink fence on top of the brick wall.

It's all speculation at this point.

Ugh, there have been Cessna deaths caused the same way. It's my least favorite failure mode to think about, since there's no obvious way to correct. In a Cessna, best you can do is release the yoke and tiptoe on to the rudders, but professional instructors have still died when this happens to them, since low altitude errors are often not correctable by the time you've lost too much altitude.

Usually there ought to be more than one locking mechanism involved, though..?

https://generalaviationnews.com/2018/03/16/failure-secure-se...

https://generalaviationnews.com/2016/10/18/seat-sliding-back...

In contrast, I can't say I've ever heard of seats in cars having this problem. Is it because plane seats are highly optimised for weight?

Could be because people don't generally drive 40 year old cars! The aircraft in the first fatal link above was manufactured in 1979 and the seat failed in 2016; the second was manufactured in 1969 and crashed in 2014.

And because it would be less likely fatal in the car, so you'd be less likely to hear of it happening.

(Less likely fatal because car collisions are less fatal due to e.g. airbags, and less likely to impact terrain since it only takes a second to undo your car seatbelt, and because there's no pitch control to have messed up.)

Pulling back on a car’s steering wheel doesn’t do anything. Also, cars have a very low stall speed.

A car's stall speed depends heavily on the car's altitude.

If your car seat slides back unexpectedly, the most likely problem will be a decreased ability to press down in the accelerator. The seat would generally slide back only under forwards acceleration. Under braking the seat would slide forward giving positive pressure onto the brake pedal.

It also diminishes your ability to brake. And if you do slide back, and the seat then locks in place, that could be serious.

You would keep steering the car, while also attempting to unlock the seatbelt. Depending on the car, you could also activate the parking brake. (In my car, it's a button on the center console, and it can be activated at high speed and will provide emergency braking.)

"Serious" is still not the same as "fatal", even if your car hits something. If your plane stalls and falls hundreds of feet, my understanding is that the fatality rate is going to approximate 100%.

My wife knows of two fatal car accidents caused by this. Don't adjust your seat whilst driving peeps, and make sure it clicked into position before you drive if you adjust it.

Wow, thanks for the info. If you happen to have links for them, I'd be curious to read more.

Mind sharing what causes the accident, does a sliding seat cause the driver to yank the steering wheel and lose control?

Also, what about adjusting the steering wheel while driving? Sounds like a similar threat.

Inability to apply enough force to the brake pedal at the right moment.

One of them was adjusting the seat whilst driving, it flew back and she swerved. The other one I understand was a seat which wasn't clicked in.

My front driver's seat adjustment is all motorized - but not the passenger seat. Originally it annoyed me (the motors are so slow to move!) but now I'm wondering if it might be an intentional safety feature - it's never "unlocked", so you won't suddenly slide away from the pedals and wheel because a part failed to latch right.

Suppose your car seat hasn’t locked. You drive, then you suddenly go up a hill, and the seat slides back. Well, fine, you hold on to the steering wheel (or not), stop, take a breath, adjust the seat, and carry on.

Suppose your plane seat hasn’t locked. You taxi around to the runway (slow and always level), then you begin the takeoff run. Already, you have some acceleration pulling back. Then you gently pull back the yoke to rotate. Now, suddenly your seat slides back. You hold onto the yoke, stall, and die. Or you let go off the yoke, and now the plane is unpiloted in the crucial take-off phase. And, note, stopping is not an option at this point.

That’s why vigorously thrashing around in your seat is part of the before-takeoff checklist (“Seat - LOCKED”).

If your car seat is electric is probably based on a worm gear which is more or less self locking.

From that thread:

https://youtu.be/t9Ugn0jq_60

Those passengers just won the lottery.

And quite probably many people living just past the end of the runway.

I've flown A380 and B747 on a commercial (Lufthansa) simulator. Both had seats which could be only moved with motors (locking in any position). Don't know how it is with B737 but I would assume the same (for this very reason).

How will the alcohol ‘leave his system’ in the 4 hours it takes to fly to Dubai from India?

Pilots would have to blow 0.0 but that doesn't mean zero evidence of alcohol. In 4 hours you can metabolise around 4 standard drinks out of your bloodstream. It's not like drugs where any trace is bad because it's illegal.

That said, I'm not sure I am on board with the explanation. It could just be that with everything going on in a cockpit it wasn't noticed.

Does reduced air pressure speed up the removal of alcohol via breathing?

If a fever can, wouldn’t alcohol do the same?

A fever is, at it’s core, an increase in metabolic rate. Your hypothalamus is telling your body that it’s temperature set point is higher than usual, and it takes energy to raise your temperature. I don’t see how a difference in air pressure would have a similar effect.

other way around - reduced air pressure is reduced oxygen, which is lower metabolism. Higher metabolism causes EtOH degradation to go more quickly. Fever is higher metabolism.

Your blood oxygenation will stay at 95-99% even while in a cabin.

Metabolism in aircraft is pretty low: you’re generally sitting idle, but I think the alcohol metabolism is still constant except the terminal metabolism.

Fever is partly metabolism, but largely reduced cooling.

I've taken an oximeter with me on flights before, and can give a data point of n=1 to say this isn't the case.

My oxygen % decreased initially with altitude until it stabilised around 90-92% (at ~10k feet, IIRC). It sat at this point for the whole flight (8 hours), with a low of 87%.

Through forced rapid deep breaths I could get it back up into the mid-high 90s, but also got light headed and funny looks.

Moving around the cabin would also raise it.

Interesting, the studies i’ve Read pegged the average reduction at 4%.

After V1, the accelerate-stop distance, the pilot is committed to continue flying.

The cargo area of most airliners is not pressurized, so the gash is not an immediate problem.

In a case like this, the pilots would want to climb to several thousand feet and evaluate the situation before landing.

Looks like the pilot did a great job once it was realized the airplane was damaged of remaining calm and flying the airplane.

Not a pilot, and not trying to be an armchair pilot, but why would he have ascended all the way to 36000 feet? Isn't there a real risk of depressurization with hull damage?

No. If there was a leak then it wouldnt pressurize properly on the way up. If it was holding pressure, it would probably keep doing so.

It totally depends. A weakened structure can hold pressurization for a while, and then suddenly (and possibly catastrophically) fail.

A famous example of this is American Airlines flight 96 (1972): https://en.wikipedia.org/wiki/American_Airlines_Flight_96

Also Japan Airlines Flight 123

I'd rather not trust my life to "probably". If there was some damage to the hull or a cargo door that could lead to failure, it's under more stress and is more of a hazard as the altitude increases.

Less stress imho. At altitude the forces on wings/structure are far less than during takeoff.

The takeoff has already happened, and a landing (of some sort) will have to happen (which also means flying near ground level).

The thing that doesn't need to happen is flying at full flight altitude when the pressure differential between the inside and outside is greatest.

Incorrect. In level flight the wings have - by definition - 1g of upward load. Regardless of speed or altitude.

Consider cabin pressure differential versus the outside ambient air.

That’s what sand worm was saying - level flight puts less stress on the wings than takeoff (where you accelerate vertically, thus have more than 1g).

Still, you don’t want to take a structurally damaged plane high up.

1g in up/down force. But thicker air means more forwards/back forces. Higher engine power = more force, regardless of G.

Engine power is a fraction of weight. Even at full thrust (which is rarely used in commercial service, even for takeoff), the engines are only capable of 0.25g or so.

One minor UX gotcha: the alarm for a pressurization problem on a 737 is not all that intuitive.

https://en.wikipedia.org/wiki/Helios_Airways_Flight_522

"probably"

To take a structurally damaged plane to altitude with that argument (if it holds pressure, it probably won’t explode) is reckless folly.

the cargo hold of a 737 is indeed pressurized https://aviation.stackexchange.com/questions/8252/are-cargo-...

@ codeisawesome If he only had a small drink he might have though a couple hours flight time is all his body needed to metabolise the alcohol to where it wouldn't be detected. Again I hate to speculate here and hope that there is a more rational explanation as to why things went the way they did. For example like captain_perl said at a certain speed the pilot is commited to take off. Ok, but why continue flying and not get enough height to turn around and land immediately? Was he following some protocol that states continue climbing then assess damage? Did air traffic tell him to proceed as planned? To the casual observer here, things don't add up. I am hoping there is some explanation but at this point something weird seems to have happened or we are missing a part of the picture. Very interesting.

You replied to the wrong comment.

Cargo is definitely pressurized. Not heated/aced, but pressurezed the same as the rest of the cabin. Everying from the skin inwards is under 5000ish feet of pressure.

It's heated above freezing too as far as I know, I've never had anything in my luggage freeze.

Heated in that the air becomes warmer as it is compressed. But not the additionally-heated air provided the main cabin. Even so, at low air density even -30 would take a while to cool the large mass of bags.

The front cargo hold is heated with engine bleed air.

V1 is the takeoff decision speed, not the accelerate-stop distance.

The accelerate stop distance is the distance it takes to accelerate to V1, reject the takeoff, and stop the aircraft. V1 is in KIAS (knots of indicated airspeed). ASD is in feet/meters.

You are correct that passing V1, the aircraft is committed to fly unless an emergency relating to controllability surfaces.

> After V1, the accelerate-stop distance, the pilot is committed to continue flying.

I'm not a pilot, but I'm 100% sure V1 means you can't safely abort the takeoff, _not_ that you're committed to the remainder of the flight.

Also, the ILS is at the end of the runway, they were surely airborne by this point (i.e. past V2), so I'm not sure why you even brought up V1 in this discussion.

In fact, I can't imagine being so low at the end of the runway. At somewhere like Midway (MDW), you'd almost certainly hit a house, at the very very least the perimeter fence.

> In a case like this, the pilots would want to climb to several thousand feet and evaluate the situation before landing.

I'm fairly certain that in an emergency situation you don't "evaluate the situation". Short of actually being unable to fly, you have to take off after V1. If there is any issue whatsoever, you alert the tower and begin to come around to do an emergency landing using "normal" emergency procedures.

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