Horrific 747 Crash - Bagram, Afghanistan

[eightyknots]

yeah to be honest, they showed that on the news last night without any sort of warning, not really something I wanted to see without knowing - esp while just learning... that is going to be burned into my mind for a long time. I will be very anxious to see the report on this one, it would be an interesting one for Air Crash Investigations to do a piece on.

There would be few worthwhile pieces left to examine after all the fuel from the 747 burned at once.

 

 

[dutchroll]

I might add that it also crashed with the gear still down, which you can clearly see just before impact. The first thing you do in a heavy jet (as with virtually any retractable aircraft), is when you get a positive rate of climb, call for the gear up.

 

So we have

 

a) enormous and unusual pitch angle straight after takeoff (way above what you could achieve to peg the speed even if the plane was empty)

 

b) they never got the gear up

 

c) it stalled at an altitude and attitude from which recovery would be impossible

 

To me, this all points towards a catastrophic nose-up pitching moment on or just after rotate/liftoff. My best guess is that they were so preoccupied with struggling to control the pitch-up, that they never actually got around to putting the gear lever up.

 

 

[Dieselten]

And putting the gear up wouldn't have made any difference anyway. That's seven professional airmen who aren't going home to their families any more and one tough, rugged and dependable airframe gone - forever. The airframe is just hardware, but the seven lives are irreplaceable to their family and friends. RIP.

 

 

[eightyknots]

I might add that it also crashed with the gear still down, which you can clearly see just before impact. The first thing you do in a heavy jet (as with virtually any retractable aircraft), is when you get a positive rate of climb, call for the gear up.So we have

 

a) enormous and unusual pitch angle straight after takeoff (way above what you could achieve to peg the speed even if the plane was empty)

 

b) they never got the gear up

 

c) it stalled at an altitude and attitude from which recovery would be impossible

 

To me, this all points towards a catastrophic nose-up pitching moment on or just after rotate/liftoff. My best guess is that they were so preoccupied with struggling to control the pitch-up, that they never actually got around to putting the gear lever up.

The impact with the gear up would have been only delayed by a few milliseconds.

 

 

[dutchroll]

Yes I agree. I guess what I was saying is that the gear position is another clue that something really serious happened immediately after rotate which preoccupied their thoughts and actions.

 

 

[Guest ozzie]

In the States a few years back a King Air that was overloaded and aft CoG due to overweight passengers stalled just after take off when the gear was raised, the rear ward retracting nose gear took the aircraft's CoG even more aft. The aircraft crashed. Investigation revealed that the aircraft may have been recovered if the gear was lowered again.(air crash investigations have covered this one)

 

Hard to tell from the dashcam footage what angle the 747 achieved but there is some report that it may have been approaching 80deg vertical. It would have taken several thousand feet to recover from that. If you could get the CoG back somewhere normal.

 

Another consideration is if the load had moved rearward enough to damage the rear pressure bulkhead and maybe the control system for the tail had been damaged as they run behind the bulkhead. There were a few photos a couple years ago going around that showed a large very heavy drilling head that punched out of it's box and penetrated the bulkhead narrowly missing the control run. Wrote the aircraft off but everyone survived unlike the poor souls in this accident.

 

 

[motzartmerv]

You sure it was a king air? I thought it was an ATR or dash 8.

 

 

[octave]

Interesting video about weight and balance, simulations at 16:00

 

 

 

[turboplanner]

The cargo was wheeled cargo

Australian tenders call for standardised lashing points for military vehicles; I can't remember whether a capacity is specified but assume it would be.

However, during inspection, I've never been asked to do a lashing strain test or provide calculations.

 

One possibility is that a lashing point weld may have broken and set off a chain reaction - and at least there would be similar vehicles still existing which could be tested.

 

 

[pudestcon]

I'm only a lowly Thruster flyer, so what would I know, but looking at the video I see the aircraft looking like it has an extreme rear CoG - uncontrollable probably, which bears out the premise of cargo shifting rearward. Why then after the stall does it not drop tail first? By the time it impacts the ground the nose is well down.

 

Pud

 

 

[Head in the clouds]

I'm only a lowly Thruster flyer, so what would I know, but looking at the video I see the aircraft looking like it has an extreme rear CoG - uncontrollable probably, which bears out the premise of cargo shifting rearward. Why then after the stall does it not drop tail first? By the time it impacts the ground the nose is well down.Pud

That's a really good observation Pud.

As I imagine it - consider the direction of the drag force at the stall, up and back, so I think that direction of resistance would effectively pull the tail up as the plane begins to fall, even though the maximum form drag might be ahead of the CG at that time - which might make it appear more logical that it should fall tail first.

 

Once the nose is down then the form drag would stop the plane falling as fast as gravity, so the loose cargo inside would come crashing forward giving the aircraft a nose heavy condition. Not a nice place to be I imagine.

 

I have a friend who is a former 747 cargo Captain and a bit 'in the know' about this incident, he mentioned that the cargo included 5x 12 tonne trucks ...

 

 

[Guest ozzie]

You sure it was a king air? I thought it was an ATR or dash 8.

aircraft was a Beechcraft 1900d later variant of the King Air. operated by Air Midwest as flight 5481. This crash was caused by overweight and aft CoG combined with incorrect control system adjustment to the elevators. The aircraft pitched up even further when the gear was raised.

 

 

[Admin]

Would the flight recorders withstand such an intense fireball as shown in the accident video?...I would assume they would have to have been made to withstand the maximum heat that an accident could generate.

 

 

[facthunter]

They are meant to stand a lot of heat for a while Ian. Ozzie, retracting the gear will reduce drag but that drag is low down so will add to the pitch up. same as when the gear is lowered it usually causes a pitch down.

 

The rear pressure bulkhead failed in a 747 in Japan and control was lost. I think it was the elevators affected. This plane appeared tail heavy but it would be worthwhile to examine the control positions from the visuals. The stabiliser (Horizontal) has a lot of authority, (as well as the elevators) but as the speed drops , less and less.. Nev

 

 

[motzartmerv]

I don't think deconstructing the crash is going to help just yet, until the facts are in. The tail heavy thing doesnt have the effect of just holding the tail down, its all about aerodynamic loads and couples, the sea saw thought process only works in a static environment. The Aft C of G (if thats what caused the problem) may have meant that the elevator (stabilizer) could not over come the pitching moment until it stalled,theres two different things going on, one when its flying and subject to the aerodynamic forces, and the second when it goes rocketing through the critical angle. This aeroplane was deeply stalled, not just a little bit stalled. While its one of the most horrible things ive seen, its still an amazing bit of vision, and it highlights the incredible amount of power those engines must have to allow the thing to get into that position at such low altitude. I feel for the families of the crew that would have such a graphic reminder of their loved ones final moments. The only consolation i guess, that there was no suffering.

 

 

[Billzilla]

747's are pretty insensitive to a few tonnes here or there but 12 tonnes would be very difficult to combat if it moved down towards the tail. They were dead just after they left the ground. :(

 

 

[Owi]

I heard an interesting theory - the pilots may have punched the wrong numbers into the computer when doing their takeoff calculations and so the plane over-rotated after V1. Or the computer malfunctioned. It could be that the PIC realised too late what was happening and was too late to switch to manual control to recover. That could explain the fact that it nearly righted itself before hitting the ground, as opposed to hitting the ground tail-first which it should have if there was a significant load shift to the aft.

 

 

[Billzilla]

I heard an interesting theory - the pilots may have punched the wrong numbers into the computer when doing their takeoff calculations and so the plane over-rotated after V1. Or the computer malfunctioned. It could be that the PIC realised too late what was happening and was too late to switch to manual control to recover. That could explain the fact that it nearly righted itself before hitting the ground, as opposed to hitting the ground tail-first which it should have if there was a significant load shift to the aft.

Not much of that is true sorry.

 

On the -400's the pilots enter in the weights of the fuel and ZFW (Zero Fuel Weight) into the FMS (Flight Management System, by Honeywell) and from that combined weight and airport location to work out the various V-speeds that are then confirmed manually out of the books by the other pilot.

 

The only automatics used to takeoff on the 747's is the autothrottle and that just goes for either a target EPR (Engine Pressure ratio) or %N1 (fan speed, in the case of GE engines)

 

The reason it 'righted itself' was still due to a very rearwards Cog, I suspect.

 

Best wait until the official reports come out anyway.

 

 

[Guest Maj Millard]

No doubt the panel would have been lighting up like a Xmas tree at that high alpha and obvious low airspeed toward the top, stick-shaker and all probabily. Hard to imagine somebody didn't try to push the nose down, which leads me to think they couldn't for some reason............time will tell on this unfortunate incident.............................Maj...

 

 

[Billzilla]

No doubt the panel would have been lighting up like a Xmas tree at that high alpha and obvious low airspeed toward the top, stick-shaker and all probabily. Hard to imagine somebody didn't try to push the nose down, which leads me to think they couldn't for some reason............time will tell on this unfortunate incident.............................Maj...

They would have been pushing the controls through the clocks with all their strength.

The Alpha Floor warning would have been blaring away for sure though.

 

 

[ben87r]

Not something that pushing the nose down could avoid if the W+B is out beyond elevator authority. As for "righting" itself, are they not designed to have the dragline in a stalled condition rearward to aid with recovery? i had thought that once stalled it would have helped the nose to lower and slowly aid recovery

 

 

[turboplanner]

If you have a substantial tonnage moving to the rear you have to start including balance weights, kinetic energy, thrust vectors etc in addition to control surfaces and wing lift - a lot of things can be in play at once which are not normally in the equation.

 

 

[Billzilla]

Not something that pushing the nose down could avoid if the W+B is out beyond elevator authority. As for "righting" itself, are they not designed to have the dragline in a stalled condition rearward to aid with recovery? i had thought that once stalled it would have helped the nose to lower and slowly aid recovery

Not really sure what you mean with most of that, but an aircraft with a CoG that far back would have no longitudinal dynamic stability and would never be able to achieve stable flight, no matter what control inputs were made.

 

As usual, it's best until we can read the official report so we have an idea as to what went on. Until then speculation probably won't help.

 

 

[Ultralights]

i dont think loading was an issue, apparently the aircraft had already flown 1 sector with the load it had when it crashed, it stopped over in bagram to refuel only

 

 

[turboplanner]

You could be right UL, but it could also be that a lashing snapped on the takeoff, presenting a fresh problem - pure speculation I know.