The following video shows what may have caused the crash of a National Air Cargo Boeing 747-400 shortly after take off from Bagram Airfield, in Afghanistan, on Apr. 29.
As we reported on our first article on the accident, there are rumours that radio frequency monitors listened a crew report according to which the load had shifted just prior to the crash.
A sudden and violent shift of the CG (Center of Gravity) during initial climb, might have induced the impressive nose high attitude that is clearly visible in the shocking video recorded by a car dash camera.
At that speed and altitude, the aircrew could do nothing to recover the situation.
The animation below points towards the engine stall as the root cause of the crash; however, the wings stalled (they would stall even if the engines were working properly) and the aircraft almost fell from the sky like a stone.
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The engines stalled……Ignorant media strikes again.
Agreed, if you don’t know what you’re talking about, please refrain from talking about it. Of course, that never stops people.
Engines can and do suffer from compressor stall.
The wings stalled… ignorant commenter. You can hear the engines screaming before impact.
With the airplane at such an abnormally high nose up attitude it’s possible that the flow of air into one or more engines was inhibited. This causes the flow of air going backwards through the compressor to momentarily stop or even reverse, however the compressor itself doesn’t stop rotating. The engine will momentarily lose power, sometimes you will hear a popping sound and flame will sometimes come out the front of the engine. Occasionally a severe enough compressor stall can cause a flame-out.
It’s more likely here that the load shifted causing the plane to go nose up. The compressor stall(s) were secondary effects. Unlike a fighter plane the intakes on a 747 are not designed to take in air at a high angle of attack like this plane experienced.
Then why, when the aircraft is still on the ground, the engines do not rise due to lack of air flow but work and push the aircraft forward?
Terrible :/
I am now dumber having seen that…
Engines don’t stall, wings do. Idiot.
Actually, engines stall. More correctly, they suffer compressor stalls when airflow at the air intake is disrupted.
Here you can find a description of that kind of stall:
https://theaviationist.com/2011/08/22/flameout/
Wrong, engines can have compressor stalls, which this plane would have been vulnerable to in that vector.
Would just one vehicle be enough to cause a critical change in the CG?
30,000 pounds, which is roughly the weight of an MRAP, would indeed be enough, particularly the load was already toward the aft end of the CG envelope. I don’t know where it was for this aircraft, but I ran some numbers and found that in some cases, as little as 1 vehicle shifting only 6 feet was enough to throw it out of limitations. With a CG load right in the middle of the envelope, 15-20 feet could.