Horiffic 747 crash at Bagram Airbase

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Southron

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Too many news sources have reported the crash. My guess...the dash cam's date hadn't been re-set properly after a battery died-that is why an incorrect date is showing.
 

davidb

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BTW...another thought comes to mind after Jay mentioned the checks and rechecks of the load securing devices. It's also possible that the load did not shift, but the load calcs were done incorrectly, whether it was input error, mislabeled load weights on a vehicle, or metric-english conversion errors. I still favor the load shift theory though... if the load was balanced wrong in the first place, it would be a fine line between the aft CG limit and the point at which the plane would have tipped back on its tail while still on the ground.

Does anyone know what that line is? Can a 747 be unbalanced to the point that it would exhibit this much loss of control in the air but not tailsit on the ground?
From what I'm reading, this was to be the second leg flown with this load on board. They were on a fuel stop at Bagram so one would have to assume the new fuel load weight and balance was incorrectly calculated to support the theory that it was out of cg range before this takeoff--unlikely IMO.

Seems it is common practice to use a tail stand during loading/unloading to prevent a possible tailsit but I doubt it would be anywhere near a 'tailsit' cg even with the cg well past the aft flight limit. A grossly aft cg would have become apparent as soon as they pushed up the power. A load shift during rotation/liftoff seems much more likely, IMO.

From one of the links posted above, they have the impact site right at the departure end of the runway. Hard to imagine a 747 reaching 1200' agl and then hitting the ground all in the distance of 12,000' from the start of their takeoff roll.
 

topspeed100

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Seems it is common practice to use a tail stand during loading/unloading to prevent a possible tailsit but I doubt it would be anywhere near a 'tailsit' cg even with the cg well past the aft flight limit. A grossly aft cg would have become apparent as soon as they pushed up the power. A load shift during rotation/liftoff seems much more likely, IMO.
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I agree...it gathered speed normally and just as they pulled the stick at the rotation they must have heard and felt that something ain't right and possibly tried to push all they had and still the plane just kept going almost vertically up. What ever moved may have also shifted the CG also to the right...there was one incident in Russia where old Tupolev had no aileron control nor elevator..and they flew and landed it by using only throttle and rudder ( also on video ).

Could the load that moved also brake linkages to tailfeathers ?
 

bmcj

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Seems it is common practice to use a tail stand during loading/unloading to prevent a possible tailsit but I doubt it would be anywhere near a 'tailsit' cg even with the cg well past the aft flight limit. A grossly aft cg would have become apparent as soon as they pushed up the power. A load shift during rotation/liftoff seems much more likely, IMO.

We used tailstands on some of our aircraft when we loaded them because the cargo was loaded from tail to nose. The DC-8 was notorious for tailsitting during loading making the stand a required step before loading or unloading. The 767 was much more tolerant of imbalance on the ground.

Agree about the aft CG showing up in the handling before takeoff.
 

DesertFlier

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I used to work as a 747 mechanic for Southern Air, another airline that charters military flights in and out of places like Afghanistan. In fact, my first fear when I heard a cargo 747 crashed in Afghanistan was that it might be one from my former employer, though it's tragic regardless of who it belongs to.

The aft cargo shift definitely seems to be the most likely cause. In a cargo 747, the vehicles would be tied down to "cookie sheets", large metal pallets. The pallets then sit on the roller trays and are moved in to place with power drive units (PDUs), then locked in place with end locks that flip up and grab the edge of the pallet. So, either the pallet came loose from the locks, or the the load came off the pallet. Unfortunately, the loadmaster was killed in the crash, but the investigation will undoubtedly find the cause.

Regardless, there's nothing the pilot could have done. In the video, you can hear the engines roaring at full power, and it looks to me like he's applying full down elevator. The stabilizer trim takes about 20 seconds to go from full up to full down, and full nose down is only -1.5 past neutral, so it's definitely too little and too late to counter a massive CG shift.

My thoughts are with the families of the deceased. If not for the ever changing winds of fortune, it might have been me or someone I know on that flight.
 

topspeed100

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I used to work as a 747 mechanic for Southern Air, another airline that charters military flights in and out of places like Afghanistan. In fact, my first fear when I heard a cargo 747 crashed in Afghanistan was that it might be one from my former employer, though it's tragic regardless of who it belongs to.

The aft cargo shift definitely seems to be the most likely cause. In a cargo 747, the vehicles would be tied down to "cookie sheets", large metal pallets. The pallets then sit on the roller trays and are moved in to place with power drive units (PDUs), then locked in place with end locks that flip up and grab the edge of the pallet. So, either the pallet came loose from the locks, or the the load came off the pallet. Unfortunately, the loadmaster was killed in the crash, but the investigation will undoubtedly find the cause.

Regardless, there's nothing the pilot could have done. In the video, you can hear the engines roaring at full power, and it looks to me like he's applying full down elevator. The stabilizer trim takes about 20 seconds to go from full up to full down, and full nose down is only -1.5 past neutral, so it's definitely too little and too late to counter a massive CG shift.

My thoughts are with the families of the deceased. If not for the ever changing winds of fortune, it might have been me or someone I know on that flight.
20 seconds is a lifetime in that situation...in usual flying that is enough but in an emergency like this it should have been oprated in a second or two. Still apparently unflyable ?
 

bmcj

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The driver of the vehicle doing the filming must have been a bit concerned, just as I would have been, watching the jet grow larger in the windshield. If you notice, not only did he stop, but he started backing up.
 

DesertFlier

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I read a couple interesting things on the very long thread on the PPRuNe forums.

The first is that the MRAPs, being exceptionally heavy, aren't simply held in place on the pallets. After the pallets are locked in to place, the vehicles are secured in to place with approximately SEVENTY 5000-pound-rated cargo straps which are locked directly in to the seat tracks (yes, even a cargo 747 has seat tracks).

The second is that this was the second leg of the flight for this load, with no cargo added or removed during the stopover. It seems strange that cargo that was secure enough for one leg would suddenly come loose during rotation on the next. Some have speculated that a large fuel upload may have moved the CG out of limits (unlikely, IMO). others have mentioned that the pilots may have used a "tactical takeoff" procedure, basically a very steep climb out to avoid possible ground fire, and that this may have exacerbated the problem. It's going to be very interesting to see what the investigation comes up with.
 

timberwolf8199

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Has anyone noted what the landing was like? If it's the same cargo it may have been jarred loose on landing but not caused the problem until TO rotation. Or shifted forward slightly causing a false W/B that became tail heavy after it shifted back into it's correct position during TO.
 
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