Cargo Crash at Bagram

[Lonewolf_50]

Good memories, was your "not with the gear down" referring to runaway trim? If so, a question: weight-on-wheel switch interaction with trim actuators?

[Iron Duck]

In other words we shouldn't rule out the possibility this aircraft may have had no issues with loading at all, but may have had an unexpected instability in roll from the moment it got airborne.

This is very interesting. As I understand it the 747 is positively stable when normally configured. It's been described in this thread as having benign handling, and D.P. Davies certainly enjoyed it, although he was describing the B741, whereas the B744 has a different wing.

Apart from an abnormally rear CG, what would cause uncontrollable lateral instability in a B744?

I'm reminded of video of a TU-154 Dutch rolling. I'd always thought Dutch roll was characteristic of swept wing aircraft at speed and altitude; I remember Brian Trubshaw (or Roland Beamont) describing switching off the yaw damper in the cruise in a VC10 and the phugoid soon taking it to nearly 90% of bank.

Would a B744 Dutch roll to this extent in T/O configuration if for some reason its yaw dampers (if it has them) were inactive? I've been PAX many times on B744 and watched it slowly and gently wag its wings in the cruise; something I've never seen on A346, for example.

[mickjoebill]

I raised the question of a starboard wing drop and have studied the video a few more times .

These cameras have a wide field of view and there is tremendous curvilinear distortion, particularly in the corners and edges. Of course it can be analyzed with knowledge of the camera's focal length, plate scale etc. But it is not simple.

The lamp post at 2.43 gives a clue to the lens distortion.

These days it is very simple to create a lens map by shooting a chart and applying the corrections with software. In this case a map of this camera could be made if the vehicle was parked square on to a brick wall.

If the original was recorded in HD there is far more detail available than what we are looking at.

[I.R.PIRATE]

You don't think a CG shift aft would involve increased instability in all axes and specifically once the airspeed has decayed to such an extent?

[Clear_Prop]

LiveryMan:

Interesting you should ask that question. Only a few posts before I suggested something. What a coincidence!

[Good memories]

Lonewolf, I was referring to Teldorserious comment as he was one of the first ones to comment on the extended gear. If you make a tactical departure you retract the gear . If you have a load shift you are probably fighting the nose up pitch and forget the gear.

I feel sorry for these colleagues. They were flying in the **** creeks of this world. I was very fortunate to change from companies like that and worse to a legacy carrier.

By the way I like your critical comments.

[roulishollandais]

I'm reminded of video of a TU-154 Dutch rolling. I'd always thought Dutch roll was characteristic of swept wing aircraft at speed and altitude; I remember Brian Trubshaw (or Roland Beamont) describing switching off the yaw damper in the cruise in a VC10 and the phugoid soon taking it to nearly 90% of bank.

Would a B744 Dutch roll to this extent in T/O configuration if for some reason its yaw dampers (if it has them) were inactive?

It does not looks like a Dutch Roll. The roll seems controled. Machinbird explained the method used after sudden pitch up (post #95).

[Airclues]

I have no idea as to why the aircraft stalled. However, I might have some insight into the roll.

In April 1976 I was briefed on 747 airtest stalling by Ed Hartz, a Boeing test pilot. He warned that any rudder input, or engine asymmetry, at the point of the stall could cause a rapid roll rate which could not be corrected by aileron input.

[rgbrock1]

Layman question again:

Could a severe enough cargo shift, IF this is the causal affect, also compromise rear flight control integrity?

[Lonewolf_50]

Good memories: thank you, sir.
Airclues: again, thanks for the insights.

RG: If I understand your question correctly, your question regards the possibility of things moving on the inside of the hull that might cause damage to control linkage or to various electro/hydro/mechanical connections to the flight control system that controls the horizontal stab and /or elevators?

I think that someone addressed that a few pages back, let me check for a link.
EDIT:
Here were some points on what happens when the load shifts, with the last one asserting damage to a particular sub assembly.

http://www.pprune.org/rumours-news/5...ml#post7826977
http://www.pprune.org/rumours-news/5...ml#post7827272
http://www.pprune.org/rumours-news/5...ml#post7827523
http://www.pprune.org/rumours-news/5...ml#post7825392
http://www.pprune.org/rumours-news/5...ml#post7824299

Not sure if that has been answered, but someone else does seem to think that the possibility is there. I don't know the physical layout of the tail sub systems and linkages, so I can't comment.

[Teldorserious]

I will just add that if 50,000 posts later we find it was a cargo shift, it changes nothing. Pilots still need to preflight the load.

That said, I have to ponder if the slats and flaps were retracted instread of the gear. I don't know enough about the aircraft to ponder this, but slat retractions have caused stalls before.

[Intruder]

Pilots may preflight the load, but they can't catch all the defects. The pilot's preflight is only a last-minute check of the obvious. It is the loadmaster's responsibility to ensure all the technical aspects of the load are complete.

It is extremely unlikely that the flaps were retracted instead of the gear. Besides being WAY out of the habit pattern, the FLAPS 1 gate makes it damnear impossible to select the flaps UP inadvertently.

[JPJP]

deSitter -

"but there is surely a "cowboy climb" to get up and out of Dodge as fast as possible."

There is nothing "cowboy" about a V2+15 Max Power climb. It's a common procedure at some airports. Refer to the Noise abatement procedure at KSNA (Orange County).

[awblain]

Initial right roll? Hard to say.

From the video, I can't see any good horizon to decide whether there's an initial roll. As it comes into view, it appears to be flying straight, although it's hard to be sure as the dashcam vehicle is turning at that point.

From the point that the aircraft comes into view, it rolls to the left - significantly, since the road bears round more gently to the right, and yet the aircraft still stays fixed with respect to the vehicle antenna - but I can't see any way from the video to say whether this is from an initial right roll or from the wings being level.

[exeng]

Teldorserious

That said, I have to ponder if the slats and flaps were retracted instread of the gear

Even if they were (which I very much doubt) such an action would not lead to the very high pitch angles seen before the final 'departure'.

[henra]

Originally Posted by exeng

Even if they were (which I very much doubt) such an action would not lead to the very high pitch angles seen before the final 'departure'.

+1
Back in the Seventies Lufthansa lost one of their first 747s by taking of w/o Slats/Flaps properly set. Consequence was that the aircraft never really gained altitude before crashing.

The overall loss of lift will be so much bigger than any potential Pitch Up moment that the Aircraft will probably start to settle immediately instead of continuing to climb at an insane deck angle until finally running out of energy as we saw in the vids of this accident.
In this case the aircraft gained signifcant altitude for the position over the runway especially considering a high TOW. It must have had a high lift coefficient up to the point where it ran out of airspeed.

From what can be seen on the video I really see only two general mechanisms that seem to fit:
- CG too far aft (for whatever reason)
- Tail Control Surfaces deflection (for whatever reason).

I would be very surprised if it wasn't one of those two.

That said, wrt to the exact reason for either a CG problem or a control surface problem I see simply no way how this can be concluded from this video. I'm afraid we will have to leave this to the NTSB.

[777fly]

I thought this PPRuNe thread was 'RUMOURS and NEWS', not 'ENDLESS SPECULATION'.
This accident had a whole spectrum of possible causes: cargo shift, total hydraulic failure, microburst, cockpit intrusion, Taliban attack, alien death ray, etc, etc. The DFDR and CVR will reveal everything very soon; the speculation in this thread is tedious and unprofessional.

[Hacker15e]

The planks as used in the picture look dodgy,,It is more common to have several long planks stacked in alternating directions. For this applications It would have been better to have used wooden-beams, at least 6 x 6

When you say "the picture", are you referring to the shots of the MRAPs loaded on Atlas, or on shots taken on the specific National 744 in question here?

[Clear_Prop]

777fly:

It's a forum. Home to speculators and scowling nitpickers alike. The BS is tedious at times but if its that bad you can block the site in your browser settings!

[broadreach]

Hacker, I believe he was referring to the two pics Machaca posted in Post #352. The operator is not identified as National or anyone else. Including Atlas, at least in that post.