Theory
Based on the photo in post 5.
There appear to be 3 sets of skid marks visible in the photo:
1: opposed cresents just in front of the engine;
2: large radius arc splitting to 2 tracks in the foreground;
3: (possibly) behind the inboard main gear wheels.
Marks #1 from tug which doesn't move much but is rotated ~90° right during the "manoeuvre".
Mark #2 traces the arc of the nose gear, radius = nose gear to tug centre of rotation, as the a/c rotates to its left. Track splits into two when the shear pin lets go and gear steers left.
Mark #3 caused when crew apply brake (parking brake?) and also indicates a/c rotation to its left.
So, the ballet started with the tug in position indicated by marks #1 and the a/c further back and with a heading maybe +30° to +90° compared to its final heading. Towbar probably close to a/c axis.
No.2 engine goes to high power. A/c brakes are off. Tug brakes are on. No.1 engine may not have started yet or is spooling up or at idle. Monster resulting torque is enough to skid the nose gear to the a/c's left. Shear pin goes when the nose gear steering angle limit is reached. Crew apply brakes. Tug driver ****s his pants. Tug contacts inlet and rattles around against it until No.2 is shut down.
Last edited by SyEng; 4th May 2013 at 22:52.
Reason: spelling