The skin on the United B744 near the APU appeared to be no thicker than expected.

And I'm sure the pilots would appreciate the company effectively saying "Look, we appreciate you're good pilots (or so you think), but realistically we expect you're going to have a tail strike or 3 during your career with us, so we've taken the liberty of having extra thick tail strike protection added to our aircraft so you don't feel so bad if you give it a thump on departure. Just try not to use it too much, we can't afford too many repairs"

More than minor
 

There was more than trivial tail shell deformation, which probably explains the loose seats mentioned in ACARS. Oddly the ATSB report omits any mention of that ACARS transmission. I wonder if that's part of what they reviewed.

Bottom line seems to be a gust of cross and slight tail wind at VR combined with de-rated thrust led to some left column correction just at the commencement of rotation which in turn caused a spoiler-triggered momentary loss of lift sufficient to leave the a/c with insufficient ground clearance when rotate angle over-pitched to 4 degrees nose up. UA has now modified pilot training on their 744s from 3 degrees to 2.5 degrees of rotation to match Boeing's recommendations.

Basically a flukey wind condition just at the critical commencement of rotation was the primary cause, so I doubt that the (flying) PIC would suffer any opprobrium.

Hi Philip,

Why do you not believe the ATSB when they say that the damage was minor?

All said, it is minor damage on a 747. That structure at the back end of the aircraft is not pressurised and is not really structural. Ultimately it is an aluminium cover for the APU.

If another departing aircraft had not mentioned it to ATC the aircraft would have flown to its destination without any problems and then the defect would be picked up during the maintenance check there. (I said this earlier, I just noticed)

The ACARS that you are referring to states that there are loose floor panels not seats. Not related to the tail strike me thinks. The pax, pilots and cabin crew would have been totally oblivious to the tail strike. For the amount of damage it would have been a millisecond touch, not audible over the engine noise.

What is interesting though is if you look at the pictures that Tony G took there is not a moderate aileron input as suggested by the ATSB report. It must have been before the photos were taken. I wonder if the ATSB was aware of the existence of the photos?:D