Any aircraft can tip on it's tail if the c&g is aft enough.
Maybe some heavy cargo was going to be removed, tout de suite?
http://www.key-codes.com/images/b747_tail_tipping.jpg
Ouch.
It happens to other types of aircraft, too
http://4.bp.blogspot.com/_jO8u2-d0y3...go%2Bplane.jpg