Common sense........lost in SOP's
glum I am assuming that you misunderstand the B737 terminology, I don't think that you would put one of the wing engines on your Tristar up to 80% N1 during pushback.
Chough
I am endebted to for finding that accident report, I did not know of the inccident but it seems to have panned out much as I predicted in post #3 but fortunately without injury to any one, but clearly the tractor driver was of the opinion that it was wise to leave the area with some haste!
Graziani
As English is clearly not your first language I will tell you that when an Englishman says that something is unwise it is a polite way of saying that it is a stupid idea. My concern is that you are more interested in if there is an SOP for this or some legislation to prohibit the practice rather than considering the physical aspects of the way the forces that the aircraft and tractor are producing will be interacting, if you had taken the time to think about this you would have been unlikely to ask the question in the first place.
On a general note I have noticed that some of the newer people in the industry have become SOP drones who are totaly convinced that if they stay on SOP and within all the rules they will be safe, they are very keen to point even the slightest non compliance with SOP without understanding the reason. These people seem to know every thing and understand nothing.