"nooneimportant" wrote

i can see the tug push would be a lot cheaper

Not really if you consider the number of tugs required at the
major hubs where perhaps 10 or more flights are pushing at the
same time and the fact that each tug requires a trained and
qualified tug operator whose union contract does not permit him
to perform any other function. If a particular flight is delayed
for a couple of minutes waiting for a last minute passenger, the
tug and operator are still tied-up where a lone signal man (who is
still required even with a tug) can easily move about the departing
a/c and provide power-back signals to the next one ready to go.

Each flightcrew must receive power-back training and it is only FAA
approved at specific gates at specific airports. The power-back is
terminated only by the use of forward thrust, the use of brakes tends
to set the aircraft on its tail.

Bob Moore
ATP B-727 (lots of power-backs)
PanAm (retired)