Flying units attacking rear ?

[liga]

I have looked in old thread and find something usefull ... but still I have some dubt:

How is the best way to have high probabilty that flying units really attacj the enemies rear ?

It seems that my flyer are better in doing that if:

1) they start just in the middle of the field and not in the rear and

2) if I give them teh order attack instead of hold-and-attck (that I was us ti prefer becouse often some squads in the rear move up and left the leaders alone)

... si that true or are only strange coincidence ?

thks
Liga