[Mobhack]

It has no "preference" for blue troops, in fact they are less likely than reds to be chosen, it is just that when yours and theirs are both mixed into the target zone, which is a 500-199m circle round where the plane decides to attack, then there is a chance that the sky jockey will select a friendly instead of an enemy. The more blues than reds in the pick'n mix selection, the more chance it will target the friendlies.

Air strikes should be de-conflicted from friends, by at least a kilometre, and it also helps if the ingress route does not pass over friends either. Planes start to look along their flight path, and if that drops short into the friendlies, then they may select them instead.