Until now, I thought airplanes would only attack sequentially. The simultaneous runs were a big surprise. In another game I bought five (I think - the game isn't over yet and there is no way to check until the score window comes up) attack aircraft, and they came one after the other; bomb, strafe, strafe, sometimes strafe again, and next airplane's turn.
It's not unusual to see two planes atacking at the same time , in a recent game I saw 3 allied planes atacking at the same tank , and seconds later a german plane atacking at another tank . It ' was too in a big map . It was a beatiful airstrike with 4 planes at the same time bombing the map.