Nothing says you can’t take off all your planes during one mission phase. Being new to this game though, I have learned that’s not a smart move … as you (Half-Track) have said and history re-affirms.
In my first full game from the current Avalon Hill Guadalcanal online campaign, I have a land based, aircraft heavy force builds with over 5 quadrons on each side. I am beginning to suspect that that is not normal and I am not as concerned about the delay of play-by-forum game due to back and forth air mission unit placement.