Why do plane groups split on intercept missions?
Remember; if you assign an airgroup to intercept, only those planes capable of executing an ATA attack will split off (and they WILL split off) individually. If you want to split a couple of planes off, select the airgroup and then go to the formation editor and split off a few planes, then assign them to an Intercept mission. Remember that an air group will loiter at its optimum fuel-saving altitude.