The following notes offer brief explanations of various aspects of the missions.
Combat Mission Only combat missions counted for completion of a tour. In order to be considered a combat mission the aircraft was required to fly over enemy held territory. Early on (July 1943) this meant crossing the English Channel into France, Belgium or the Netherlands. As the war progressed and the Allies moved across Europe the line was moved closer to Germany. If an aircraft aborted its mission and returned to base before crossing the line, no credit for a combat mission was given to that crew.
Aborts Almost every mission had crews aborting for some reason. Usually it was caused by an aircraft malfunction– an engine, oxygen system, fuel system. Sometimes a crew member became ill or unconscious. Other times it was weather related - unable to find the formation in thick clouds, extreme cold. A legal abort occurred when an aircraft went up as a spare to the formation and was not required and thus sent back.
Formations When flying on a mission, the aircraft were arranged into
formations. A division was made up of wings and wings were made up of groups. The group was the most autonomous unit. The group would have a lead, low and high squadron. Generally each squadron would contain two elements of 3 aircraft each.The first element flew in front of the second. The element had a lead, right wing and left wing aircraft
Le-2-3 The position in the formation was designated by 3 part code. First the squadron (Le, Hi, Lo) then the element (1, 2) and finally the element position (1, 2, 3 representing lead, right wing, left wing)