After a mid air collision, Caldwell managed to get his damaged aeroplane back down.. Here is a passage that explains it better.
In September 1918 Caldwell’s quick thinking and resourcefulness saved him after he was involved in a mid-air collision during air combat. Struck by another S.E.5a from his squadron at 16,000 feet, the impact seriously damaged his wing struts and sent his aircraft into a semi-flat spin. In an oft-repeated story, it is said that after falling several thousand feet, Caldwell stepped out onto the lower wing in an attempt to control the stricken aircraft’s descent. Holding a wing strut with his left hand, and controlling the joystick with his right, he managed to crash land behind British lines, leaping to safety seconds before the plane hit the ground. In fact Caldwell himself chose to correct the story, though even by his account it is an exciting story of disaster averted by quick thinking:
You refer to the account of my standing on the wing of a SE5 aircraft which had been damaged in a collision. Afraid this is not correct. I think either 'Taffy' Jones, who wrote some war books after WWI, or perhaps Springs may have given this wrong story, as writers sometimes did to embellish situations. What did happen was that I found that I could get the machine under some control by putting my left foot on the right rudder and leaning out to the right as far as I could. All this performance took about 8,000 feet and then I had to lose further height to keep some control and crashed a short distance behind our lines. Aeroplane no good, but pilot cut lip and plenty bruises … Anyone conversant with the controls of a sensitive aeroplane would know that to leave the rudder alone would be disastrous. So much for that episode.