Half the German pilots hum "Über den Wolken, muß die Freiheit wohl grenzenlos sein" after Rainhard May. This chap offered us many fine songs, several about the feelings of an aviator.
For myself, what little bit of Belgianness I have prefers the "Marche des Parachutistes"
And may I be allowed to also remember the "Roll over the barrell" popular with RAF pilots while their Luftwaffe counterparts sang "Rosamunde" to the exact same notes?