Green’s Dictionary of Slang

aeroplane dress n.

also aeroplane skirt, airplane dress
[it reaches the cock pit under cock n.3 ]

a skirt or dress with a long slit reaching the groin, or one so short that when the wearer bends over, she reveals her underwear.

personal communication 2 Aug: Airplane Dress: A dress so short when the woman bends over you can see the cockpit.
C. Dodd Code 18 69: She was wearing a boob tube and an aeroplane skirt, one of those with a slit right up to the cockpit.
in C. Ebans Fashion at the Edge 274: The aeroplane dress, whose panels slide open to reveal the model’s navel.