Air brake

Air brakes were starship components designed for use in an atmosphere. It was considered dangerous to leave them engaged while in hyperspace; leaving them on would result in a ship rumbling and creaking, with worse to follow should a pilot forget to disable them. In the year 19 BBY, fledgling pilot Trace Martez flew the Silver Angel — a modified Nebula-class freighter she built from spare parts — for the first time. En route in hyperspace to the planet Kessel, Martez forgot to disengage the freighter's air brakes after emerging from the skies of the planet Coruscant but later remembered to disengage them after noticing her freighter's rumbling and creaking.

Text and facts from the “Air brake” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.