airbrake

noun2

1. •
   A brake (slowing device) that is operated pneumatically (by air pressure).

   • The powerful airbrake of the truck quickly brought it to a stop.
2. •
   A movable control surface that extends to increase drag without affecting lift (unlike a spoiler); a device that provides aerodynamic braking.

   • The BAe 146 and Fokker 100's tailcone-mounted airbrakes allow them to slow down quickly for steep approaches without experiencing the lift degradation seen with spoiler-only aircraft.