The F-111 has variable-sweep wings that allow the pilot to fly from slow approach speeds to supersonic velocity at sea level and more than twice the speed of sound at higher altitudes. Wings angle from 16 degrees (full forward) to 72.5 degrees (full aft). Full-forward wings give the most surface area and maximum lift for short takeoff and landing. The F-111 needs no drag chute or reserve thrust to slow down after landing. The two crew members sit side-by-side in an air-conditioned, pressurized cockpit module that serves as an emergency escape vehicle and as a survival shelter on land or water. In emergencies, both crew members remain in the cockpit and an explosive cutting cord separates the cockpit module from the aircraft. The module descends by parachute. The ejected module includes a small portion of the wing fairing to stabilize it during aircraft separation. Airbags cushion impact and help keep the module afloat in water. The module can be released at any speed or altitude, even under water. For underwater escape, the airbags raise the module to the surface after it has been severed from the plane.