Revetment (aircraft)

A revetment, in military aviation, is a parking area for one or more aircraft that is surrounded by blast walls on three sides.

A blast pen was a specially constructed E-shaped double bay at British Royal Air Force (RAF) Second World War fighter stations, being either 150 ft (46 m) or 190 ft (58 m) wide and 80 ft (24 m) front-to-back, accommodating aircraft for safe-keeping against bomb blasts and shrapnel during air-attacks.

Although the pens were open to the sky, the projecting sidewalls preserved the aircraft from all lateral damage, with 12 in (300 mm) thick, 9 ft (2.7 m)-high concrete centres and banked-up earth on either side, forming a roughly triangular section 18 ft (5.5 m) wide at their base.

The longer spine section behind the parking areas usually encloses a narrow corridor for aircrew and servicing personnel to employ as an air raid shelter.

Examples may seen at the present Kenley Aerodrome and at North Weald Airfield, although some pens have had their second bay removed, becoming U-shaped rather than E-shaped.