The size of a helicopter landing pad, commonly abbreviated as a helipad, is dependent entirely on the type or types of helicopter making use of it. A small medevac helicopter requires much less room than a military transport helicopter, so they use differently sized helipads.
There are many different types of helipad. Civic helipads see use by medical evacuation helicopters, rescue copters and other civil service vehicles, while recreational helipads are used mainly by privately owned helicopters. Military helipads are the purview of the Army, Air Force and Navy and see use in wartime and in defense.
Measurements for a CH-58 helipad include:
- A 72x72 takeoff and landing area.
- A full-area width and length of 500 feet.
- A 101 approach-departure surface ratio.
Clearance is one of the most important criteria in determining the situation and construction of a helipad. Because the downdraft from a helicopter's active rotors can raise powerful winds, everything at the site must be secured and all vital positions protected and located at a safe distance from any descending vehicles.
Some helipads are mobile, supported on the backs of rescue vehicles, which use gyroscopic balancing and winches to create a level landing surface using their trailer area. This allows rescue and medical choppers to function even in terrain where no landing would normally be possible.