Helicopter deck

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A U.S. Navy SH-60 Sea Hawk helicopter of Helicopter Anti-submarine Squadron Light 46 (HSL-46), prepares to lift off from the flight deck of the USN Arleigh Burke Class (Flight IIA) Guided Missile Destroyer, USS Mason.
A U.S. Navy SH-60 Sea Hawk helicopter of Helicopter Anti-submarine Squadron Light 46 (HSL-46), prepares to lift off from the flight deck of the USN Arleigh Burke Class (Flight IIA) Guided Missile Destroyer, USS Mason.

A helicopter deck (or helo deck) is a helicopter pad on the deck of a ship, usually located on the stern and always clear of obstacles that would prove hazardous to a helicopter landing. In the U.S. Navy it is commonly and properly referred to as the flight deck. In the Royal Navy, landing on is usually achieved by lining up slightly astern and on the port quarter, as the ship steams into the wind and the aircraft captain slides across and over the deck.

Shipboard landing for some helicopters is assisted though use of a haul-down device that involves attachment of a cable to a probe on the bottom of the aircraft prior to landing. Tension is maintained on the cable as the helicopter descends, assisting the pilot with accurate positioning of the aircraft on the deck; once on deck locking beams close on the probe, locking the aircraft to the flight deck. This device was pioneered by the Royal Canadian Navy and was called "Beartrap". The U.S. Navy implementation of this device, based on Beartrap, is called the "RAST" system (for Recovery Assist, Secure and Traverse) and is an integral part of the LAMPS MK III (SH-60B) weapons system.

A secondary purpose of the haul-down device is to equalize electrostatic potential between the helicopter and ship. The whirling rotor blades of a helicopter can cause large charges to build up on the airframe, large enough to cause injury to shipboard personnel should they touch any part of the helicopter as it approaches the deck. This was depicted in the 1990 motion picture The Hunt for Red October. In the film, CIA analyst Jack Ryan (Alec Baldwin) is flown out to the submarine Dallas in a helicopter. With no place to land, Ryan has to be lowered to the Dallas, but brushes the officer charged with trying to hook him. The officer is shocked and receives a minor injury. Ryan releases himself from the harness and is rescued by divers.

Coaxial rotor helicopters in flight are highly resistant to side-winds, which makes them suitable for shipboard use, even without a rope-pulley landing system.

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