Helicopter deck
A helicopter deck is a helicopter pad
Helipad is a common abbreviation for helicopter landing pad, a landing area for helicopters. While helicopters are able to operate on a variety of relatively flat surfaces, a fabricated helipad provides a clearly marked hard surface away from obstacles where a helicopter can safely...

 on the deck
Deck (ship)
A deck is a permanent covering over a compartment or a hull of a ship. On a boat or ship, the primary deck is the horizontal structure which forms the 'roof' for the hull, which both strengthens the hull and serves as the primary working surface...

 of a ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

, usually located on the stern
The stern is the rear or aft-most part of a ship or boat, technically defined as the area built up over the sternpost, extending upwards from the counter rail to the taffrail. The stern lies opposite of the bow, the foremost part of a ship. Originally, the term only referred to the aft port section...

 and always clear of obstacles that would prove hazardous to a helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

 landing. In the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

, it is commonly and properly referred to as the flight deck
Flight deck
The flight deck of an aircraft carrier is the surface from which its aircraft take off and land, essentially a miniature airfield at sea. On smaller naval ships which do not have aviation as a primary mission, the landing area for helicopters and other VTOL aircraft is also referred to as the...


In the Royal Navy
Fleet Air Arm
The Fleet Air Arm is the branch of the British Royal Navy responsible for the operation of naval aircraft. The Fleet Air Arm currently operates the AgustaWestland Merlin, Westland Sea King and Westland Lynx helicopters...

, 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
Royal Canadian Navy
The history of the Royal Canadian Navy goes back to 1910, when the naval force was created as the Naval Service of Canada and renamed a year later by King George V. The Royal Canadian Navy is one of the three environmental commands of the Canadian Forces...

 and was called "Beartrap
Beartrap (helicopter device)
The beartrap is the Canadian name of a device invented for smaller warships, like frigates and destroyers, that carry helicopters. While not essential to enable embarked helicopters to operate from small escort vessels, it enables them to operate in a wider range of weather conditions.In the...

". 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
Light airborne multi-purpose system
Light Airborne Multi-Purpose System is the United States Navy's program that developed manned helicopters that assist the surface fleet in anti-submarine warfare.*SH-2 Seasprite *SH-60 Seahawk...

 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 film The Hunt for Red October
The Hunt for Red October (film)
The Hunt for Red October is a 1990 thriller film based on the novel of the same name by Tom Clancy. It was directed by John McTiernan and stars Sean Connery as Captain Marko Ramius and Alec Baldwin as Jack Ryan...

, when Jack Ryan
Jack Ryan (Tom Clancy)
John Patrick "Jack" Ryan, Sr. is a fictional character created by Tom Clancy who appears in many of his novels.-Backstory:Born in 1950, Ryan's background is established in Patriot Games and Red Rabbit. His father was Emmet William Ryan , a police homicide lieutenant in Baltimore, and World War II...

 is flown out to a submarine by helicopter. Ryan is lowered to the submarine, but brushes the officer charged with trying to hook him who receives a minor injury.

Coaxial rotor
Coaxial rotor
Coaxial rotors are a pair of helicopter rotors mounted one above the other on concentric shafts, with the same axis of rotation, but that turn in opposite directions...

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

Marine and Offshore Helicopter decks onboard offshore oil platforms and Ships are typically regulated by the rules defined within CAP 437, which defines standards for the design and marking, and lighting of Marine/offshore Helicopter decks, and is produced by the Civil Aviation Authority
Civil Aviation Authority
This is a list of national and supra-national civil aviation authorities.-See also:* Air route authority between the United States and the People's Republic of China* National Transportation Safety Board -External links:****...

. The Largest Marine Heli decks will accommodate the Boeing CH-47 Chinook , which requires a D value of 30m, and has a weight of 21.3t. More typical for vessels would be decks that will accommodate the Sikorsky S92 with a D value of 21m and 11.9t.
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