Helideck

Why a ship carries a helideck

Offshore support vessels, drilling units, cruise ships and many large tankers carry a helicopter landing area for crew changes, medical evacuation, pilot transfer and, on offshore units, daily personnel movement. On a fixed platform the deck can be built for the purpose; on a ship it has to fit around the superstructure, the cranes and the masts — which is why the approach sector and the turbulence created by the ship's own structure dominate the design.

What happens during a landing

A helicopter movement is never a routine deck operation. Before the aircraft arrives, the deck is cleared and inspected for loose objects, the ship is turned to bring the wind into the required sector, and the fire fighting arrangement is set up and manned. The Helicopter Landing Officer takes charge and remains in communication with the bridge and the pilot.

The reason for the standby fire team is straightforward: a helicopter carries several hundred litres of fuel above a steel deck, and if it comes down badly there are seconds, not minutes, to act. On a well-run vessel the team is fully dressed in fire fighting outfits with breathing apparatus, hoses are run out and charged, foam monitors are aimed at the touchdown area, and the deck fire pump is running — not on standby, running — before the aircraft is on final approach.

Main components

Deck structure and surface

Sized to the largest helicopter type by its rotor diameter, the so-called D-value, which appears as a marking on the deck together with the maximum permitted weight. The surface is non-skid and slightly cambered so that fuel and water drain to the perimeter, never towards the accommodation, and the drainage leads to a safe collection point rather than over the side.

Perimeter safety net

A net around the entire deck edge to catch a person who slips. It is inspected as part of the routine deck rounds; a damaged net is a reason to suspend helicopter operations.

Fire fighting arrangement

Foam is the primary agent. Larger installations use a deck integrated fire fighting system with pop-up nozzles that flood the whole deck within seconds; smaller ones rely on monitors and hose lines with foam branch pipes. The foam concentrate stock, the discharge rate and the duration are prescribed and checked during survey. Dry powder and CO₂ extinguishers cover engine and electrical fires, and a crash box holds the tools needed to reach a trapped occupant — heavy-duty cutters, a crowbar, an axe, a harness knife.

Lighting and visual aids

Perimeter lights defining the landing area, floodlights that illuminate the deck without dazzling the pilot, a lit windsock, and status lights that tell the pilot whether the deck is cleared. On many vessels a signal lamp indicates that operations are suspended.

Motion monitoring

A ship's deck moves. Pitch, roll, heave rate and the inclination of the deck are monitored continuously, and each helicopter type has limits beyond which a landing is not permitted. The system displays the current values to the bridge and, on modern installations, transmits them to the aircraft.

Refuelling arrangement

Where helicopters are refuelled on board, the installation is separate from the ship's own fuel system, with its own filtration, water detection, bonding and earthing points, and its own sampling routine. Aviation fuel handling is treated as a distinct discipline, not as a variation of bunkering.

Regulations and survey

Helideck arrangements sit at the intersection of maritime and aviation rules. SOLAS covers the ship-side fire fighting requirements, the IMO Mobile Offshore Drilling Unit code applies to drilling units, and the aviation authorities of the flag and coastal states set the physical and lighting standards — in the North Sea the UK CAA guidance is the practical reference for most operators. Class surveys the structure, the fire fighting installation and the drainage; the aviation inspection covers markings, lighting, obstacle clearance and the operating limits.

Typical findings

• Foam concentrate past its shelf life or below the required stock — among the most common deficiencies found during inspection.
• Blocked or corroded deck drains, allowing spilled fuel to spread instead of draining to the collection point.
• Perimeter net damaged or its supports corroded, often unnoticed because nobody walks the edge.
• Lighting failures discovered at night, when it is too late; the reason lighting is tested before every planned movement.
• Crash box incomplete — tools borrowed for other work and never returned.
• Obstacle clearance compromised by newly installed aerials, lights or cargo stowed in the approach sector.

What to look for in a supplier

• Complete package capability: deck structure, non-skid surface, netting, lighting, foam system and monitoring from a coordinated design rather than assembled piecemeal.
• Certification acceptable to both class and the relevant aviation authority for the vessel's operating area.
• Foam concentrate supply and testing service, including shelf-life management.
• Training support for the landing officer and the fire team — the equipment is only as good as the crew operating it.

Practical rule from offshore operations: the deck is not ready when the equipment is present, but when the team has run out the hoses, charged the lines and confirmed the drains are clear — every single time.