Extended Operational and Trade Vocabulary

Helicopter Operations on Ships glossary

The shipboard helicopter-operations vocabulary: helideck structural and fire-protection rules, AFFF deluge systems, the FAA heliport design circulars, and the named helicopter types (EH101, EC225) used in offshore and SAR work. Grounds each term in the helideck standard or the aircraft type it belongs to.

182 defined terms.

A

ABS Guide for Building and Classing Offshore Installations: American Bureau of Shipping rules; Chapter 4 covers helideck structural design and fire protection.
AC 150/5390-2C: FAA Advisory Circular for heliport design, including offshore platform heliports.
AFFF: Aqueous Film Forming Foam, the primary fire-fighting agent for helideck deluge systems, typically 6% concentrate.
AgustaWestland EH101: Three-engine medium-heavy helicopter, military variant Merlin, civil variant AW101 used in SAR.
Air-Side: The side of helideck operations involving the aircraft, refueling, and ground handling.
Airbus EC225: Heavy twin Super Puma variant, 11.0 t MTOW, formerly common offshore, withdrawn after 2016 Turoy accident, partial return from 2018.
Airbus H160: Medium twin helicopter, 6.0 t MTOW, Fenestron tail rotor, offshore variant H160 OO.
Airbus H175: Super-medium twin, 7.8 t MTOW, 16 to 18 passenger offshore configuration, range about 300 nm.
Airbus H225: Renamed EC225 Super Puma after Airbus Helicopters rebrand 2014.
Alert State: Pre-arrival readiness condition declared on the helideck before helicopter inbound.
Amber Status Light: Helideck status light indicating limited operations or caution condition.
Anti-Icing: Engine and rotor blade systems preventing ice accretion during flight in icing conditions.
AOG: Aircraft On Ground, status indicating helicopter unserviceable at remote location.
APU: Auxiliary Power Unit, small gas turbine providing electrical and pneumatic power on ground.
AS3795: Australian Standard for offshore helicopter landing areas.
ASTM D1655: Standard Specification for Aviation Turbine Fuels, including Jet A-1.
ATPL(H): Airline Transport Pilot Licence Helicopter, highest civil helicopter pilot qualification.
Autorotation: Emergency descent technique using airflow through unpowered rotor to maintain rotor RPM.
Avincis: Spanish-based helicopter operator group, owner of Babcock MCS aviation businesses.
AW101: Leonardo three-engine heavy helicopter, used as Norwegian SAR Queen and Canadian CH-149 Cormorant.
AW139: Leonardo medium twin helicopter, 6.8 t MTOW, 15 passenger offshore standard.
AW189: Leonardo super-medium twin, 8.6 t MTOW, SAR and offshore transport variant.

B

Babcock Helicopters: UK-based offshore and emergency services helicopter operator, part of Avincis since 2024.
Beacon: Fixed AtoN, lit or unlit.
Blade Sailing: Excessive rotor blade flexing during low-RPM startup in high wind on a moving deck.
BOSIET: Basic Offshore Safety Induction and Emergency Training; OPITO standard.
Bristow: International helicopter operator providing offshore transport and UK MCA SAR services since 2015.
BST: Basic Safety Training, mandatory STCW VI/1 short course bundle for all seafarers with designated safety duties.
Bund: Containment kerb around refueling area to retain spilled fuel.

C

CAA: Civil Aviation Authority, UK regulator publishing CAP 437 and CAP 1145.
CAP 1145: UK CAA Offshore Helicopter Review published 2014 after 2012 to 2013 North Sea accidents.
CAP 437: UK CAA Standards for Offshore Helicopter Landing Areas, 9th edition, primary global reference.
CAT.POL.H: EASA Part-CAT subpart on commercial air transport helicopter operations performance.
CH-149 Cormorant: Canadian Forces designation for AW101 SAR helicopter.
CHC Helicopter: Major international offshore helicopter operator headquartered in Texas.
Chevron: Yellow perimeter markings on helideck indicating obstacle-free sector boundaries.
Chocks: Wedges placed against helicopter wheels or skids to prevent rolling on deck.
Cold Refuel: Refueling with rotors stopped and engines shut down.
Cone Strobe: White warning light atop nearby obstructions visible to approaching aircraft.
Cougar Helicopters: Canadian offshore helicopter operator serving Atlantic Canada platforms.
CRM: Crew Resource Management, training in non-technical flight crew skills.
Cyclic: Primary helicopter flight control varying rotor disc tilt.

D

D-Circle: Painted circle on helideck whose diameter equals the design D-value.
D-Value: Largest overall dimension of helicopter with rotors turning, governing helideck size.
Day Flight: Helicopter operation conducted in daylight under visual conditions.
DCP: Dry Chemical Powder, monoammonium phosphate based fire-extinguishing agent in 45 kg helideck units.
Deck Edge: Outer perimeter of helideck, marked with white edge line.
Deck Landing Officer: Officer responsible for helicopter movements on deck, often combined with HLO role.
Deck Motion: Combined pitch, roll, and heave of a vessel affecting landing limits.
Deck Offset: Difference between helideck reference point and vessel motion center.
Deluge System: Fixed foam fire-fighting system delivering AFFF at 6 L/min/m2 across helideck.
Density Altitude: Pressure altitude corrected for non-standard temperature, affecting helicopter performance.
DLAS: Deck Landing Aid System, instrumented limits for pitch, roll, and heave.
Dollies: Wheeled cradles fitted under skid helicopters to permit ground movement.
Down-Wash: Vertical air column produced by rotor blades, affecting personnel and loose deck items.
Dropped Object Survey: Inspection of overhead structures near helideck for fall hazards.
Dry Friction Test: Measurement of helideck surface friction in dry conditions, minimum 0.65 per CAP 437.

E

EASA: European Union Aviation Safety Agency, regulator for European helicopter operations.
ELT: Emergency Locator Transmitter, automatic 406 MHz distress beacon fitted to helicopters.
Engine Failure: Loss of one or more engine powerplants, governing OEI performance planning.
Era Aviation: US-based helicopter operator, predecessor of Era Group.
Era Group: US offshore helicopter operator, merged with Bristow in 2020.
ETSO C70a: European Technical Standard Order for helicopter emergency flotation equipment.

F

FAA: Federal Aviation Administration, US civil aviation regulator.
Falling Gradient 1:2: Obstacle clearance gradient applied below helideck level under CAP 437.
Falling Gradient 5:1: Maximum permissible obstacle slope rising from helideck edge in LOS.
Filter monitor: dP transmitter indicating filter element fouling on fuel and lube oil lines.
Fire Team: Trained helideck crew on standby during all helicopter movements.
Flotation Gear: Pop-out floats fitted to helicopters for emergency water landing.
FOD: Foreign Object Debris, loose items on helideck capable of being ingested by engines.
FOET: Further Offshore Emergency Training; OPITO BOSIET refresher.
Friction Coefficient: Hull to seabed grip value used in pull force calculations for refloat.
Fuel Sample: Pre-refuel jar sample checked for water, sediment, and color contamination.

G

Green Status Light: Helideck status light indicating operations may proceed.
Ground Handling: All deck activities supporting helicopter arrival, refueling, and departure.

H

H225 LP: Long Range Passenger variant of Eurocopter Super Puma, 11.0 t MTOW.
HCA: Helideck Certification Agency, UK independent helideck certifier.
Heave Limit: Maximum permissible vertical deck motion, typically 1 m for unrestricted operations.
Helicopter Landing Officer: Senior helideck role responsible for safe helicopter handling.
Helicopter Operating Company: Commercial operator providing offshore or SAR helicopter services.
Helideck: Flight deck on surface combatant sized for embarked helicopter.
Helideck Monitoring System: Sensor suite measuring deck motion, wind, and environmental envelope.
Heliservice: German offshore helicopter operator serving North Sea wind farms.
HFOM: Helicopter Fuel On-board Monitoring, accurate fuel quantity indication system.
HHO: Helicopter Hoist Operation, winching personnel without landing on deck.
HLL: Helicopter Landing Light, illumination of helideck for night operations.
HLO: Helicopter Landing Officer, certified deck officer in charge of helicopter operations.
HMS: Helideck Monitoring System.
HOC: Helicopter Operating Company.
Hot Refuel: Refueling with rotors running and passengers offloaded.
Hover-Down: SAR winching technique with helicopter in steady hover above deck or sea.
HSSC: Harmonized System of Survey and Certification under SOLAS, MARPOL, Load Lines, and BCH/IBC/IGC/BWM.
HUEBA: Helicopter Underwater Emergency Breathing Apparatus, 3 minute STASS air supply.
HUET: Helicopter Underwater Escape Training, capsized cabin egress drill.
HUMS: Health and Usage Monitoring System, vibration analysis for rotor and gearbox condition.

I

ICAO Annex 14 Vol II: International Civil Aviation Organization standard for heliport design.
ICS Guide to Helicopter/Ship Operations: International Chamber of Shipping reference, 5th edition 2008.
IFR: Instrument Flight Rules, flight by reference to instruments only.
Immersion Suit: Watertight survival suit worn by passengers and crew on offshore flights.
IMO MODU Code: International Maritime Organization Code for Mobile Offshore Drilling Units, Chapter 9 covers helideck.
IMO MSC.1/Circ.1390: Guidelines for the construction, installation, and use of ladders.

J

JAR-OPS 3: Joint Aviation Requirements for commercial helicopter operations, superseded by EASA Part-CAT.
Jet A-1: Aviation kerosene; cleanliness paramount.

K

Knots: Wind speed unit used in helideck wind reports and operational limits.

L

Lashing Points: Recessed tie-down fittings around helideck for securing parked helicopter.
Lider Aviacao: Brazilian helicopter operator serving offshore oil and gas industry.
Limited Obstacle Sector: LOS, 150 degree sector around helideck with restricted obstacle height.
Logistics Flight: Routine transport rotation moving crew, mail, or cargo to and from offshore site.
LOS: Limited Obstacle Sector.

M

MAUW: Maximum All-Up Weight, total permissible helicopter weight at takeoff.
MCA: UK Maritime and Coastguard Agency, responsible for SOSREP intervention.
MD-902: McDonnell Douglas Explorer NOTAR single-engine helicopter, EMS and offshore use.
Medium Expansion Foam: AFFF foam type producing expansion ratio 20 to 200 for helideck deluge.
MEDIVAC: Medical evacuation flight to remove casualty from offshore installation.
Merlin: AW101 military variant used by Royal Navy and other services.
MH-60T Jayhawk: US Coast Guard medium-range SAR helicopter, derivative of Sikorsky S-70.
MH-65 Dolphin: US Coast Guard short-range SAR helicopter, derivative of Eurocopter AS365.
MIST: Minimum Industry Safety Training, OPITO common safety course for offshore personnel.
Monkey Board: Elevated railing or step at helideck edge, can present obstacle to rotor disc.
MORS: Mandatory Occurrence Reporting Scheme, UK aviation safety reporting requirement.
Motion Sensor: Helideck-mounted accelerometer measuring pitch, roll, and heave.
MSC.1/Circ.1390: IMO guidelines on ladders, including those used for helideck access.
MTOM: Maximum Take-Off Mass, certified weight limit for helicopter departure.

N

NDB: Non-Directional Beacon, low-frequency radio navigation aid sometimes installed on installations.
NH90 Caiman: French Navy designation for NH90 helicopter in SAR and ASW roles.
NH90 NFH: NATO Frigate Helicopter variant for ASW/ASuW.
NHV Group: Belgian-based offshore helicopter operator serving North Sea and West Africa.
Night VFR: Visual flight rules operations conducted at night, restricted offshore.
NORSOK C-004: Norwegian standard for helicopter deck on offshore installations.
NUC Light: Not Under Command light shown by vessel during helicopter operations on deck.
NUI: Normally Unattended Installation, platform visited periodically by helicopter.

O

OAT: Outside Air Temperature, primary input to density altitude and performance calculations.
Obstacle-Free Sector: OFS, 210 degree sector around helideck free of obstacles above deck level.
OEI: One Engine Inoperative, performance condition with one powerplant failed.
OERTL: Offshore Emergency Response Team Leader, OPITO senior emergency role qualification.
OERTM: Offshore Emergency Response Team Member, OPITO basic emergency team qualification.
OFS: Obstacle Free Sector.
OIM: Offshore Installation Manager; person in charge on offshore unit.
OPITO: Offshore safety training accreditation body (BOSIET, MIST, HUET).

P

Passenger Briefing: Mandatory safety brief before helicopter boarding covering emergency equipment.
Petroleum Air Services: PAS, Egyptian helicopter operator serving Red Sea and Mediterranean.
PHI Inc: Petroleum Helicopters International, US Gulf of Mexico offshore operator.
Pitch Limit: Maximum permissible vessel pitch angle, typically 3 degrees for unrestricted operations.
PoB: Persons on Board, helicopter occupant count reported before each flight.

Q

Quadrant: Brass arc on the rudder head to which steering chains are attached.

R

Reach Air Medical Services: US-based air medical helicopter operator.
Rear Crew: Winchman and winch operator team in SAR helicopter cabin.
Refuel Hydrant: Fixed below-deck refueling point with retractable hose.
Refuel Manifold: Pressurized fuel distribution unit connecting hose to dispenser nozzle.
Resolution A.890(21): IMO Principles of Safe Manning, references HLO certification requirements.
Roll Limit: Maximum permissible vessel roll angle, typically 3 degrees for unrestricted operations.
Rotors Running Refuel: See Hot Refuel.

S

Salt Water Deluge: Helideck fire-fighting system using sea water for cooling and dilution.
SAR: Search and Rescue, governed by the 1979 SAR Convention and IAMSAR Manual.
SAR Queen: Norwegian Air Force designation for AW101 SAR helicopter.
SAR Tech: Search and Rescue Technician, Canadian Forces rear-crew specialist.
Sector Flight: Rig-to-rig hop without returning to mainland base.
Sikorsky S-76: Light-medium twin helicopter, 5.3 t MTOW, used for offshore and corporate transport.
Sikorsky S-92: Heavy twin, 12.0 t MTOW, 19 passenger, 800 km range, offshore industry workhorse.
SOLAS V/14: Convention regulation governing helicopter facilities on ships.
STASS: Short Term Air Supply System, 3 minute emergency breathing system inside HUEBA.
Stinger: Curved overboard ramp on S-lay pipelay vessels.
Strobe: High-intensity flashing light marking obstacles or helideck perimeter.
Super Puma: Family of medium-heavy Aerospatiale, Eurocopter, and Airbus helicopters including AS332 and EC225.

T

T-Value: Helideck tonnage rating, maximum permissible helicopter mass for the structure.
Tie-Down: Securing helicopter to deck using lashings to lashing points.
Turbulence: Disturbed airflow around installations affecting helicopter handling on approach.

U

Ullage: Empty space above liquid cargo in a tank.

V

VFR: Visual Flight Rules, flight by external visual reference.
VHF Marine Channel: Radio frequency used by helicopter to communicate with ship before landing.
Vortex Ring State: Aerodynamic condition during low forward speed descent where rotor enters own downwash.

W

Wave off: Cancel an approach.
Wet Friction Test: Helideck friction measurement in wet conditions, minimum 0.65 per CAP 437.
Winch Operator: SAR rear crew member controlling hoist cable and conning pilot over target.
Winch-Only Operation: Crew transfer by hoist without helicopter landing on deck.
Winchman: SAR rear crew member lowered on hoist to recover casualty.
Wind Indicator: Helideck instrument displaying real-time wind speed and direction to pilot.
Wind Sock: Fabric cone showing wind direction at helideck, illuminated at night.

X

X-band: 8 to 12 GHz radar band (9.2 to 9.5 GHz for marine radar and Racons).

Y

Yellow H: Painted helideck identification marking at deck center, 4 m high, 0.75 m stroke.

Z

Zone 1: Hazardous area classification around fuel handling on helideck.
Zone 2: Secondary hazardous area classification adjacent to Zone 1 around refueling operations.