Offshore Operations

 

The term “offshore operations” is used to describe situations where not only a part of the flight takes place over large bodies of water but when most of the flight, including the main objectives, are to be completed away from dry land. Driven by industry demand, the use of helicopters in offshore operations has increased greatly in the recent years. Because of their VTOL and hover capabilities, helicopters are often used to support:

• Construction and maintenance of offshore wind farms;
• Construction and maintenance of offshore oil and gas platforms;
• Various ship operations;
• Various authorities (e.g. coast guard).

The main offshore tasks performed by helicopters are:

• Moving people to and from their workplaces on offshore facilities and vessels;
• Equipment inspection;
• Freight transportation;
• Emergency evacuation;
• Search and rescue missions (e.g. it is often faster to send a helicopter to reach a person that has fallen overboard than to use the vessel they have fallen from).

Safety Risks

There are a number of risks associated with offshore helicopter operations:

• Offshore helicopter operations are often conducted in adverse weather.
• Winds are generally stronger over water than over land, thus making the helicopter harder to control.
• Offshore wind turbines pose a serious threat to helicopters due to their large moving rotor blades (with a length ranging from 30m to 50m).
• High chance of ditching – many system malfunctions have the potential to result in a ditching.
• VTOL capabilities are usually limited to helipads, which restricts one of the main inherent helicopter advantages.
• Autorotation (which can otherwise be a very helpful safety feature) offers limited benefits compared to onshore situations.
• Safety systems are often destroyed or disabled on impact.
• Harsh conditions in water can easily cause a helicopter to capsize.
• Harsh conditions and destroyed or disabled safety and rescue systems reduce the chances of survivors being saved.
• Most fatalities are caused by drowning as occupants are often unable to leave the helicopter in time.

Increasing Survivability

Research has shown that the main reasons for fatalities in offshore operations are drowning and exposure. Impact damage is usually survivable by the occupants.

Therefore, the main focus when discussing safety improvement falls on the increase of post-impact survival rates. There are a number of mitigation measures that are already implemented or are being considered. The most notable of them are:

• Use of floats – these are intended to keep the helicopter upright after ditching long enough to provide safe occupant egress.
• Automatic activation of float systems upon sensing water immersion that would not require pilot interaction. During flight over water, the possibility the automatic float activation being disabled should be minimized.
• Use of life-rafts and life jackets – these are intended to increase survivability after leaving the helicopter. Life-rafts should be externally deployable regardless of whether the aircraft is upright or inverted.
• Use of standard, high-visibility fabric colors and contrasting stripes to assist aircraft search-and-rescue.
• Tear-resistant fabric for float construction. Float bag design should provide a means to minimize the likelihood of tear propagation between compartments.
• Hand-holds on the floats to supplement personal flotation, regardless of helicopter orientation. Handhold/life lines should be installed where practical and feasible to allow person to hold on to an upright or inverted rotorcraft.
• Side floating helicopters concept – if the helicopter remains on its side, there are still doors and hatches above the water. Therefore, research is being done on systems that can prevent total inversion.
• All apertures in the passenger compartment suitable for the purposes of underwater escape should be equipped so as to be usable in an emergency.
• Emergency breathing systems – there are a number of systems that can provide a limited supply of oxygen to occupants that is supposed to be enough for them to safely egress a ditched (and inversed) helicopter.
• There are several issues however, e.g. these devices should be placed in such a way that they remain accessible in all situation but at the same time do not hinder occupant egress.