Helicopter operations play a crucial role in oil & gas exploration, drilling and production facilities located offshore, hence, safe operations of helicopters during landing and take-off assume great significance. As compared to land operations, operation of helicopters from offshore helidecks involve greater risks due to increased distances between landing sites and adverse weather conditions offshore. Environmental conditions on the offshore helidecks like wind turbulence and hot gas exhaust fumes also pose risk to the safe operations of the helicopters. Helidecks should be designed to improve the environmental conditions for safe landing and take-off.
Helicopter operations on offshore sites act as one of the main sources of risk for offshore workers. Even on highly modernized offshore sites, helicopter operations pose a serious threat to the safety of the man and material.
Bell Energy provides consultancy services for management of helicopter operation risks which include:
A number of fatal incidents have taken place on the offshore sites. Offshore oil & gas installations in North Sea witnessed a series of severe accidents in 1973, 1977 and 1978, resulting in 34 fatalities.
Offshore helicopter crashes have caused loss of many lives around the globe. During 1970-2000 in Western Europe, almost 145 deaths were caused due to 19 helicopter related accidents. Out of these, almost 14 incidents occurred due to crashing of helicopters in the sea, killing almost all the people on board. The Chinook helicopter crash off Shetland in 1986 was the most devastating, resulting in the death of 44 people. The Mumbai High incident occurred in November 2015 resulting in the death of two helicopter pilots, while conducting a night landing test. In April 2016, Helicopter carrying 13 offshore workers crashed near Bergen, offshore Norway. Similar helicopter crash accidents have been reported in Nigeria in 2015.
The incidents related to the crashing of helicopters at offshore Oil & Gas sites may be attributed to many factors:
The risks associated with the helicopter operations at offshore Oil & Gas installation are:
For helicopters, In-flight risk is often assumed to be proportional to distance (or time), but there are additional components due to take-off and landing, which are assumed to be proportional to the number of flight-stages. The overall individual risk per journey is then:
Individual Risk Per Journey = Individual Risk per hour in flight x Flying Time + Individual Risk on take-off or landing x Flight Stages
Helicopter incidents statistics presented by International Oil & Gas Producers (IOGP) database provides the following values for calculation of Individual Risk
Individual risk due to helicopter transportation is calculated as, the combination of the number of helicopter operations on the offshore installations and flight duration.
Apart from the risk to helicopter crew, there could be accidents involving helicopters which can cause damage to the offshore platforms. Based on the accident outcomes in North Sea, the below event tree shows the probabilities of such accidents:
The helideck is away from the process platform and such accidents resulting in helicopter crash into process equipment is highly unlikely.
The threats and consequences of a helicopter crash accident is presented below in form of Bowtie diagram: (left side represents threats which can lead to helicopter crash; right side represents the consequences due to helicopter crash)
The following safety measures or barriers have been identified to reduce risk of helicopter crash:
The threat barriers or safety measures have been presented below:
The risk related to the operation of the helicopters for transportation in offshore installations is inevitable, but in recent times the accident rates have fallen worldwide due to incorporation of several safety measures. Risks to passengers and aircrew on board helicopters flying offshore are similar to those from scheduled flights in comparably-sized fixed-wing aircraft. The main risk is to helideck crew.
The risks associated with helicopter operations for transportation have come to be accepted by many workers as part of the occupational risk of working offshore. Alternatively, ships may be used for transportation, but that would involve much greater risk with increased costs and inconvenience.
A global consensus to share information related to past incidents and accidents may help all the Oil & Gas companies to learn from those incidents and mitigate the risk more effectively.