Lighting upgrades enhance North Sea helicopter safety

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Helideck lighting development has proved to be one of the most fruitful areas of safety enhancement over the last decade and is hoped to lead to the widespread adoption of a new configuration from next year.

The issue sprang to prominence when lighting emerged as an unexpectedly high priority for pilots in a UK Civil Aviation Authority safety survey.

Research pinpointed three issues with helideck lighting schemes at the time: their use of yellow and white lights did not stand out from the rest of the rig lighting; the touchdown spot in the middle of the deck was effectively a "black hole"; and floodlighting used to illuminate the helideck was too bright, with even slight misalignment making things markedly worse.

UK CAA research manager David Howson says: "The science of visual perception is not fully understood so to some extent we have do this by empirical process."

The result has been an extensive series of flight trials over the last five years in which a design has evolved that is now receiving consistently strong reviews by pilots who have experienced it, or elements of it. And the UK Air Accidents Investigation Branch believes its earlier introduction could have helped prevent the loss of a Eurocopter AS365N Dauphin on approach to a gas platform in Morecambe Bay off the west coast of England in December 2006.

Trials quickly determined that a switch to green lighting of the perimeter had major benefits, and that floodlights had no place on a helideck.

 night-helipad-lighting
 © UK CAA
Green perimeter lights proved highly effective

Further trial iterations over several years have resulted in a final configuration with green perimeter lights; a single, broken, yellow touchdown marker circle; and a green hollow-H for the touchdown point itself (see picture).

Howson says concerns that the design might not be compatible with the landing-nets commonly used on helidecks to increase friction proved groundless, and a hollow-H, rather than solid, also mitigated concerns about adding an area of reduced friction.

The early findings resulted in flight trials on the Perenco Thames A platform last year followed by the International Civil Aviation Organisation mandating the green perimeter lights from the beginning of this year, and promulgating the circle and H as "acceptable alternatives" to floodlighting. A number of North Sea platforms have already been equipped with this configuration.

'SIMILARITIES'

Howson notes that there are "similarities" between the Morecambe Bay accident and the loss of a Super Puma in February this year (see panel) that may lead to the current investigation generating a new recommendation supporting lighting upgrades.

He explains that the addition of the circle provides cueing of the correct approach angle as it is perceived by the pilot as an ellipse of changing flatness depending on the angle. The gaps in the broken line give an additional height cue, and the H is acquired at about 0.25nm (0.45km). The crossbar of the H is aligned with the obstacle-free sector of the installation, providing further safety.

A separate, and less mature, research programme funded by the European Union is developing GPS-aided approaches, and Howson says: "The plan then is to do a GPS approach to deliver the aircraft to a known point in space and then pick up the lights rather like a fixed-wing aircraft. GPS and lighting will be the solution in the long term."

Meanwhile, a production lighting system built by a teaming of AGI of Poole, UK and Orga of the Netherlands will undergo trials in November on a Morecambe Bay platform.

"We were always pretty sure about the design of the lighting but what we were less sure about was the effect of weather, fluids, cleaning agents and so on," says Howson. "We have already said 'please try to design it so it costs about the same as a set of floodlights', although we do not know if that can be achieved.

The CAA is planning an interim update to the CAP437 document, which specifies helideck standards.

Howson says: "We will recommend that new installations and any refurbished ones are fitted with it, and on satellite decks we may recommend It more strongly. Oil & Gas UK are very interested so you could see systems being fitted during production next year."

Green perimeter lights proved highly effective

Helideck lighting development has proved to be one of the most fruitful areas of safety enhancement over the last decade and is hoped to lead to the widespread adoption of a new configuration from next year.

The issue sprang to prominence in the late 1990s when lighting emerged as an unexpectedly high priority for pilots in a UK Civil Aviation Authority safety survey.

Research pinpointed three issues with helideck lighting schemes then in use: their use of yellow and white lights did not stand out from the rest of the rig lighting; the touchdown spot in the middle of the deck was effectively a "black hole"; and floodlighting used to illuminate the helideck was too bright, with even slight misalignment making things markedly worse.

UK CAA research manager David Howson says: "The science of visual perception is not fully understood so to some extent we have do this by empirical process."

The result has been an extensive series of flight trials over the last five years in which a design has evolved that is now receiving consistently strong reviews by pilots who have experienced it, or elements of it. And the UK Air Accidents Investigation Branch believes its earlier introduction could have helped prevent the loss of a Eurocopter AS365N Dauphin on approach to a gas platform in Morecambe Bay off the west coast of England in December 2006.

Trials on the K14 platform in the Dutch sector of the North Sea and subsequently on land-based emulations of offshore installations quickly determined that a switch to green lighting of the perimeter had major benefits, and that floodlights had no place on a helideck.

Further trial iterations over several years have resulted in a final configuration with green perimeter lights; a single, broken, yellow touchdown marker circle; and a green hollow-H for the touchdown point itself (see picture).

Howson says concerns that the design might not be compatible with the landing-nets commonly used on helidecks to increase friction proved groundless, and a hollow-H, rather than solid, also mitigated concerns about adding an area of reduced friction.

The early findings resulted in flight trials on the Perenco Thames A platform last year followed by the Internation Civil Aviation Organisation mandating the green perimeter lights from the beginning of this year, and promulgating the circle and H as "acceptable alternatives" to floodlighting. A number of North Sea platforms have already been equipped with this configuration.

Howson notes that there are "similarities" between the Morecambe Bay accident and the loss of a Super Puma in February this year (see panel) that may lead to the current investigation generating a new recommendation supporting lighting upgrades.

He explains that the addition of the circle provides cueing of the correct approach angle as it is perceived by the pilot as an ellipse of changing flatness depending on the angle. The gaps in the broken line give an additional height cue, and the H is acquired at about 0.45km (0.25nm). The crossbar of the H is aligned with the obstacle-free sector of the installation, providing further safety.

A separate, and less mature, research programme funded by the European Union is developing GPS-aided approaches, and Howson says: "The plan then is to do a GPS approach to deliver the aircraft to a known point in space and then pick up the lights rather like a fixed-wing aircraft. GPS and lighting will be the solution in the long term."

Meanwhile, a production lighting system built by a teaming of AGI of Poole, UK and Orga of the Netherlands will undergo trials in November on a Morecambe Bay platform.

"We were always pretty sure about the design of the lighting but what we were less sure about was the effect of weather, fluids, cleaning agents and so on," says Howson.

"We have already said 'please try to design it so that I costs about the same as a set of floodlights', although we do not know if that can be achieved.

"Trial systems have been about £20,000 ($33,000) including installation, which is not a lot more than a set of floodlights."

The CAA is considering an interim update to the CAP437 document, which specifies helideck standards.

Howson says: "We will recommend essentially that new installations and any refurbished ones are fitted with it, and on satellite decks we may recommend It more strongly. Oil & Gas UK are very interested so you could see systems being fitted during production next year."