Offshore surveillance system

The first helicopter surveillance system for offshore operations has been launched for the North Sea by Oil & Gas UK and NATS Services.

It is claimed the system will enable air traffic controllers to see helicopters on their radar screens at Aberdeen Airport at a far greater range from the shore than has previously been possible using solely shore-based radars.

Oil & Gas UK and NATS Services hope the new system will further reduce the risk of near miss incidents with other aircraft and increase the speed and efficiency of search and rescue operations.

The Helicopter Task Group, one of the main promoters of the project, has hailed the system as a breakthrough in helicopter safety.

‘Previously, helicopters were lost to land-based radar at about 80 miles from the coast, because radar coverage doesn’t extend beyond that distance,’ said Bob Keiller, chair of the Helicopter Task Group.

‘The new system uses multilateration to allow flight paths to be tracked all the way to an installation in real time. It is designed to detect aircraft up to 500ft above sea level or better, depending on the helicopter's position.’

Multilateration uses multiple position points to determine the exact location of a helicopter. To provide maximum coverage, equipment is being fitted to 16 host platforms, which have been divided into four clusters, each of four platforms.

As soon as a helicopter leaves the 80-mile radar zone, its transponder responds to a signal that is then detected by receivers on each of the four platforms in a cluster, allowing complete surveillance of the helicopter flight. This data is then sent to the control tower building (CTB) at Aberdeen Airport via the oil company data links.

Computer analysis at the CTB determines the helicopter position by triangulation. Only three signals need to be received in order to provide a position, but the fourth signal increases accuracy and gives some redundancy should a signal not be received.

NATS Services have completed three of the four clusters and flight trials have commenced to ensure the coverage is complete from these three clusters and that the system accuracy is within the expected limits.

The second phase of the flight trials is due to begin in January 2010. NATS Services expects all four clusters to be fully operational by June 2010.

The entire system will deliver surveillance and voice communications improvements for 25,000 square miles of airspace over the North Sea.

Robert Paterson, health, safety and employment issues director with Oil & Gas UK, said in addition to this new visual tracking system, the oil and gas industry recently upgraded VHF voice communication with offshore helicopters by modernising and extending existing offshore rebroadcasting facilities.

‘Rebroadcasting facilities enable the controllers to speak directly with helicopter crews through the use of offshore radios linked to shore,’ he added. ‘The new extension and upgrades ensure that the whole of the North Sea is now covered by voice communication. Improving radar and radio coverage for helicopter flights is a big step forward.'