RAYTHEON E-SYSTEMS is to develop a laser-based landing aid for US Navy aircraft carriers. The company has received a $4.5 million contract to produce an initial three long-range line-up systems (LRLS), two of which will be installed on carriers.

The system uses highly visible, but eye-safe, laser beams to give the pilot flightdeck-alignment cues several kilometres from the ship, well beyond range of the carrier's lamp-based landing aid. The LRLS produces a fan of coloured laser light, which ranges from flashing red through solid amber (on the centreline) to flashing green, and which mimics the existing "stoplight" alignment system.

Tom Burgher, Raytheon E-Systems director of international and advanced programmes, says that, with the conventional lamp-based system, colour changes with distance - such that the amber centreline indication is absorbed by the atmosphere, limiting its range. The laser light is not absorbed "-and colours stay the same 6-7nm [11-13km] from the ship".

The LRLS is more covert, says Burgher, as the beams are visible only within a narrow arc close to the approach centreline. "You have to be along the beam to see it," he says. About 1km from the ship, the beams drop from view and the pilot switches to conventional lamp-based alignment for final approach.

A six-month sea trial of a prototype system has been conducted on the carrier USS Constellation and, according to Burger, landing-safety officers believe that pilots are as proficient after three to four landings using the LRLS as those completing 30-50 landings using the conventional alignment system.

The LRLS costs $200,000-300,000, and the Navy plans to acquire 31 systems for carriers and training bases. Possible future applications include helicopter carriers and helicopter-equipped warships. Raytheon E-Systems has also proposed a covert, portable system to the US Air Force. This uses infra-red lasers and flash rate instead of colour.

Source: Flight International