Lessons learned from studies of the wake turbulence generated by the Airbus A380 may lead to a reassessment programme for the wake characteristics of all large aircraft.

Tests by the US Federal Aviation Administration, Eurocontrol and the European Joint Aviation Authorities have, in an exhaustive and ongoing test programme, established that the A380’s wake vortices contain significantly more energy and behave differently compared with existing in-service large aircraft, says the International Civil Aviation Organisation.

Director of the ICAO air navigation bureau Bill Voss, an observer of the A380 wake studies, says it is relevant to carry out similar analyses of other large aircraft, such as the Antonov An-124 and An-225.

“Bearing in mind what we have learned, we may have to go back into the issue of wake vortex criteria globally [for heavy aircraft],” says Voss. Aerodynamic mathematical modelling of wake vortex strength and behaviour, developed over the past 10 years, is now proving highly accurate, he says. Also, wake vortex detection technologies such as Lidar have become more effective than previous methods, making it easier to validate research.

The operator of London Heathrow airport, BAA, says it understands the ICAO guidance on aircraft separation behind the A380 is interim, awaiting final test validations in mid-2006. However, it is working on Airbus’s advice that final separations are unlikely to exceed those required for the Boeing 747. National Air Traffic Services (NATS), provider of air traffic control at Heathrow, says ICAO has given the guidance only for route-proving flights, with final figures to follow next year. NATS previously said that any aircraft type requiring greater separation than the 747 that uses the airport regularly might cause the loss of two aircraft movements an hour.

The UK CAA says its guidance for approach separation for a narrowbody aircraft behind a 747 is 8nm (14.8km). ICAO advises that spacing behind an A380 should be 10nm. For departures, the CAA rule is 3min behind a 747, and for the A380 ICAO advises an additional minute.


Source: Flight International