By Max Kingsley-Jones in Toulouse

Airbus is confident that the International Civil Aviation Organisation (ICAO) will agree to relaxed in-flight separation distances for the A380 before it enters service. This follows the failure by ICAO’s A380 wake vortex working group earlier this month to sign off less-draconian requirements than the interim recommendations issued in November last year. The working group is expected to present its final report in November.

Last year’s interim requirements – which Airbus has strongly contested – resulted from concerns within ICAO that the A380’s wake vortices were greater than those of the Boeing 747 (categorised as “heavy” in wake terms). ICAO recommended that A380 separation distance to any other category of aircraft on approach be a minimum10nm (19km).

The current requirement for the distance between two heavy category aircraft is 4nm, increasing to 5nm for medium category aircraft and 6nm for small category aircraft. The A380’s separation distance in the cruise was also increased from the heavy aircraft’s 5nm (to any other aircraft) to 15nm.

The ICAO A380 working group, which met in Montreal earlier this month to discuss the relaxation of the interim recommendations, broke up without agreeing new limits. “It was agreed that the existing limits were too conservative and that a new set of interim requirements would be established, pending additional information from Airbus,” says Airbus’s senior vice-president flight test, Fernando Alonso.

Airbus senior vice-president flight division, Claude Lelaie, says that during the Montreal meeting it was established that “in some areas information was missing” and further back-to-back tests will be carried out “in the coming days”, but “targets” have been set for new interim recommendations, which “will still be conservative. We have further meetings planned and aim to have these new interim recommendations issued before entry into service,” he says.

The target for the new A380 separation distances are likely to be:

■ Heavy – 6nm;
■ Medium – 7nm;
■ Light – 9nm

“We believe that these should be the targets for the interim situation and that they are conservative,” says Lelaie. “Then we will see what will happen [for the longer term].”

Lelaie is hopeful that ICAO will recommend that the distance between two A380s on approach be 4nm. He also suggests that the distance between an A380 and a 747 could be reduced to 3nm when the latter is in trail, because of its greater size. He adds that he expects an additional 30s hold to be required for aircraft departing behind an A380. The current recommendation is 3min compared to 1-2min for heavy category aircraft, depending on routings.

Source: Flight International