A380 Makes Big Waves... In Its Wake

If "conservative" computer models generated by the International Civil Aviation Organization prove accurate, airplanes following the A380 will have to fly up to three times the normal distance behind the massive airliner in order to avoid its wake turbulence. Such requirements could put some airports' plans to handle the superjumbo in a tailspin.

According to the London Sunday Times, the ICAO models show the double-decker aircraft will produce "significantly stronger" wake vortices off its wingtips than either the Boeing 747 -- the largest commercial airliner flying at the moment -- and even the Boeing 757, a notorious wake generator.

"To date, we've come up with some preliminary guidelines for the aircraft... in normal air traffic control operations," said ICAO spokesman Denis Chagnon to Aero-News. "The models reveal the horizontal vortex may have been larger than anticipated, than even the vertical one."

The required safety guidelines, issued earlier this month, recommend aircraft flying directly behind an A380 at cruising altitude should keep minimum spacing of 15 nautical miles, compared to the industry standard of five n.m. On final approach, a minimum 10 n.m. separation would be required -- far above the standard of 3-8 nautical miles currently in force, depending on the comparative sizes of the aircraft.

Combined with an additional minute added to departure regulations for aircraft taking off behind an A380, and the wake turbulence guidelines become a real issue -- and puts to question just how much the A380's added passenger capacity offsets such issues.

"If the wake vortex requires separation larger than the 747... it would require adjustments in air traffic control operations," said Chagnon.

(Editor's Note: You may listen to our entire conversation with Chagnon in today's Aero-News Aero-Briefing, available here.)

Wake vortices are essentially "mini-tornados" formed by air rolling off the plane's wingtips (and, to a far lesser extent, the horizontal stabilizer) anytime those surfaces are generating lift. Aircraft encountering these vortices can be displaced, much like when they encounter regular turbulence.

In extreme cases, an aircraft that encounters a strong wake vortex can lose control completely.

Many in the industry believe the ICAO guidelines, which were based off flight tests of the A380 prototypes, are conservative... which is something Airbus is counting on.

"We don’t want to jump to any conclusions," said an Airbus spokesman. "We are still expecting the (wake of the) aircraft to be similar to the 747."

The guidelines will not be finalized until summer of 2006.

FMI: www.icao.org