Farnborough Air Show

Airbus awaits answer on new A380 wake proposal

 - November 15, 2006, 6:21 AM

Airbus has issued a new “conservative and interim” recommendation for A380 separation minimums backed by 100 hours of flight testing performed in Toulouse, Istres and Frankfurt. According to Airbus’ calculations, an A380 can safely trail another A380 as close as four nautical miles on approach, all other “heavy” aircraft can follow as close as six nautical miles, medium-weight-class aircraft as close as seven miles and light aircraft as close as nine miles. Today’s standards for landing behind a heavy airplane other than an A380, such as a Boeing 747, call for separation of four nautical miles for another heavy aircraft, five nautical miles for a medium-weight aircraft (for example, an A320) and six miles for a light aircraft.

The International Civil Aviation Organization’s (ICAO) interim guidelines for the A380, adopted last November, caught Airbus by surprise. They require minimum spacing of 10 nm between a landing super jumbo and a following aircraft, regardless of weight. For aircraft flying behind an A380 on the same route and at the same altitude, ICAO proposes tripling the present minimum distance to 15 nm. The interim guideline also recommends extending wait time by one minute–beyond today’s typical two minutes–for smaller aircraft waiting to take off behind an A380.

During a briefing at Airbus headquarters last month, company flight division senior vice president Claude Lelaie expressed frustration with what he characterized as the regulators’ lack of understanding of the issue. “I will not even comment” on the 10-nm interim requirement, Lelaie said with a hint of derision.

“If the A380 has a stronger vortex than the 747, then the A380 must be able to resist the wake vortex of the 747 easier,” he reasoned, adding that “perhaps” ICAO should allow a three-nautical-mile separation between a 747 and a following A380. “If we are going to add a fourth class, then we should go in both directions.”

Airbus expected ICAO to decide on its recommendations by the third quarter.

Airbus Suspects Foul Play

While, publicly, Airbus is taking a tactful approach to resolving the A380 wake vortex question, privately it is angered by what it views as foul play over a safety issue. A senior company official told Aviation International News on condition of anonymity that his company’s U.S. competition is using the temporary restrictions to harm the A380’s reputation with prospective customers and also with airports. He went so far as to allege that “interested parties” in the U.S. Federal Aviation Administration are using ICAO “in the interests of the competition,” adding, “It looks like they are plotting against us.”

Representatives of ICAO, FAA, Europe’s Joint Aviation Authorities and other regulating structures established the ICAO commission in 2003 to jointly address the issues of A380 suitability. The Airbus source alleged that from the beginning “certain commission members” have been more interested in finding reasons to delay and obstruct the development and certification of the A380. One of these obstacles, he insisted, has been the commission’s decision to ask Airbus for extra test flights. These flights went above and beyond the previously agreed test framework laid out by the FAA and JAA (now EASA) for type certification of the new airliner.

Airbus’ frustration is fueled partly by the fact that neither Europe’s JAR 25 requirements nor U.S. FAR 25 regulations contain special requirements addressing wake vortices. Dismissing the restrictions as “ridiculous,” the Airbus source pointed out that the Boeing 747, the world’s largest aircraft when it was developed, did not face any special ICAO requirements concerning vortices when it entered service more than 30 years ago. Similarly, the giant Russian Antonov An-124 Ruslan and An-225 Mriya transports did not encounter special restrictions during their certification processes.

The A380 is not the world’s largest aircraft. It is smaller that the An-225 Mriya freighter in both maximum takeoff weight and wing size. At 640 metric tons maximum takeoff weight, the Mriya is 80 metric tons heavier than the largest A380-800. The Mriya has visited a number of airports around the world, including in the U.S., Europe, Africa and Asia, with no special restrictions being placed on it yet.

The Airbus sources, however, did confess that the A380’s vortex intensity measured in real flights has been somewhat above expectations. This finding gave the ICAO commission the grounds to impose special limitations on the European jet as a temporary measure. But it is still not clear how “temporary” these restrictions will prove to be given that this subject is not yet covered in any detail by international standards.