AVIATION/ FAA ORDERS EXTRA DISTANCE BEHIND 787 & 747-8

The FAA has issued an interim requirement that planes landing after either of Boeing's 2 new aircraft, the 787 Dreamliner and the 747-8 jumbo jet, stay at least 10 miles behind. The current requirement for large airplanes, including the 747-400 now in service, is just 4 miles separation from other heavy jets and up to 6 miles from light aircraft. The FAA said the requirement will ensure that other airplanes are not subject to "wake turbulence," which is a severely disruptive air flow that is generated at the wingtips of big airplanes and swirls backward in a spiraling vortex. "Studies indicate that wake vortices generated by the B747-8 and possibly by the B787 (all variants) may be more substantial than those of aircraft in the 'heavy' wake turbulence category," the FAA ruling said. If the rule were to become permanent, the lengthy separation from other planes would be a major problem for Airlines operating the new Boeing jets. It would reduce the number of airplanes that could fly into a congested Airport and add to flight delays. However, this is not the final standard. The FAA termed the interim standard "conservative," and said final guidance will be issued after 787 and 747-8 flight tests are completed and evaluated. Boeing expects to complete flight tests on the Dreamliner in time for an initial delivery to ANA by mid-February. The 747-8 won't be delivered until mid-2011. The FAA said the interim standards are based in part on guidance received from the international regulatory organizations that studied the wake vortices of the Airbus 380-800 in 2006. In general, the bigger and heavier the plane, the greater the wake turbulence. In 2006 the International Civil Aviation Organization issued a 10-mile separation standard for the A380 superjumbo jet. This was later relaxed, but a separation of 6 to 8 miles is still required for the A380, depending on the size of the aircraft behind it. The 747-8, though heavier than the 747-400, is 27% lighter than the A380. And the 787 Dreamliner's maximum takeoff weight is approximately 1/3 that of the 747-8. The FAA rule takes effect November 1.