Wake Vortices Predicted To Be "More Substantial" From New Aircraft.

The FAA has established procedures requiring 10 miles of separation between Boeing's 787 and 747-8 airplanes and aircraft departing or landing behind them. The minimum en-route spacing behind one of Boeing's new airplanes is set at five miles.

In an internal notice to air traffic controllers, the FAA says "(s)tudies indicate that wake vortices generated by the B748 and possibly by the B787 (all variants) may be more substantial than those of aircraft in the “Heavy” wake turbulence category. The FAA Flight Standards Service has not yet issued final standards for either aircraft. Pending the issuance of such standards, the ATO will continue to issue interim guidance to support the operation of the B748, B783, B788, and B789 aircraft in U.S. controlled airspace."

According to the notice, the procedures are based in part on guidance received from the International Civil Aviation Organization and the joint FAA/Euro-Control Wake Turbulence Steering Group that studied the wake vortices of the Airbus 380-800 (A388) in 2006. The B748 is 7 percent heavier than the B747-400 (B744) version and 27 percent lighter than the Airbus A388.

The B787 (all variants) maximum certificated takeoff weight is approximately one-third that of the Boeing 748. The analyses of computational models suggest that the B748 wake vortices are similar to those generated by the B744. The separation standards and procedures contained in this notice are
conservative. Final guidance will become available once the flight test data have been evaluated.

The notice is applicable the Boeing 747-800 (B748) and three variants of the Boeing 787 (B783, B788, and B789) operations, and has a published expiration date of October 31, 2011.

FMI: www.faa.gov, www.boeing.com