The business jet was descending through 14,000 feet for landing at Washington Dulles International Airport in smooth air with light winds when a sudden bout of turbulence rolled the aircraft 60 degrees to the right.
“As quickly as the encounter occurred, it was over,” the Falcon 2000’s captain wrote in a report of the event, adding that the crew responded by disconnecting the autopilot and stabilizing the twin-engine jet.
What seems different about this example of a wake-turbulence encounter from those typically presented in discussions of the hazard?
Typical scenarios student pilots study concern flight near the surface. You learn to visualize and avoid flying through the wake of larger aircraft taking off or landing, say, by becoming airborne before the point where a departing large aircraft broke ground, and remaining above its wake, or by landing beyond where a heavier aircraft touched down. Also, vortices drift in the wind, requiring pilots of following aircraft to visualize the probable movement.
Those lessons are safety-critical. But they’re not the whole story, any more than practicing collision avoidance only in the vicinity of an airport would be the whole story of see-and-avoid operations. The techniques apply in all flight phases.
“Government and industry groups are making concerted efforts to minimize or eliminate the hazards of trailing vortices. However, the flight disciplines necessary to ensure vortex avoidance during VFR operations must be exercised by the pilot. Vortex visualization and avoidance procedures should be exercised by the pilot using the same degree of concern as in collision avoidance,” cautions section 7-3-8 of the Aeronautical Information Manual.
If the idea of a 42,000-pound corporate jet flown by a seasoned crew being rolled 60 degrees in a wake encounter seems startling, note that a Boeing 777 weighs 545,000 pounds or more. As the Aeronautical Information Manual notes, every aircraft generates a wake in flight, and “the vortices from larger aircraft pose problems to encountering aircraft.”
As the pilot of a potential “encountering aircraft,” stay vigilant for all possible wake-turbulence scenarios.