Incident Overview
A Cessna 172, while en route between two airports on a heading of approximately 300 degrees, crossed the final approach course to an airport that handles large airplanes. At the same time, a Boeing 757 was on final approach to that airport, heading about 360 degrees. Both aircraft were in communication with approach control, and the pilots acknowledged visual contact with each other. The Cessna pilot also acknowledged a cautionary advisory regarding wake turbulence.
Sequence of Events
The Boeing 757 was descending as the Cessna 172 crossed its flight path approximately 30 seconds after the Boeing had passed through the same altitude. The Cessna pilot reported being thrown about the cockpit as the airplane rolled left and then pitched nose down. The pilot managed to recover to normal flight and subsequently landed at the planned destination.
Post-Flight Examination
A post-flight examination of the Cessna revealed wrinkled skin on the top of the right wing. Further inspection uncovered a cracked rear spar beneath that area.
Environmental Conditions
Surface winds at the time were reported from 300 degrees at 16 knots, with gusts up to 24 knots.
Guidance from Aeronautical Information Manual
The Aeronautical Information Manual recommends that pilots fly at or above the preceding aircraft's flight path and alter course as necessary to avoid the area behind and below the generating aircraft.