NTSB Identification: SEA07CA235
14 CFR Part 91: General Aviation
Accident occurred Tuesday, August 14, 2007 in Seattle, WA
Probable Cause Approval Date: 11/29/2007
Aircraft: CESSNA 172B, registration: N7657X
Injuries: 2 Uninjured.

NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.

During the floatplane instructional flight, the private pilot decided to make a practice landing and takeoff on a large lake. Although the landing on the calm water was uneventful, during the takeoff run, just before liftoff, the aircraft encountered the wake of a large boat. As the aircraft crossed the crest of the first wave of the wake, it became momentarily airborne, and then it impacted the advancing forward face of the second wave. At the moment of impact, four of the float attach fittings failed. The pilot therefore immediately aborted the takeoff, but the right wing impacted the surface of the water before the aircraft came to a stop. Neither the private pilot nor the instructor pilot that was supervising him had seen the large swell approaching during the landing, and during the takeoff run, neither of them noticed it until a few seconds prior to the time the aircraft impacted it.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The private pilot's failure to see the approaching large wake swell, both during his landing and the subsequent takeoff, and the failure of the instructor pilot to insure that the private pilot's visual lookout was effective enough to detect the oncoming wake. Factors include a wake generated by a large boat.

Full narrative available

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