# NTSB SEA07CA235: Cessna 172B, N7657X, Seattle, WA, August 14, 2007 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: August 14, 2007, 14:00 local (21:00 UTC) - Place: Seattle, WA - Coordinates: 47.616664, -122.26667 - Nearby events: https://openairdocs.org/map.md?lat=47.6167&lon=-122.2667&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report November 29, 2007 - Report: Approved by Office Director - NTSB case key (mKey): 66440 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA07CA235 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/66440/pdf - Page: https://openairdocs.org/ntsb/SEA07CA235 ## Probable cause 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. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - On ground/water encounter with terrain/water, takeoff - roll/run - visual lookout - inadequate, pilot in command (cause) - supervision - inadequate, pilot in command(cfi) (cause) - terrain condition - large wave/swell (contributing factor) ## Analysis 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. ## Factual narrative 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. ## Aircraft - Registration: [N7657X](https://openairdocs.org/aircraft/N7657X), registered now, S/N 17248157, built 1960 (OpenAirDocs) - Reported make and model: CESSNA 172B - Registry model: [Cessna 172B](https://openairdocs.org/model/cessna-172b) (registry code 2072406) (OpenAirDocs) - Registry engine: [Continental 0-300 series](https://openairdocs.org/engine/continental-0-300-series) (registry code 17022, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 17248157 - Airframe hours: 2954 - Engines: Lycoming O-360-A1A reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Stephen A. Tibbitts - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 1, 2007 - Departed: Seattle, WA - Destination: Spanaway, WA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 52; commercial, flight instructor; airplane ratings: single-engine sea, single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2; last flight review October 1, 2005; flight hours: 6,988 total, 1,001 in this make and model, 52 in the last 90 days, 9 in the last 30 days - Pilot; age 47; private; airplane ratings: single-engine land; medical: class 3; last flight review October 1, 2005; flight hours: 104 total, 45 in this make and model, 22 as pilot in command, 45 in the last 90 days, 9 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 10° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 72 °F ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20070814018179A](https://openairdocs.org/incident/20070814018179A), Aug 14, 2007: Cessna 172B, Lake Washingto, WA, Substantial damage. (-23) Aircraft was departing lake Washington and hit a large wake at approx 40 knots causing the float struts and brace wires to break and the right wing strut… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.