SEA07LA276
2007-09-02 · Tooele, Utah, United States · None · 1 aircraft · Status: Completed
Airport TVY
Aircraft involved
Probable cause & findings
The loss of engine power for an undetermined reason. Contributing factors were the lack of suitable terrain for the forced landing and the wind shear conditions encountered during the forced landing attempt.
Factual narrative
On September 2, 2007, at 0915 mountain daylight time, a Werner Vari-Eze homebuilt experimental airplane, N547DB, was substantially damaged during a forced landing near Tooele Municipal Airport (KNB), Tooele, Utah. The private pilot, the sole occupant in the airplane, was not injured. The pilot/owner was operating the airplane under 14 CFR Part 91. Visual meteorological conditions prevailed for the personal, cross-country flight that originated from Kanab, Utah, approximately one hour before the accident. No flight plan had been filed. The pilot said that he preflighted his airplane and departed Kanab, with another airplane (a flight of two), at approximately 0818. He said the flight was uneventful but for deviating east of their planned course for thunderstorms. During their descent to Tooele Municipal Airport, they noticed a large thunderstorm over their destination. The other pilot elected to land. He radioed the pilot and said "it was very bumpy, but thought I could handle it." The pilot said he got into severe turbulence on final and elected to go-around. His second approach also terminated with a go-around. During his third approach he had a total loss of engine power. He turned the airplane towards the airfield, but encountered "severe wind shear (down draft)." He picked a field for a forced landing, but he encountered another down draft. During his landing flare, the airplane's main landing gear impacted a ditch and separated from the fuselage. Photographs of the wreckage indicate that the outboard right wing skin had delaminated from the spar and both wing root areas exhibited visible cracks in the upper wing skin. An aerospace engineer from the National Transportation Safety Board said the cracks above the main spar carry through structure indicate hidden damage in the spar. A Federal Aviation Administration inspector and the pilot examined the airplane in the field. They identified no abnormalities with the engine; the reason for the loss of engine power was not determined. The pilot said that as he approached his destination, he noticed a large thunderstorm over the airport. He said that his wingman elected to land, but radioed back to him that it was very bumpy. The pilot said that his first two attempts at landing ended with go-arounds due to severe turbulence. On his third attempt, he lost engine power and selected a field for a forced landing. During the forced landing, he encountered severe wind shear (downdraft) on two occasions. During his landing flare, the airplane's main landing gear impacted a ditch and separated from the fuselage. Photographs of the wreckage indicate that the outboard right wing skin had delaminated from the spar and both wing root areas exhibited visible cracks in the upper wing skin. An aerospace engineer from the National Transportation Safety Board said the cracks above the main spar carry through structure indicate hidden damage in the spar. A Federal Aviation Administration inspector and the pilot examined the airplane in the field. They identified no abnormalities with the engine; the reason for the loss of engine power was not determined. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12
Verbatim from NTSB's published report. Source file
NTSB_2007_SEA07LA276.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
Matched on aircraft type or causal vocabulary (wind shear, go-around, turbulence, thunderstorm). All research papers
- NASA NTRS 2019 · Contractor Report (CR) An Examination of Aviation Accidents Associated with Turbulence, Wind Shear and Thunderstorm
The focal point of the study reported here was the definition and examination of turbulence, wind shear and thunderstorm in relation to aviation accidents.
- NASA NTRS 2019 · Reprint (Version printed in journal) Observations of severe turbulence near thunderstorm tops
Data derived from the flight tapes of two airliners that experienced severe turbulence near thunderstorm tops are used to produce quantitative descriptions of the turbulence and its environment.
- Embry-Riddle Scholarly Commons 2019 · Journal article (IJAAA) Low Level Turbulence Detection For Airports
Abstract—— Low level wind shear and turbulence present a serious safety risk to aircraft during the approach, landing and take-off phases.
- Embry-Riddle Scholarly Commons 2018 · Journal article (IJAAA) Evaluating the Effect of Turbulence on Aircraft During Landing and Take-Off Phases
—— Low level wind shear and turbulence present a serious safety risk to aircraft during the approach, landing and take-off phases.
- NASA NTRS 2019 · Conference Proceedings Operational evaluation of thunderstorm penetration test flights during project Storm Hazards '80
The National Aeronautics and Space Administration is conducting a research project called Storm Hazards '80 in order to study the prediction, detectability and avoidance of the hazards of severe storm…
- NASA NTRS 2019 · Reprint (Version printed in journal) Severe Turbulence and Maneuvering from Airline Flight Records
Digital flight records from reported clear-air turbulence incidents are used to determine winds and turbulence, to determine maneuver g loads, and to analyze control problems.