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ASN Wikibase Occurrence # 180297
Last updated: 9 January 2020
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Date:10-OCT-2015
Time:17:35
Type:Silhouette image of generic BE35 model; specific model in this crash may look slightly different
Beechcraft G35 Bonanza
Owner/operator:Private
Registration: N4485D
C/n / msn: D-4641
Fatalities:Fatalities: 2 / Occupants: 2
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:Near Lake Tahoe Airport (KTVL), South Lake Tahoe, CA -   United States of America
Phase: Take off
Nature:Private
Departure airport:South Lake Tahoe, CA (TVL)
Destination airport:,
Investigating agency: NTSB
Narrative:
The private pilot and passenger were departing on a personal cross-country flight. During takeoff, witnesses observed that the airplane was struggling to gain altitude and noted that the engine sounded as if it was not producing adequate power. They added that, as the airplane crossed over the airport boundaries, it climbed to about 100 ft above ground level in an excessively high pitch-up attitude. Shortly thereafter, the airplane crossed a ridgeline, entered a nose- and left-wing-low attitude, and impacted the backyard of a residence.
While ceiling and visibility were not an issue in this accident, the wind magnitude and changes in wind direction likely affected the flight. Wind gusts were as high as 26 knots around the accident time, and weather observation sites within 3 miles of the accident site all reported large changes in wind direction around the accident time. Although the wind was mainly from the south to southwest, there were times when the wind came from the west and north. This change in wind direction was likely due to mountain wave conditions and wind flow over the mountainous terrain, and these changes in wind direction and gusts likely affected the accident flight and the pilot’s ability to control the airplane.
Wreckage and impact signatures were consistent with a left-wing-low and nose-low impact. Postaccident examination of the airframe, flight control system, and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Based on the witness observations and the recorded weather data, it is likely that the airplane encountered a downdraft that exceeded the airplane’s climb performance, which resulted in the airplane exceeding its critical angle-of-attack and a subsequent aerodynamic stall.
 An area forecast, issued about 5 hours before the accident, forecasted southwest wind at 20 knots with gusts to 30 knots for the time surrounding the accident. A terminal aerodrome forecast issued 1 hour before the accident, forecasted wind from 190 degrees at 11 knots gusting to 20 knots. However, there is no evidence that the pilot obtained weather information before the flight, thus he may not have been aware of the gusting wind conditions that affected the flight.


Probable Cause: The pilot's inability to maintain airplane control due to an encounter with a downdraft that exceeded the airplane’s climb performance capabilities and resulted in an aerodynamic stall. Contributing to the accident was the pilot’s decision to depart without obtaining a weather briefing.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20151011X04515


Revision history:

Date/timeContributorUpdates
11-Oct-2015 03:20 Geno Added
11-Oct-2015 03:29 Geno Updated [Location, Source, Damage, Narrative]
11-Oct-2015 06:59 gerard57 Updated [Total fatalities, Other fatalities, Departure airport, Narrative]
11-Oct-2015 07:03 harro Updated [Aircraft type]
11-Oct-2015 17:36 Geno Updated [Phase, Source]
12-Oct-2015 16:09 Geno Updated [Aircraft type, Registration, Cn, Operator, Departure airport, Source]
21-Dec-2016 19:30 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
27-Feb-2017 20:01 PiperOnslaught Updated [Source, Narrative]
19-Aug-2017 09:36 ASN Update Bot Updated [Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative]

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