Weather (Other) · NTSB WPR16FA007

BEECH G35 — South Lake Tahoe, CA

2 fatal High-time pilot
DateOctober 11, 2015
LocationSouth Lake Tahoe, CA
AircraftBEECH G35
Purpose of flightPersonal
ConditionsDay · Visual Meteorological Cond
Phase / occurrenceEnroute-climb to cruise Turbulence encounter
Pilot age73
Pilot total time1,580 hrs · Experienced
Time in type158 hrs
Fatalities2

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.

NTSB findings

  • Aircraft-Aircraft oper/perf/capability-Aircraft capability-Climb capability-Capability exceeded - C
  • Personnel issues-Task performance-Use of equip/info-Aircraft control-Pilot - C
  • Environmental issues-Conditions/weather/phenomena-Wind-Downdraft-Effect on operation - C
  • Personnel issues-Action/decision-Info processing/decision-Decision making/judgment-Pilot - F

What happened

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.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.

View the official NTSB docket →