- Date
- July 4, 2000, 11:45 local (18:45 UTC)
- Place
- Grass Valley, CA
- Injuries
- 2 serious
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N91313Thorp T211
- Weather
- Visual (VMC) · Day
- Status
- Completed · report October 17, 2001
- Report
- Approved by Office Director
- FAA report
- 20000704006629A
- Case key
- 49601
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
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Probable cause
the pilot encountered a mountain wave at an altitude too low to maintain clearance from trees.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
The pilot was cruising the local area about 1,000 feet agl, at 2,500 rpm, when the airplane suddenly started to descend. Although he hadn't noticed any evidence of strong winds, he was on the lee side of a peak. He turned to avoid the wind shear and applied full power, but his descent continued. The airplane collided with 100-feet tall trees after he maneuvered to avoid hitting one straight on with the cabin area.
Factual narrative
On July 4, 2000, about 1145 hours Pacific daylight time, a Thorp T211, N91313, sustained substantial damage when it collided with trees while maneuvering near Grass Valley, California. The private pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The pilot and one passenger sustained serious injuries. The personal flight departed Auburn Municipal Airport, Auburn, California, about 1130, and was scheduled to terminate at the Alta Vista, California, airport. Visual meteorological conditions prevailed and no flight plan was filed.
The pilot stated he was cruising the local area about 1,000 feet agl, at 2,500 rpm, when the airplane suddenly started to descend. Although he hadn't noticed any evidence of strong winds, he was on the lee side of a peak. He turned to avoid the perceived wind shear and applied full power, but his descent continued. The airplane collided with 100-feet tall trees in a private campground after he maneuvered to avoid hitting one straight on with the cabin area. One wing folded and the airplane came to rest on its side. The pilot suffered a broken leg, while the passenger suffered a broken arm.
An examination of the airplane's engine by the manufacturer's representative, under the supervision of a Safety Board investigator, did not reveal any discrepancies that would preclude normal operation. The wreckage was released to the owner's agent.
Aircraft
- Registration
- N91313
- Reported as
- Thorp T211
- Category
- Airplane
- Serial number
- 4
- Airframe hours
- 1,255
- Engine
- Lycoming O145-C2, 65 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Registered owner
- Robert L Riddle
- Airworthiness certificate
- Standard, Normal
- Last inspection
- Annual · November 12, 1999 · 5 hours before
- Departed
- AUN · Auburn, CA
- Destination
- Q62 · Alta Vista, CA
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 59
- Certificate
- Private
- Airplane ratings
- Single-engine land
- Medical
- Class 3, Valid Medical--no waivers/lim.
- Seat
- Left
- Flight hours
- 1,800 total · 200 in this make and model · 5 in the last 90 days · 3 in the last 30 days
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 0° at 6 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- None
- Temperature
- 142 °F, dew point 102 °F
- Altimeter
- 30.00 inHg
- Observed at
- BLU, 14 nm away
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.