Sunday, March 17, 2019

Loss of Control in Flight: Cessna 170B, N4385B; accident occurred December 16, 2018 in Riggins, Idaho County, Idaho

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; Spokane, Washington

Aviation Accident Final Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board:

Location: Riggins, ID
Accident Number: GAA19CA098
Date & Time: 12/16/2018, 1200 MST
Registration: N4385B
Aircraft: Cessna 170
Aircraft Damage: Substantial
Defining Event: Loss of control in flight
Injuries: 1 None
Flight Conducted Under: Part 91: General Aviation - Positioning 


The pilot of the ski-equipped airplane reported that he aborted his first attempt to take off, and during his second takeoff attempt with a tailwind, shortly after rotation, the airplane settled back onto the snow-packed runway. He added that the airplane lifted off again, but when it was about 5 ft above the ground and near the end of the runway, a wind gust pushed the airplane down onto the runway. Subsequently, the airplane overran the runway, and the right wing impacted a tree. The pilot did not know the wind direction and speed because the airport did not have a windsock or weather reporting station.

The airplane sustained substantial damage to the wings.

The pilot reported that there were no preimpact mechanical failures or malfunctions with the airplane that would have precluded normal operation.

The pilot chose to depart to the north due to rising terrain and tall trees on the south end of runway. The pilot further reported he had landed and taken off from this airport previously without incident.

The airport elevation was about 7,600 ft, and the runway was 1,800 ft long. The airplane owner's manual recommended a takeoff distance of 3,420 ft at 7,000 ft elevation and 40°F with zero wind velocity and from a hard level surface. The manual also stated that, under the most favorable condition of smooth, packed snow at 30°F, the takeoff distance for a ski-equipped airplane was about 10% greater than that for a wheel-equipped airplane. Per a supplemental type certificate (STC), the airplane underwent an engine conversion to a 180-horsepower, constant-speed propeller engine. No takeoff performance data were provided on the STC.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The pilot's improper preflight performance planning and his subsequent failure to attain sufficient speed for the airplane to climb with a tailwind.


Climb rate - Not attained/maintained (Cause)

Personnel issues
Performance calculations - Pilot (Cause)

Environmental issues
Tree(s) - Contributed to outcome
Tailwind - Response/compensation

Factual Information

History of Flight

Other weather encounter
Loss of control in flight (Defining event)
Collision with terr/obj (non-CFIT)
Runway excursion

Pilot Information

Certificate: Flight Instructor; Commercial
Age: 64, Male
Airplane Rating(s): Multi-engine Land; Single-engine Land; Single-engine Sea
Seat Occupied: Front
Other Aircraft Rating(s): None
Restraint Used: 3-point
Instrument Rating(s): Airplane
Second Pilot Present: No
Instructor Rating(s): Airplane Single-engine
Toxicology Performed: No
Medical Certification: Class 2 With Waivers/Limitations
Last FAA Medical Exam: 03/20/2018
Occupational Pilot:
Last Flight Review or Equivalent: 06/14/2018
Flight Time:  (Estimated) 21500 hours (Total, all aircraft), 2000 hours (Total, this make and model), 21200 hours (Pilot In Command, all aircraft), 137 hours (Last 90 days, all aircraft), 15 hours (Last 30 days, all aircraft) 

Aircraft and Owner/Operator Information

Aircraft Make: Cessna
Registration: N4385B
Model/Series: 170 B
Aircraft Category: Airplane
Year of Manufacture: 1956
Amateur Built: No
Airworthiness Certificate: Restricted; Normal
Serial Number: 26729
Landing Gear Type: Ski; Ski/wheel; Tailwheel
Seats: 4
Date/Type of Last Inspection: 08/29/2018, Annual
Certified Max Gross Wt.: 2200 lbs
Time Since Last Inspection:
Engines: 1 Reciprocating
Airframe Total Time: 6729.8 Hours at time of accident
Engine Manufacturer: Lycoming
ELT: C126 installed, activated, did not aid in locating accident
Engine Model/Series: O-360-4A4
Registered Owner: On file
Rated Power: 180 hp
Operator: On file
Operating Certificate(s) Held: On-demand Air Taxi (135)

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: KGIC, 3314 ft msl
Distance from Accident Site: 28 Nautical Miles
Observation Time: 1935 UTC
Direction from Accident Site: 320°
Lowest Cloud Condition: Scattered / 3000 ft agl
Visibility:  10 Miles
Lowest Ceiling: Overcast / 8500 ft agl
Visibility (RVR):
Wind Speed/Gusts: 8 knots /
Turbulence Type Forecast/Actual: Clear Air / None
Wind Direction: 290°
Turbulence Severity Forecast/Actual: N/A / N/A
Altimeter Setting: 29.98 inches Hg
Temperature/Dew Point: 6°C / -2°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: McCall, ID (KMYL)
Type of Flight Plan Filed: Company VFR
Destination: Riggins, ID (PVT)
Type of Clearance: None
Departure Time: 1015 MST
Type of Airspace: Class G

Airport Information

Airport: Buffalo Hump (Concord) private (PVT)
Runway Surface Type: Snow
Airport Elevation: 7600 ft
Runway Surface Condition: Snow
Runway Used: 01
IFR Approach: None
Runway Length/Width: 1800 ft / 50 ft
VFR Approach/Landing: Full Stop; Traffic Pattern

Wreckage and Impact Information

Crew Injuries: 1 None
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 None
Latitude, Longitude: 45.583611, -115.681667 (est)

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