ANC07LA044

NTSB accident investigation · Piper PA-12 · Koyukuk, AK · June 11, 2007

Accident · Serious injuriesLimited investigationFinal report
Date
June 10, 2007, 17:00 local (Jun 11, 2007, 01:00 UTC)
Place
Koyukuk, AK
Injuries
1 serious, 1 minor
Damage
Substantial damage
Phase of flight
Landing
Aircraft
N78492Piper PA-12
Weather
Visual (VMC) · Day
Status
Completed · report November 29, 2007
Report
Approved by Office Director
NTSB office
Alaska Regional Office
Parties
Fairbanks, FSDO-01
FAA report
20070610011389A
Case key
65959

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's inadequate compensation for a gusting tailwind during the landing roll, which resulted in a loss of control and a nose over. Factors contributing to the accident were the tailwind and wind gust.

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.

Loss of control - on ground/waterLanding - roll
Weather condition - gustsFactor
Weather condition - tailwindFactor
Compensation for wind conditions - inadequatePilot in commandCause
Nose overLanding - roll

Analysis

The airline transport certificated pilot was attempting to land the tailwheel-equipped airplane on a mountain ridge under Title 14, CFR Part 91. He said landing uphill necessitated landing with a tailwind. He reported that during the landing roll a gust of wind picked up the tail, and rolled the airplane upside down. The pilot said the airplane sustained damage to both wings and the rudder.

Factual narrative

On June 10, 2007, about 1700 Alaska daylight time, a tailwheel-equipped Piper PA-12 airplane, N78492, sustained substantial damage when it nosed over while landing on a mountain ridge, about 41 miles northwest of Koyukuk, Alaska. The airplane was being operated by the pilot as a visual flight rules (VFR) personal cross-country flight under Title 14, CFR Part 91, when the accident occurred. The airline transport certificated pilot received serious injuries, and the sole passenger received minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed. The flight departed the Unalakleet Airport, Unalakleet, Alaska, about 1500.

During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on June 15, the pilot said the mountain ridge where he intended to land looked smooth, free of rocks, and flat on top. He said the ridge sloped upward about 8 degrees, and he intended to land upslope. The pilot said an upslope landing necessitated he land with what he estimated to be about a 5 knot tailwind. According to the pilot, after the main landing gear touched down the airplane rolled into a depression on the ridge, and he believed that rolling into the depression exposed the underside of the tail to the tailwind, which flipped the airplane onto its back. He said there were no preaccident mechanical anomalies with the airplane prior to the accident, and that both wings and the fuselage were damaged during the accident.

Aircraft

Registration
N78492
Reported as
Piper PA-12
Category
Airplane
Serial number
12-3903
Airframe hours
1,762
Engine
Lycoming O-360-P, 180 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Registered owner
James Tweto
Airworthiness certificate
Standard, Normal; Standard, Utility
Last inspection
Annual · June 1, 2006
Departed
PAUN · Unalakleet, AK
Destination
Koyukuk, AK

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
52
Injuries
Serious
Certificate
Airline transport
Airplane ratings
Multi-engine land, Single-engine land
Instrument ratings
Airplane
Medical
Class 2, With waivers/limitations
Last flight review
September 1, 2006
Seat
Front
Flight hours
20,000 total · 1,000 in this make and model

Weather

Conditions
Visual (VMC) · Day
Wind
Variable at 10 knots
Visibility
10 statute miles
Temperature
61 °F

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.