ANC07LA018

NTSB accident investigation · Piper PA-12 · Glennallen, AK · February 1, 2007

Accident · Minor injuriesLimited investigationFinal report
Date
February 1, 2007, 09:45 local (13:45 UTC)
Place
Glennallen, AK
Injuries
1 minor, 1 uninjured
Damage
Substantial damage
Phase of flight
Maneuvering
Aircraft
N3233MPiper PA-12
Weather
Visual (VMC) · Day
Status
Completed · report May 29, 2007
Report
Approved by Office Director
NTSB office
Alaska Regional Office
Parties
FAA-AL-ANC FSDO 03
FAA report
20070201001599A
Case key
65384

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 failure to maintain adequate airspeed to preclude a stall while maneuvering, which resulted in an uncontrolled descent and subsequent collision with terrain. Factors contributing to the accident were variable wind conditions, and an inadvertent stall.

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 - in flightManeuvering
Airspeed(vs) - not maintainedPilot in commandCause
Weather condition - variable windFactor
Stall - inadvertentPilot in commandFactor
In flight collision with terrain/waterDescent - uncontrolled
Terrain condition - snow covered

Analysis

The commercial certificated pilot was maneuvering to land his ski-equipped airplane on a snow-covered lake during a Title 14, CFR Part 91, personal flight. The pilot reported that he and his passenger were scouting the area for a wolf hunt, and decided to land on a remote frozen lake. While making a slight left turn toward the landing area, he said he encountered a windshear about 20 feet above the ground. He said the airplane was configured with 20 degrees of flaps, and the airspeed was about 45 mph. The pilot indicated the left wing stalled, and the airplane descended, colliding with the surface of the lake. The airplane received structural damage to the left wing, fuselage, and landing gear. The pilot described the wind conditions as light and variable winds, with no gusts. He also indicated that the wind shifted several times after the accident.

Factual narrative

On February 1, 2007, about 0945 Alaska Standard time, a ski-equipped Piper PA-12 airplane, N3233M, sustained substantial damage when it collided with snow-covered terrain while maneuvering to land on a remote lake, about 30 miles northwest of Glennallen, Alaska. The airplane was being operated as a visual flight rules (VFR) local area personal flight under Title 14, CFR Part 91 when the accident occurred. The airplane was operated in visual meteorological conditions by the pilot/owner of Copper Valley Air Service, LLC, Glennallen. The commercial certificated pilot was not injured. The sole passenger received minor injuries. The flight originated at the Gulkana Airport, Gulkana, Alaska, about 0920, and no flight plan was filed.

During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on February 2, the pilot reported that he and the passenger were scouting the area for a wolf hunt, and decided to land on a frozen lake. While making a slight left turn toward the landing area, he said he encountered a windshear about 20 feet above the ground. He said the airplane was configured with 20 degrees of flaps, and the airspeed was about 45 mph. The pilot indicated the left wing stalled, and the airplane descended, colliding with the surface of the lake. The airplane received structural damage to the left wing, fuselage, and landing gear.

On the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by the pilot, the pilot described the weather conditions as clear, visibility unlimited, a temperature of about 15 degrees F, light and variable winds, with no gusts. He also indicated that he observed several wind shifts after the accident.

Aircraft

Registration
N3233M
Reported as
Piper PA-12
Category
Airplane
Serial number
2027
Airframe hours
2,910
Engine
Lycoming O-320-B2D, 150 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Airworthiness certificate
Standard, Normal
Last inspection
100 hour · October 1, 2006 · 11 hours before
Departed
PAGK · Glennallen, 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
45
Injuries
None
Certificate
Commercial
Airplane ratings
Single-engine sea, Single-engine land
Instrument ratings
Airplane
Medical
Class 2, With waivers/limitations
Last flight review
June 1, 2006
Seat
Front
Flight hours
7,000 total · 1,500 in this make and model · 6,200 as pilot in command · 15 in the last 90 days · 11 in the last 30 days

Weather

Conditions
Visual (VMC) · Day
Visibility
60 statute miles
Lowest ceiling
None
Temperature
16 °F

FAA reports on this event · 1

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

Other investigations on N3233M · 3

Matched to the same aircraft by N-number and date.