ANC09LA038

NTSB accident investigation · Cessna TU206 · Bethel, AK · May 6, 2009

Accident · Minor injuriesLimited investigationFinal report
Date
May 6, 2009, 09:03 local (17:03 UTC)
Place
Bethel, AK
Injuries
1 minor
Damage
Substantial damage
Phase of flight
Initial climb
Aircraft
N629SPCessna TU206
Defining event
Initial climb: Loss of control in flight
Weather
Visual (VMC) · Day
Status
Completed · report July 22, 2010
Report
Approved by Office Director
NTSB office
Alaska Regional Office
Parties
FAA Anchorage FSDO
FAA report
20090506025169A
Case key
73787

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

On this page

Probable cause

The pilot’s failure to remove visible frost from the wings during the preflight inspection, and his failure to maintain adequate airspeed to avoid a stall. Contributing to the accident were conditions conducive to structural icing/frost.

Findings · 5

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

Inspection: preflight inspectionPersonnel issues › Task performance · PilotCessna TU206F: 1 caseAll aircraft: 551 casesProbable cause
Performance/control parameters: airspeedAircraft › Aircraft oper/perf/capability · Not attained/maintainedCessna TU206F: 1 caseAll aircraft: 1,681 casesProbable cause
Temp/humidity/pressure: conducive to structural icingEnvironmental issues › Conditions/weather/phenomena · Effect on operationCessna TU206F: 1 caseAll aircraft: 103 casesProbable cause
LoadingAircraft › Aircraft handling/service · Incorrect use/operationCessna TU206F: 1 caseAll aircraft: 35 cases

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

Analysis

The airplane was taking off on the first flight of the day and had accelerated normally during the short field takeoff roll. During entry into the initial climb, the airplane suddenly rolled into an uncommanded left bank and entered an uncontrolled descent. The left wingtip struck terrain to the left of the runway approximately 1,000 feet from the beginning of the takeoff roll. The airplane came to rest upright approximately 200 feet from the initial impact point. During the impact sequence the unsecured cargo shifted forward and struck the back of the pilot’s seat and the right side of the instrument panel. The pilot exited the airplane unassisted. Photos taken 5 minutes after the accident show the leading edges and tops of the wings, and horizontal tail surfaces were covered in rough frost. The photos also show the frost appears to have been scraped off of most of the windshield. There was substantial damage to the left wing, nose gear, firewall, forward empennage, and both wingtips.

Factual narrative

On May 6, 2009, at 0903 Alaska daylight time, a single engine Cessna TU206F airplane, N629SP, sustained substantial damage when it collided with terrain during takeoff at the Bethel Airport, Bethel, Alaska. The airplane was being operated by Alaska Scenic Air LLC, Eagle River, Alaska, as a visual flight rules (VFR) on-demand cargo flight, under the provisions of Title 14 Code of Federal Regulations (CFR) Part 135. The solo commercial pilot sustained minor injuries. Visual meteorological conditions prevailed at the airport, and company flight following procedures were in effect. The flight was en route to Kasigluk, Alaska. The airplane was taking off on the first flight of the day and had accelerated normally during the short field takeoff roll. During entry into the initial climb, the airplane suddenly rolled into an uncommanded left bank and entered an uncontrolled descent. The left wingtip struck terrain to the left of the runway approximately 1,000 feet from the beginning of the takeoff roll. The airplane came to rest upright approximately 200 feet from the initial impact point. During the impact sequence the unsecured cargo shifted forward and struck the back of the pilot’s seat and the right side of the instrument panel. The pilot exited the airplane unassisted. Photos taken 5 minutes after the accident show the leading edges and tops of the wings, and horizontal tail surfaces were covered in rough frost. The photos also show the frost appears to have been scraped off of most of the windshield. An FAA inspector, who responded to the scene, said the nose gear collapsed and there was structural damage to the firewall, forward empennage, and both wingtips. The left wing had a significant buckle at wing station 100, causing the outboard leading edge skin to open up and the inboard inner spar skin to buckle downward. At 0853, an aviation routine weather report (METAR) at Bethel, Alaska, reported wind from 330 degrees at 8 knots, 10 miles visibility, few clouds at 700 feet, temperature 27 degrees, dew point 23 degrees, and an altimeter setting of 29.93 inches of Mercury.

Aircraft

Registration
N629SP
Reported as
Cessna TU206 (F)
Category
Airplane
Serial number
U20602070
Airframe hours
3,092
Engine
Continental IO520, 300 horsepower, reciprocating
Damage
Substantial damage
Flight
Part 135
Operator
Alaska Scenic Air LLC
Registered owner
Cessna 206 LLC
Airworthiness certificate
Standard, Normal
Last inspection
Annual · March 3, 2009 · 35 hours before
Departed
PABE · Bethel, AK
Destination
PFKA · Kasigluk, AK
Flight plan
Company VFR
Airport
PABE · Bethel Airport, runway 29, 1,860 × 75 ft, gravel

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
71
Injuries
Minor
Certificate
Commercial
Airplane ratings
Single-engine land, Single-engine sea
Instrument ratings
Airplane
Medical
Class 2, With waivers/limitations
Last flight review
April 8, 2009
Seat
Left
Flight hours
8,089 total · 438 in this make and model · 8,089 as pilot in command · 52 in the last 90 days · 30 in the last 30 days

Weather

Conditions
Visual (VMC) · Day
Wind
330° at 8 knots
Visibility
10 statute miles
Temperature
27 °F, dew point 23 °F
Altimeter
29.93 inHg
Observed at
PABE, 1 nm away

Docket · 12

The files NTSB released with the investigation on June 14, 2010, on NTSB’s docket system: statements, records, photos and specialists’ reports.

FAA reports on this event · 1

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