Bethel - Hooper Bay - Scammon Bay

About 0800, the commercial pilot did a preflight inspection of the accident airplane, in preparation for a cargo flight. Dark night, visual meteorological conditions prevailed. He indicated that the weather conditions were clear and cold, and frost was on the airplane. He said the frost was not bonded to the skin of the airplane, and he was able to use a broom to clean off the frost, resulting in a clean wing and tail surface. He reported that no deicing fluid was applied. After takeoff, he retracted the flaps to about 5 degrees at 110 knots of airspeed. The airplane then rolled to the right about three times in a manner he described as a wave, or vortex-like movement. He applied left aileron and lowered the flaps to 20 degrees, but the roll to the right was more severe. The pilot said the engine power was "good." He then noticed that the airplane was descending toward the ground, so he attempted to put the flaps completely down. His next memory was being outside the airplane after it collided with the ground. The airplane's information manual contains several pages of limitations and warnings about departing with even small amounts of frost, ice, snow, or slush on the airplane, as it adversely affects the airplane's flight characteristics. The manufacturer requires a visual or tactile inspection of the wings, and horizontal stabilizer to ensure they are free of ice or frost if the outside air temperature is below 10 degrees C, (50 degrees F), and notes that a heated hangar or approved deicing fluids should be used to remove ice, snow and frost accumulations. The weather conditions included clear skies, and a temperature of -11 degrees F. Post accident examination of the airplane revealed no observed mechanical malfunction. An examination of the engine revealed internal over-temperature damage, and minor external fire damage consistent with a massive spike of fuel flow at the time of ground impact. Damage to the propeller blades was consistent with high power at the time of ground impact. The rolling/vortex motion of the airplane was consistent with airframe contamination due to frost.

Flight / Schedule

Bethel - Hooper Bay - Scammon Bay

Registration

N5187B

MSN

208B-0270

Year of Manufacture

1991

Date

December 18, 2007 at 08:56 AM

Type

CRASH

Flight Type

Postal (mail)

Flight Phase

Takeoff (climb)

Crash Site

Airport (less than 10 km from airport)

Crash Location

Bethel Alaska

Region

North America • United States of America

Coordinates

60.7922°, -161.7558°

Crash Cause

Human factor

Narrative Report

On December 18, 2007 at 08:56 AM, Bethel - Hooper Bay - Scammon Bay experienced a crash involving Cessna 208B Grand Caravan, operated by Arctic Circle Air Service, with the event recorded near Bethel Alaska.

The flight was categorized as postal (mail) and the reported phase was takeoff (climb) at a airport (less than 10 km from airport) crash site.

2 people were known to be on board, 0 fatalities were recorded, 2 survivors were identified or estimated. This corresponds to an estimated fatality rate of 0.0%.

Crew on board: 1, crew fatalities: 0, passengers on board: 1, passenger fatalities: 0, other fatalities: 0.

The listed crash cause is human factor. About 0800, the commercial pilot did a preflight inspection of the accident airplane, in preparation for a cargo flight. Dark night, visual meteorological conditions prevailed. He indicated that the weather conditions were clear and cold, and frost was on the airplane. He said the frost was not bonded to the skin of the airplane, and he was able to use a broom to clean off the frost, resulting in a clean wing and tail surface. He reported that no deicing fluid was applied. After takeoff, he retracted the flaps to about 5 degrees at 110 knots of airspeed. The airplane then rolled to the right about three times in a manner he described as a wave, or vortex-like movement. He applied left aileron and lowered the flaps to 20 degrees, but the roll to the right was more severe. The pilot said the engine power was "good." He then noticed that the airplane was descending toward the ground, so he attempted to put the flaps completely down. His next memory was being outside the airplane after it collided with the ground. The airplane's information manual contains several pages of limitations and warnings about departing with even small amounts of frost, ice, snow, or slush on the airplane, as it adversely affects the airplane's flight characteristics. The manufacturer requires a visual or tactile inspection of the wings, and horizontal stabilizer to ensure they are free of ice or frost if the outside air temperature is below 10 degrees C, (50 degrees F), and notes that a heated hangar or approved deicing fluids should be used to remove ice, snow and frost accumulations. The weather conditions included clear skies, and a temperature of -11 degrees F. Post accident examination of the airplane revealed no observed mechanical malfunction. An examination of the engine revealed internal over-temperature damage, and minor external fire damage consistent with a massive spike of fuel flow at the time of ground impact. Damage to the propeller blades was consistent with high power at the time of ground impact. The rolling/vortex motion of the airplane was consistent with airframe contamination due to frost.

Aircraft reference details include registration N5187B, MSN 208B-0270, year of manufacture 1991.

Geospatial coordinates for this crash are approximately 60.7922°, -161.7558°.

Fatalities

Total

0

Crew

0

Passengers

0

Other

0

Crash Summary

About 0800, the commercial pilot did a preflight inspection of the accident airplane, in preparation for a cargo flight. Dark night, visual meteorological conditions prevailed. He indicated that the weather conditions were clear and cold, and frost was on the airplane. He said the frost was not bonded to the skin of the airplane, and he was able to use a broom to clean off the frost, resulting in a clean wing and tail surface. He reported that no deicing fluid was applied. After takeoff, he retracted the flaps to about 5 degrees at 110 knots of airspeed. The airplane then rolled to the right about three times in a manner he described as a wave, or vortex-like movement. He applied left aileron and lowered the flaps to 20 degrees, but the roll to the right was more severe. The pilot said the engine power was "good." He then noticed that the airplane was descending toward the ground, so he attempted to put the flaps completely down. His next memory was being outside the airplane after it collided with the ground. The airplane's information manual contains several pages of limitations and warnings about departing with even small amounts of frost, ice, snow, or slush on the airplane, as it adversely affects the airplane's flight characteristics. The manufacturer requires a visual or tactile inspection of the wings, and horizontal stabilizer to ensure they are free of ice or frost if the outside air temperature is below 10 degrees C, (50 degrees F), and notes that a heated hangar or approved deicing fluids should be used to remove ice, snow and frost accumulations. The weather conditions included clear skies, and a temperature of -11 degrees F. Post accident examination of the airplane revealed no observed mechanical malfunction. An examination of the engine revealed internal over-temperature damage, and minor external fire damage consistent with a massive spike of fuel flow at the time of ground impact. Damage to the propeller blades was consistent with high power at the time of ground impact. The rolling/vortex motion of the airplane was consistent with airframe contamination due to frost.

Cause: Human factor

Occupants & Outcome

Crew On Board

1

Passengers On Board

1

Estimated Survivors

2

Fatality Rate

0.0%

Known people on board: 2

Operational Details

Schedule / Flight

Bethel - Hooper Bay - Scammon Bay

Flight Type

Postal (mail)

Flight Phase

Takeoff (climb)

Crash Site

Airport (less than 10 km from airport)

Region / Country

North America • United States of America

Aircraft Details

Registration

N5187B

MSN

208B-0270

Year of Manufacture

1991