PORT HEIDEN, AK, USA
N9316F
Cessna 208A
The pilot departed in visual meteorological conditions of three to four miles visibility with high ceilings. He stated the airplane encountered freezing rain about five miles south of the airport while in cruise flight at 1,200 feet msl, and rapidly accumulated ice on the airframe, wings, and windshield. The pilot said he initially changed altitude in an attempt to exit the icing conditions. Ice accumulation continued, so he elected to return. While maneuvering to land at the airport, the airplane was unable to maintain altitude at full engine power. He said that any angle of bank resulted in the onset of prestall buffet, so he decided to land on a frozen lake south of the airport. He said that the airplane did not reach the lake, 'mushed into the ground,' and during the flare/touchdown, the left wing stalled. The pilot did not have access to the official weather prior to departure. The National Weather Service contracted observer, made his observation from a location about five miles south of the official weather station at the airport. The FAA AWOS-3 was inoperative. Examination of the airplane after the accident revealed a 1/2 inch layer of clear ice covering all the upper and lower airfoil surfaces of the airplane, from leading edges to between 1/3 and 1/2 of the chords. All antennas were coated with approximately 1/2 inch of clear ice. The airplane was not equipped with ice protection equipment except for pitot heat and windshield heat.
On January 30, 1998, at 1700 Alaska standard time, a Cessna 208A airplane, N9316F, was destroyed when it impacted frozen tundra, about one mile southwest of the Port Heiden Airport, Port Heiden, Alaska. The airline transport pilot received minor injuries. The airplane was operated by Peninsula Airways, Inc., of Anchorage, Alaska. The flight departed at 1700, and was conducted under 14 CFR Part 135 as a nonscheduled cargo flight from Port Heiden southbound to Chignik, Alaska. During a telephone interview with the NTSB investigator-in-charge (IIC) at 1700 on February 3, 1998, the pilot reported departing in visual meteorological conditions of three to four miles visibility with high ceilings. He stated the airplane encountered freezing rain about five miles south of the airport while in cruise at 1,200 feet msl, and rapidly accumulated ice on the airframe, wings, and windshield. The pilot said he initially changed altitude in an attempt to exit the icing conditions. Ice accumulation continued, so he elected to return to Port Heiden. While maneuvering to land at the airport, the airplane was unable to maintain altitude while at full engine power. The pilot related that any angle of bank resulted in the onset of prestall buffet. He stated that he decided to land on a frozen lake south of the airport. He said that the airplane did not reach the lake, "mushed into the ground," and that when he attempted to flare to land, the left wing stalled. He said the airplane was not equipped with deice boots, nor propeller anti-ice. It was equipped with an electrically heated windshield, which the pilot indicated was melting ice into slush. The pilot noted that he was unable to see through the windshield. Postaccident testing of the electric windshield heat revealed no discrepancies. Photographs taken immediately after the accident, and postaccident inspection by two FAA inspectors on February 4, 1998, revealed a 1/2 inch layer of clear ice covering all the upper and lower airfoil surfaces of the airplane, from leading edges to between 1/3 and 1/2 of the chords. All antennas were coated with approximately 1/2 inch of clear ice. No terminal weather forecast is available for Port Heiden. The Area Forecast valid for the time of the accident did not include freezing precipitation. Weather observations for Port Heiden are obtained from a part-time certified weather observer under contract to the National Weather Service (NWS). This individual has calibrated observation instruments which are contractually required to be located at the airport. After recording the weather, the observer sends the information via modem to the NWS. This weather is then available to anyone with access to NWS data, normally within five minutes of the observation. The 1553 NWS data base observation indicates light snow. Light snow is not entered on the observer's "Surface Weather Observations (Metar/Speci)" form at 1545. The weather observation for Port Heiden, entered into the NWS data base at 1653 was: visibility of one mile in -SN (light snow), vertical visibility of 100 feet, temperature minus 7 degrees C. The observation entered on the observer's "Surface Weather Observations (Metar/Speci)" form at 1645, submitted to the NWS, indicated -SNFZDL (light snow and freezing drizzle), and a vertical visibility of 200 feet. The observer's "Surface Weather Observations (Metar/Speci)" form contains an entry for a SPECI (special observation) at 1705 of one mile visibility, light snow and freezing drizzle, and a vertical visibility of 100 feet. No special observation is in the NWS data base. The next recorded observation is at 1945. The pilot stated the departure weather was high ceilings, three miles visibility, and light precipitation. The station manager who helped load the airplane, stated the weather at the time of departure (1650) was 600 to 700 feet overcast, 3 to 4 miles visibility, and light precipitation. Both of these individuals said they observed the weather observer depart the airport about 1630. The station manager told two FAA inspectors that the weather observer did not return to the airport until about 1715. The observer told these FAA inspectors that he took weather observations from his home, about five miles south of the airport, and that he had the equipment there to do so. A review of the NWS contract for this station indicated the required calibrated equipment is located at the observer's office at the airport. Interviews with NWS managers revealed that weather observations are not valid if not taken from the specified geographic location. On the date of the accident, the 37th edition of the Kodiak VFR sectional chart, valid until February 28, 1998, depicted an automated weather observation station (AWOS-3) to be available at Port Heiden on frequency 124.4 Mhz. Interviews between the NTSB investigator and both NWS managers and company pilots revealed that this station was not commissioned. Weather information was not available on this frequency, nor had it ever been. The 38th edition of this chart did not depict this AWOS-3 station. 14 CFR 135.213 states in part, "(a) Whenever a person operating an aircraft under this part is required to use a weather report..., that person shall use that of the U.S. National Weather Service, or a source approved by the National Weather Service... . However... the pilot in command may, if such a report is unavailable, use ... that pilot's own observations... ."
The pilot's inadequate in-flight decision resulting in airframe ice accumulation to the extent that degraded aircraft performance and insufficient airspeed occurred followed by a stall. Contributing factors were freezing rain and icing conditions.
Source: NTSB Aviation Accident Database
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