# NTSB ANC12CA016: Cessna 207A, N6480H, Kwigillingok, AK, December 21, 2011 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Data collection · Final report - Date: December 21, 2011, 10:20 local (14:20 UTC) - Place: Kwigillingok, AK - Coordinates: 59.876388, -163.168609 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=59.8764&lon=-163.1686&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach: VFR encounter with IMC](https://openairdocs.org/ntsb-events/401) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report April 2, 2012 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA Anchorage FSDO - NTSB case key (mKey): 82555 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC12CA016 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/82555/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=82555 - Page: https://openairdocs.org/ntsb/ANC12CA016 ## Probable cause The pilot’s decision to continue visual flight into instrument meteorological conditions with moderate icing, which resulted in structural icing and an aerodynamic stall. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Cessna 207A, 8 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=2073605), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible; cases with it: [Cessna 207A, 2 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=2073605), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md) - [Temp/humidity/pressure: conducive to structural icing](https://openairdocs.org/ntsb-findings/03031025): Environmental issues › Conditions/weather/phenomena · Effect on equipment; cases with it: [Cessna 207A, 1 case](https://openairdocs.org/ntsb-findings/03031025/cases.md?model=2073605), [All aircraft, 103 cases](https://openairdocs.org/ntsb-findings/03031025/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach: VFR encounter with IMC](https://openairdocs.org/ntsb-events/401) (defining event); cases with it: [Cessna 207A, 2 cases](https://openairdocs.org/ntsb-events/401/sequence.md?model=2073605), [All aircraft, 392 cases](https://openairdocs.org/ntsb-events/401/sequence.md) - [Approach: Structural icing](https://openairdocs.org/ntsb-events/210); cases with it: [Cessna 207A, 1 case](https://openairdocs.org/ntsb-events/210/sequence.md?model=2073605), [All aircraft, 102 cases](https://openairdocs.org/ntsb-events/210/sequence.md) - [Maneuvering: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241); cases with it: [Cessna 207A, 3 cases](https://openairdocs.org/ntsb-events/241/sequence.md?model=2073605), [All aircraft, 1,529 cases](https://openairdocs.org/ntsb-events/241/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Cessna 207A, 7 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=2073605), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that he was flying in visual meteorological conditions for most of the flight. As he approached the airport, he inadvertently entered an area of instrument meteorological conditions that resulted in a buildup of ice on the airframe and windscreen. He attempted to make a 180-degree turn to exit the conditions but was unable to maintain sufficient airspeed for flight, and the airplane descended and collided with terrain. The impact resulted in substantial damage to the fuselage, empennage, and wings. ## Factual narrative The pilot reported he was flying in visual meteorological conditions for most of the flight. As he approached the airport, he inadvertently entered an area of instrument meteorological conditions that resulted in a buildup of ice on the airframe and windscreen. He attempted to make a 180 degree turn to exit the conditions, but was unable to maintain sufficient airspeed for flight, and the airplane descended and collided with terrain. The impact resulted in substantial damage to the fuselage, empennage, and wings. ## Aircraft - Registration: [N6480H](https://openairdocs.org/deregistered/N6480H-2012-05-07), registration cancelled 2012-05-07, S/N 20700540, built 1979 (OpenAirDocs) - Reported make and model: CESSNA 207A - Registry model: [Cessna 207A](https://openairdocs.org/model/cessna-207a) (registry code 2073604) (OpenAirDocs) - Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 20700540 - Airframe hours: 11446 - Engines: CONT MOTOR IO 520 SERIES 285 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Operator: Flight Alaska Inc, doing business as Yute Air Alaska - Registered owner: Bethel Leasing LLC - Airworthiness certificate: Standard, Normal - Last inspection: Annual, December 11, 2011 - Departed: PABE, Bethel, AK - Destination: PAGG, Kwigillingok, AK - Flight plan: Company VFR - Airport: PAGG, Kwigillingok ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 44; injuries: minor; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review January 11, 2011; seat: left; flight hours: 2,500 total, 1,300 in this make and model, 234 in the last 90 days, 30 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Instrument (IMC), Day - Visibility: 1 statute miles - Lowest ceiling: 500 ft - Temperature: 21 °F, dew point 19 °F - Altimeter: 29.54 inHg - Observed at: PAKI, 26 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20111221029829A](https://openairdocs.org/incident/20111221029829A), Dec 21, 2011: Cessna 207A, Kwigillingok, AK, Substantial damage. On December 21, 2011 about 1100 Alaska standard time, (ast), a tricycle wheel equipped Cessna 207A airplane, N6480H, sustained substantial damage on approach… ## Other investigations on N6480H (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB SEA84LA147](https://openairdocs.org/ntsb/SEA84LA147), Jun 26, 1984: Cessna 207A (N6480H), Reno, NV, substantial damage ## Docket (1 files) The files NTSB released with the investigation on February 23, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=82555. 594 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 594 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40363191&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.