# NTSB ANC01LA029: Piper PA-18, N2191J, Anchorage, AK, January 13, 2001 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: January 13, 2001, 14:30 local (18:30 UTC) - Place: Anchorage, AK - Coordinates: 61.232223, -151.07611 - Nearby events: https://openairdocs.org/map.md?lat=61.2322&lon=-151.0761&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report August 21, 2001 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA, Anchorage FSDO - NTSB case key (mKey): 50931 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC01LA029 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/50931/pdf - Page: https://openairdocs.org/ntsb/ANC01LA029 ## Probable cause The pilot's improper use of the carburetor heat control. Factors in the accident were the presence of carburetor icing conditions, and snow-covered terrain that was unsuitable for a forced landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - nonmechanical, cruise - weather condition - carburetor icing conditions (contributing factor) - carburetor heat - improper use of, pilot in command (cause) - Forced landing, emergency descent/landing - terrain condition - none suitable (contributing factor) - On ground/water encounter with terrain/water, emergency descent/landing - terrain condition - snow covered (contributing factor) - Nose over, emergency descent/landing ## Analysis The private certificated pilot was in cruise flight about 1,000 feet above ground level (agl). He observed an area of snow showers ahead of the airplane, and decided to descend to about 500 feet agl. The pilot said he reduced the engine throttle without first applying carburetor heat. When he added engine throttle to level the airplane at 500 feet, the engine began sputtering. He then applied carburetor heat, but the engine did not respond. The engine continued to run rough, and the airplane could not sustain level flight. The pilot selected a snow-covered gravel bar for a forced landing. The airplane touched down in snow that was about 18 inches deep. During the landing roll, the airplane nosed over, and received damage to the right wing lift strut and the rudder. The pilot reported the weather conditions in the area of the accident as 1,200 to 1,500 feet overcast; temperature 35 to 38 degrees F; light to moderate snow showers. According to published carburetor icing charts, the atmospheric conditions at the time of the accident (38 degrees and visible moisture) reflected the probability of serious icing utilizing descent power. A postaccident inspection disclosed no mechanical anomalies with the engine. ## Factual narrative On January 13, 2001, about 1430 Alaska standard time, a tundra tire-equipped Piper PA-18 airplane, N2191J, sustained substantial damage during a forced landing, about 32 miles west of Anchorage, Alaska. The airplane was being operated as a visual flight rules (VFR) local area personal flight when the accident occurred. The airplane was operated by the pilot. The private certificated pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed. The flight originated at the Birchwood Airport, Chugiak, Alaska, about 1330. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), January 14, 2001, the pilot reported that he was in cruise flight about 1,000 feet above ground level (agl). He observed an area of snow showers ahead of the airplane, and decided to descend to about 500 feet agl. The pilot said he reduced the engine throttle without first applying carburetor heat. When he added engine throttle to level the airplane at 500 feet, the engine began sputtering. He then applied carburetor heat, but the engine did not respond. The engine continued to run rough, and the airplane could not sustain level flight. The pilot selected a snow-covered gravel bar for a forced landing. The airplane touched down in snow that was about 18 inches deep. During the landing roll, the airplane nosed over, and received damage to the right wing lift strut and the rudder. At 1453, an Aviation Routine Weather Report (METAR) at Anchorage was reporting in part: Wind, 276 degrees at 7 knots; visibility, 10 statute miles; clouds and sky condition, few at 2,500 feet, 7,000 feet overcast; temperature, 29 degrees F; dew point, 27 degrees F; altimeter, 29.52 inHg. In the Pilot/Operator report (NTSB Form 6120.1/2) submitted by the pilot, he reported the weather conditions in the area of the accident as 1,200 to 1,500 feet overcast; temperature 35 to 38 degrees F; light to moderate snow showers. The owner's handbook for the accident airplane states in part: "Cruising: ...Unless icing conditions in the carburetor are severe, do not cruise with the carburetor heat on. Apply full carburetor heat only for a few seconds at intervals determined by icing severity. Approach and Landing: ...The carburetor heat need not be used unless icing conditions prevail, but the engine should be cleared occasionally by opening the throttle." The FAA's, Pilot's Handbook of Aeronautical Knowledge, AC 61-23C, states, in part: "Conditions conducive to carburetor icing: ...if the temperature is between 20 degrees F and 70 degrees F, with visible moisture or high relative humidity, the pilot should be constantly on the alert for carburetor ice. During low or closed throttle settings, an engine is particularly susceptible to carburetor icing." The FAA's, Pilot Precautions and Procedures to be Taken in Preventing Aircraft Reciprocating Engine Induction System and Fuel System Icing Problems, AC 20-113, states, in part: Vaporization icing may occur at temperatures from 32 degrees F to as high as 100 degrees F with a relative humidity of 50 percent or above… Since aviation weather reports normally include air temperature and dew point temperature, it is possible to relate the temperature/dew point spread to relative humidity. As the spread becomes less, relative humidity increases and becomes 100 percent when temperature and dew point are the same. In general, when the temperature/dew point spread reaches 20 degrees or less, you have a relative humidity of 50 percent or higher and are in potential icing conditions." According to published carburetor icing charts, the atmospheric conditions at the time of the accident (38 degrees and visible moisture) reflected the probability of serious icing utilizing descent power. In a telephone conversation with the pilot on June 11, 2001, he reported that no mechanical malfunctions were found after the airplane was recovered. ## Aircraft - Registration: [N2191J](https://openairdocs.org/aircraft/N2191J), registered now, S/N 18-7185, built 1960 (OpenAirDocs) - Reported make and model: Piper PA-18 - Registry model: [Piper PA-18A 150](https://openairdocs.org/model/piper-pa-18a-150) (registry code 7101837) (OpenAirDocs) - Registry engine: [Lycoming O-320-A2B](https://openairdocs.org/engine/lycoming-o-320-a2b) (registry code 42101, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18-7185 - Airframe hours: 4000 - Engines: Lycoming O-320 150 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Eric J. Jackson - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 24, 2000, 40 hours before - Departed: PABV, Chugiak, AK ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 37; injuries: none; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; last flight review September 7, 1999; seat: left; flight hours: 362 total, 35 in this make and model, 10 in the last 90 days, 5 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 276° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: 7,000 ft overcast - Temperature: 28 °F, dew point 27 °F - Altimeter: 29.52 inHg - Observed at: PANC, 32 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 20010113039709A](https://openairdocs.org/incident/20010113039709A), Jan 13, 2001: Piper PA18A150, Eagle River, AK, Substantial damage. (-23) On January 13th 2001 the pilot of super cub N2191J was conducting a pleasure flight in the olsen creek area. In preparation for losing some altitude the… 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.