# NTSB ANC93LA046: Piper PA-22, N72999, Drift River, AK, March 20, 1993 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: March 20, 1993, 11:23 local (15:23 UTC) - Place: Drift River, AK - Coordinates: 61.080032, -151.160171 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=61.0800&lon=-151.1602&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report May 17, 1994 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 2331 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC93LA046 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/2331/pdf - Page: https://openairdocs.org/ntsb/ANC93LA046 ## Probable cause THE PILOTS INADVERTENT VFR FLIGHT INTO IMC CONDITIONS. FACTORS WERE THE RISING TERRAIN AND THE WHITEOUT CONDITIONS. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with terrain/water, climb - terrain condition - rising (contributing factor) - vfr flight into imc - inadvertent, pilot in command (cause) - lack of familiarity with geographic area, pilot in command - weather condition - whiteout (contributing factor) - Nose over, other - terrain condition - rough/uneven ## Analysis DURING THE PILOT'S FIRST ATTEMPT TO FLY THROUGH LAKE CLARK PASS, HE MISTAKENLY TURNED UP THE WRONG VALLEY. WHEN THE ALREADY POOR FLIGHT VISIBILITY CONTINUED TO DETERIORATE, HE BEGAN A 180 DEGREE TURN TO GET OUT OF THE VALLEY, DURING WHICH HE ENTERED WHITEOUT CONDITIONS. WHEN HE SAW MOUNTAINS ON BOTH SIDES, HE KNEW THAT HE HAD MISSED THE TURN OUT OF THE VALLEY. WITH NO DEPTH PERCEPTION ON WHICH TO ESTIMATE HIS ALTITUDE ABOVE THE GROUND, HE APPLIED FULL ENGINE POWER AND MAINTAINED THE BEST CLIMB ATTITUDE. VERY SOON AFTERWARD THE AIRPLANE COLLIDED WITH, AND NOSED OVER ON, A GLACIER. DURING THE PREFLIGHT WEATHER BRIEFING THE PILOT WAS TOLD THAT LAKE CLARK PASS WAS FORECAST TO BE MARGINAL VFR TO IFR. ## Factual narrative HISTORY OF FLIGHT On March 20, 1993, at 1123 Alaska standard time, a wheel equipped Piper PA 22 airplane, N72999, encountered whiteout snow conditions, then nosed over after making a controlled crash landing on a glacier approximately 20 miles southwest of Drift River, Alaska. The commercial pilot, the sole occupant, was not injured, and the airplane was substantially damaged. The personal flight, operating under 14 CFR Part 91, departed Palmer, Alaska at 0938, and was destined for King Salmon, Alaska. Instrument meteorological conditions existed, and a VFR flight plan was filed. Following the accident the pilot stated the following in part: "I was planning to fly through Lake Clark Pass en route to King Salmon, but missed my turn and flew up into the wrong valley. The ceiling and visibility kept getting lower so I decided to turn back. After doing a 180 degree turn the ceiling to my front was even lower, and the visibility was much lower because of the snow. So I decided to land on the glacier. Then I encountered whiteout snow conditions and lost all depth perception. I could still see about 3 miles up into the valley over the glacier. I touched down in snow about 2 feet deep, and the airplane nosed over onto it's back. I got a weather briefing by telephone about 45 minutes before taking off, from the automated flight service station in Kenai, Alaska. Marginal VFR conditions and turbulence was forecast. This was the first time I had tried to fly through the mountains this way. I guess I just used poor judgement." METEOROLOGICAL INFORMATION According to FAA records, at 0817 the pilot of N72999 telephoned the FAA Automated Flight Service Station (AFSS) in Kenai, Alaska, and obtained a weather briefing, then filed a VFR flight plan to King Salmon. During the briefing the pilot was told that the forecast (valid until 1800) called for Lake Clark Pass (elevation 1,000 feet above mean sea level) conditions to be marginal VFR to IFR. Ceilings in the Palmer, Anchorage and Kenai area were forecast to be below 1,000 feet and the visibility below 3 miles. Lower ceilings and visibility was forecast along and in the mountains. ## Aircraft - Registration: [N72999](https://openairdocs.org/aircraft/N72999), registered now, S/N 22-6507 (OpenAirDocs) - Reported make and model: PIPER PA-22 - Registry model: [Piper PA-22-160](https://openairdocs.org/model/piper-pa-22-160) (registry code 7102214) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 22-6507 - Airframe hours: 3095 - Engines: LYCOMING O-320-A2B 150 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Johnson, Ronald B. - Registered owner: Johnson, Ronald B. - Airworthiness certificate: Standard, Normal - Last inspection: Annual, January 18, 1993, 10 hours before - Departed: AK01, PALMER, AK - Destination: AKN, KING SALMON, AK - Flight plan: VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 42; commercial; airplane ratings: single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 484 total, 125 in this make and model, 395 as pilot in command, 18 in the last 90 days, 10 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Instrument (IMC), Day - Wind: 45° at 12 knots - Visibility: 3 statute miles - Lowest ceiling: 4,500 ft overcast - Temperature: 19 °F ## 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 19930320005779A](https://openairdocs.org/incident/19930320005779A), Mar 20, 1993: Piper PA22160, Drift River, AK, Substantial damage. Flew into low ceiling and whiteout IMC. Nosed over in deep snow on a glacier. Was advised prior VFR not recommended ## Other investigations on N72999 (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 GAA17CA187](https://openairdocs.org/ntsb/GAA17CA187), Feb 16, 2017: Piper PA22 (N72999), Ruby, AK, substantial damage. Probable cause: The pilot’s failure to maintain directional control while landing in flat light conditions on a hard-packed snow-covered landing area. 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.