# NTSB ANC94LA039: Cessna 170B, N4310B, Chugiak, AK, March 7, 1994 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: March 7, 1994, 15:15 local (19:15 UTC) - Place: Chugiak, AK - Coordinates: 61.410858, -149.170837 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=61.4109&lon=-149.1708&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 4 uninjured - Status: Completed, report January 12, 1995 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 2489 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC94LA039 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/2489/pdf - Page: https://openairdocs.org/ntsb/ANC94LA039 ## Probable cause THE PILOT-IN-COMMAND'S IMPROPER INFLIGHT DECISION MAKING. FACTORS CONTRIBUTING TO THE ACCIDENT WERE THE MOUNTAINOUS TERRAIN AND THE DOWNDRAFT WEATHER 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 - mountainous/hilly (contributing factor) - in-flight planning/decision - improper, pilot in command (cause) - weather condition - downdraft (contributing factor) ## Analysis THE PILOT SAID HE ATTEMPTED TO FLY 'UP VALLEY' WHEN HE ENCOUNTERED DOWNDRAFTS. HE APPLIED FULL POWER TO MAINTAIN ALTITUDE BUT DID NOT HAVE ENOUGH AIRSPEED TO TURN OUT OF THE VALLEY. UNABLE TO MANEUVER OUT OF THE VALLEY THE PILOT MADE A LANDING IN DEEP SNOW ON A STEEP INCLINE AT THE 3000 FT LEVEL, 100 FEET BELOW THE RIDGE LINE. ## Factual narrative On March 7, 1994, at approximately 1515 Alaska standard time, a wheel-equipped Cessna 170B airplane, N4310B, collided with mountainous terrain while attempting to out climb a downdraft in a valley eight miles east of Birchwood Airport, Chugiak, Alaska. The airplane departed the Birchwood Airport at approximately 1500 on a local flight for personal reasons. No flight plan was on file for the flight conducted under 14 CFR Part 91 in visual meteorological conditions. The private pilot and his three passengers were not injured and the airplane sustained substantial damage. The pilot told the NTSB and an FAA inspector that he encountered a mountain downdraft as he climbed southbound in the valley which forced him into a controlled collision with the snow-covered ridge. He said that he had been flying with his wife and two children on a local sightseeing flight when the force of the wind exceeded his aircraft's ability to avoid a collision with the terrain. He told investigators that he had checked the weather by "listening on the Big Lake VOR;" however, he could not recall the forecast or observation at the time of the interview. The impact occurred at the 2,900 foot level of a 3,000 foot ridge. Following the impact with the snow-covered ridge, the family waited at the wreckage until a passing snowmobile driver sighted them and brought them to safety. The pilot said that while awaiting rescue, the winds were from the south at 25 knots with higher gusts. In a written statement from the pilot the NTSB learned that the pilot had attempted to fly the airplane "up valley," when at the halfway point, he said that he encountered severe down drafts, applied full power to maintain altitude but did not have enough airspeed to attempt a turn out of the valley. After continuing in up drafts and downdrafts the pilot made a forced landing in deep snow and a steep incline at the 3000 foot level, 100 feet below the ridge line. ## Aircraft - Registration: [N4310B](https://openairdocs.org/aircraft/N4310B), registered now, S/N 26654, built 1955 (OpenAirDocs) - Reported make and model: CESSNA 170B - Registry model: [Cessna 170B](https://openairdocs.org/model/cessna-170b) (registry code 2072306) (OpenAirDocs) - Registry engine: [Continental 0-300 series](https://openairdocs.org/engine/continental-0-300-series) (registry code 17022, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 26654 - Airframe hours: 3541 - Engines: CONTINENTAL O-300A 145 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Michael A. Petrie - Registered owner: Michael & Linda Petrie - Airworthiness certificate: Standard, Normal - Last inspection: Annual, May 3, 1993, 73 hours before ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 37; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; seat: left; flight hours: 564 total, 470 in this make and model, 510 as pilot in command, 4 in the last 90 days, 4 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 180° at 25 knots, gusting 15 - Visibility: 25 statute miles - Temperature: 27 °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 19940307003879A](https://openairdocs.org/incident/19940307003879A), Mar 7, 1994: Cessna 170B, Birchwood, AK, Substantial damage. Unable to outclimb rising terrain in a valley due to strong surface wind and downdraft. Landed in deep snow. 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.