# NTSB WPR11CA041: Aviat A-1B, N178WW, Heber City, UT, November 6, 2010 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: November 6, 2010, 12:30 local (18:30 UTC) - Place: Heber City, UT - Coordinates: 40.334167, -111.297775 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.3342&lon=-111.2978&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Low altitude operation/event](https://openairdocs.org/ntsb-events/220) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report March 16, 2011 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Salt Lake FSDO - NTSB case key (mKey): 77754 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR11CA041 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/77754/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=77754 - Page: https://openairdocs.org/ntsb/WPR11CA041 ## Probable cause The pilot's failure to maintain clearance from the ground during low-level maneuvering in mountainous/hilly terrain. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: altitude](https://openairdocs.org/ntsb-findings/01062012): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Aviat A-1B, 4 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md?model=2210406), [All aircraft, 1,310 cases](https://openairdocs.org/ntsb-findings/01062012/cases.md) - [Wind: downdraft](https://openairdocs.org/ntsb-findings/03034035): Environmental issues › Conditions/weather/phenomena · Contributed to outcome; cases with it: [Aviat A-1B, 4 cases](https://openairdocs.org/ntsb-findings/03034035/cases.md?model=2210406), [All aircraft, 178 cases](https://openairdocs.org/ntsb-findings/03034035/cases.md) - [Terrain: mountainous/hilly terrain](https://openairdocs.org/ntsb-findings/03021010): Environmental issues › Physical environment · Not specified; cases with it: [Aviat A-1B, 3 cases](https://openairdocs.org/ntsb-findings/03021010/cases.md?model=2210406), [All aircraft, 329 cases](https://openairdocs.org/ntsb-findings/03021010/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-low-alt flying: Low altitude operation/event](https://openairdocs.org/ntsb-events/220) (defining event); cases with it: [Aviat A-1B, 2 cases](https://openairdocs.org/ntsb-events/220/sequence.md?model=2210406), [All aircraft, 780 cases](https://openairdocs.org/ntsb-events/220/sequence.md) ## Analysis The pilot reported that he was practicing the procedures for making approaches to back-country remote airstrips and was flying in approach configuration about 40 to 60 feet over a mountain ridge. Although the wind was light and variable, just as the airplane was crossing the ridge it encountered a downdraft, which resulted in a sudden loss of altitude. Before the pilot was able to correct the descent, one of the airplane's main landing gear tires came in contact with the snow-covered terrain, which resulted in the airplane slowing down and flipping over onto its back. The accident sequence resulted in damage to the top of the rudder and to one of the wing lift struts. The pilot reported no mechanical failures or malfunctions with the airplane at the time of the accident. ## Factual narrative The pilot reported that he was practicing the procedures for making approaches to back-country airstrips, and was flying in approach configuration about 40 to 60 feet over a mountain ridge. Although the wind was light and variable, just as the flight was crossing the ridge, the airplane encountered a downdraft which resulted in it suddenly losing altitude. The pilot stated that before he was able to correct the situation, one of the airplane's main gear tires came in contact with the snow-covered terrain, which resulted in the airplane slowing down and flipping over onto its back. The accident sequence resulted in damage to the top of the rudder and to one of the wing lift struts. The pilot reported no mechanical failures or malfunctions with the airplane at the time of the accident. ## Aircraft - Registration: [N178WW](https://openairdocs.org/aircraft/N178WW), registered now, S/N 2378, built 2006 (OpenAirDocs) - Reported make and model: AVIAT AIRCRAFT INC A-1B - Registry model: [Aviat A-1B](https://openairdocs.org/model/aviat-a-1b) (registry code 2210406) (OpenAirDocs) - Registry engine: [Lycoming IO-360-A1D6](https://openairdocs.org/engine/lycoming-io-360-a1d6) (registry code 41822, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 2378 - Airframe hours: 114 - Engines: LYCOMING IO-360-A1D6 200 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Stern Lessing S - Registered owner: Stern Lessing S - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 19, 2010 - Departed: 36U, Heber City, UT - Destination: 36U, Heber City, UT ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; injuries: none; airline transport; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, without waivers/limitations; flight hours: 3,833 total, 98 in this make and model ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 61 °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 20101106049349A](https://openairdocs.org/incident/20101106049349A), Nov 6, 2010: Aviat Aircr A-1B, Heber, UT, Substantial damage. According to the pilots statement, he made a decending circle over a valley adjacent to a ridge to check what the wind was doing. He circled back around to… ## Docket (1 files) The files NTSB released with the investigation on December 7, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=77754. 911 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 911 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40340020&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.