# NTSB GAA19CA369: Piper L21, N753AT, Imnaha, OR, June 21, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: June 21, 2019, 15:00 local (22:00 UTC) - Place: Imnaha, OR - Coordinates: 45.666389, -116.618331 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=45.6664&lon=-116.6183&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report June 29, 2020 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - NTSB case key (mKey): 99699 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA19CA369 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99699/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=99699 - Page: https://openairdocs.org/ntsb/GAA19CA369 ## Probable cause The pilot's failure to maintain directional control while taking off from a soft, rough field, which resulted in a ground-loop. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters: directional control](https://openairdocs.org/ntsb-findings/01062020): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Piper L-21B, 4 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md?model=7101815), [All aircraft, 3,958 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Piper L-21B, 4 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=7101815), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Terrain: rough terrain](https://openairdocs.org/ntsb-findings/03021015): Environmental issues › Physical environment · Effect on operation (probable cause); cases with it: [Piper L-21B, 1 case](https://openairdocs.org/ntsb-findings/03021015/cases.md?model=7101815), [All aircraft, 442 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md) - [Runway/land/takeoff/taxi surface: soft surface](https://openairdocs.org/ntsb-findings/03023020): Environmental issues › Physical environment · Effect on operation (probable cause); cases with it: [Piper L-21B, 1 case](https://openairdocs.org/ntsb-findings/03023020/cases.md?model=7101815), [All aircraft, 264 cases](https://openairdocs.org/ntsb-findings/03023020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [Piper L-21B, 4 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=7101815), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) - [Takeoff: Abnormal runway contact](https://openairdocs.org/ntsb-events/090); cases with it: [Piper L-21B, 1 case](https://openairdocs.org/ntsb-events/090/sequence.md?model=7101815), [All aircraft, 1,506 cases](https://openairdocs.org/ntsb-events/090/sequence.md) ## Analysis The pilot reported that, during takeoff from a soft field, the airplane veered left then began to bounce as it went over soft and rough ground. He tried to steer the airplane back toward the runway and abort the takeoff, but the airplane continued to bounce sideways, which resulted in a ground-loop. The airplane sustained substantial damage to the left elevator. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. ## Factual narrative The pilot of the tailwheel equipped airplane reported that, during takeoff from a soft field, the airplane veered left then began to bounce as it went over soft and rough ground. He tried to steer the airplane back towards the runway and abort the takeoff, but the airplane continued to bounce sideways which resulted in a ground loop. The airplane sustained substantial damage to the left elevator. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. ## Aircraft - Registration: [N753AT](https://openairdocs.org/aircraft/N753AT), registered now, S/N 18-3377, built 1954 (OpenAirDocs) - Reported make and model: Piper L21 (B) - Registry model: [Piper L-21B](https://openairdocs.org/model/piper-l-21b) (registry code 7101815) (OpenAirDocs) - Registry engine: [Lycoming O-360-C2A](https://openairdocs.org/engine/lycoming-o-360-c2a) (registry code 42285, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18-3377 - Year built: 1954 - Airframe hours: 487.4 - Engines: Lycoming O-360-C2A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: L-Bird LLC - Registered owner: L-Bird LLC - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 26, 2019 - Departed: 1DA, Lucile, ID - Destination: OR9, Imnaha, OR - Airport: OR9, Lord Flat, runway 01, 1,728 × 15 ft, grass/turf - Equipment: Satellite tracking device, Electronic multifunction display, ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 58; injuries: none; private; airplane ratings: single-engine land, multi-engine sea, multi-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review May 20, 2019; seat: front; restraint: 4-point; flight hours: 5,694 total, 80 in this make and model, 5,694 as pilot in command, 91 in the last 90 days, 49 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Visibility: 2 statute miles - Observed at: KGIC, 27 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 20190621007689A](https://openairdocs.org/incident/20190621007689A), Jun 21, 2019: Piper L-21B, Imnaha, OR, Substantial damage. Pilot landed at Lord Flat, Oregon and shutdown. On takeoff, the wheels contacted a rut on the grass runway and the aircraft started to move from side to side… ## Docket (2 files) The files NTSB released with the investigation on May 5, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=99699. 1.3 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483430&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Accident Photo (item 2, .PDF, 238 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40483431&FileExtension=.PDF&FileName=Accident%20Photo-Master.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.