# NTSB SEA99LA050: Piper PA-18, N4036E, Boulder, MT, April 10, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 10, 1999, 12:30 local (18:30 UTC) - Place: Boulder, MT - Coordinates: 46.17073, -111.98928 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=46.1707&lon=-111.9893&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report June 22, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 46108 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA99LA050 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46108/pdf - Page: https://openairdocs.org/ntsb/SEA99LA050 ## Probable cause The pilot-in-command's failure to maintain directional control after encountering a dust-devil during landing rollout, resulting in a ground loop and collapse of the main landing gear. Factors include the dust-devil. ## Analysis The tailwheel airplane sustained substantial damage when it ground-looped after landing off-airport. The pilot stated that he was landing on a north-south dirt road to the south. He stated that the winds were calm and the airplane rolled into a dust devil and directional control was lost. He said there were no ruts or ditches on the road. The pilot reported that all his flight experience was in tailwheel airplanes ## Factual narrative On April 10, 1999, approximately 1230 mountain daylight time, N4036E, a Piper PA-18, sustained substantial damage when it ground-looped after landing off-airport near Boulder, Montana. The private pilot and his passenger were uninjured. The flight, conducted in visual meteorological conditions, had originated at Bozeman, Montana. There was no flight plan filed for the flight, and no report of the ELT actuating. The pilot stated that he was landing on a north-south dirt road to the south, near the Carey ranch, southeast of Boulder. He stated that the winds were calm and the airplane rolled into a dust devil and directional control was lost. He said there were no ruts or ditches on the road. The pilot reported that all his flight experience was in tailwheel airplanes, and did not report any mechanical malfunctions with the airplane. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - on ground/water, landing - roll - weather condition - dust devil/whirlwind (contributing factor) - directional control - not maintained, pilot in command (cause) - Main gear collapsed, landing - roll ## Aircraft - Registration: [N4036E](https://openairdocs.org/aircraft/N4036E), registered now, S/N 18-7809042, built 1977 (OpenAirDocs) - Reported make and model: Piper PA-18 - Registry model: [Piper PA-18-150](https://openairdocs.org/model/piper-pa-18-150) (registry code 7101828) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18-7809002 - Airframe hours: 4207 - Engines: Lycoming O-320-A2B 150 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Gerald M. Gaston - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, December 11, 1998, 15 hours before - Departed: BZN, BOZEMAN, MT ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 55; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; seat: front; flight hours: 4,152 total, 19 in this make and model, 4,152 as pilot in command, 34 in the last 90 days, 29 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Visibility: 30 statute miles - Lowest ceiling: none - Temperature: 50 °F - Altimeter: 29.00 inHg ## 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 19990410044749A](https://openairdocs.org/incident/19990410044749A), Apr 10, 1999: Piper PA18150, Carey Ranch, MT, No damage. (-23) Pilot stated that he encountered a "dirt devil" while touching down on a road. Ground loop followed, due to alleged sudden gust of wind. Accident… ## Other investigations on N4036E (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 WPR10CA469](https://openairdocs.org/ntsb/WPR10CA469), Sep 24, 2010: Piper PA-18-150 (N4036E), White Sulphur Springs, MT, substantial damage. Probable cause: The pilot's failure to maintain control of the airplane during a go-around in turbulent wind conditions, which resulted in a collision with trees. 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.