# NTSB SEA98LA080: Air Tractor AT-401, N1009T, Idaho Falls, ID, May 20, 1998 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: May 20, 1998, 09:15 local (15:15 UTC) - Place: Idaho Falls, ID - Coordinates: 43.429809, -111.890449 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.4298&lon=-111.8904&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report July 12, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 42789 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA98LA080 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/42789/pdf - Page: https://openairdocs.org/ntsb/SEA98LA080 ## Probable cause The pilot's failure to maintain clearance from a power transmission line during an aerial application flight. Factors include a power line located just beyond the boundary of the field being sprayed, and the pilot's incorrect judgement of the distance between the wire and his aircraft. ## Analysis According to the pilot, who was maneuvering near the power line while applying chemicals to a field, he had just rolled wings-level and descended for another pass when his left wing contacted the top wire of the power line. He said that he saw the line and thought he had clearance, but the aircraft's wing caught the wire near its tip. He reported that after colliding with the power line, the aircraft struck the ground in a 'cart-wheeling' motion. He further stated that he was accustomed to flying the AT-300, but that he had recently purchased the AT-401, and that this was his first application flight using the new aircraft. It was his opinion that the different size and sight-picture of the 401 had caused him to think he had more clearance from the wire than he actually had. ## Factual narrative On May 20, 1998, approximately 0915 mountain daylight time, an Air Tractor AT-401, N1009T, collided with a power transmission line during an aerial application flight about two miles northwest of Idaho Falls, Idaho. The commercial pilot, who was the sole occupant, received minor injuries, and the aircraft, which was owned and operated by the pilot, sustained substantial damage. The 14 CFR Part 137 flight, which originated at an agricultural airstrip near Osgood, Idaho, was being operated in visual meteorological conditions. According to the pilot, who had been maneuvering near the power line while applying chemicals to a field, he was just rolling wings-level and descending for another pass when his left wing contacted the top wire of a power line located just beyond the boundary of the field he was spraying. He said that he saw the line and thought he had clearance, but the aircraft's wing caught the wire near its tip. He reported that after colliding with the power line, the aircraft struck the ground in a "cart-wheeling" motion. He further stated that he was accustomed to flying the AT-300, but that he had recently purchased the AT-401, and that this was his first application flight using the new aircraft. It was his opinion that the different size and sight-picture of the 401 had caused him to think he had more clearance from the wire than he actually had. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with object, maneuvering - clearance - not maintained, pilot in command (cause) - distance - misjudged, pilot in command (contributing factor) - object - wire,transmission (contributing factor) ## Aircraft - Registration: [N1009T](https://openairdocs.org/deregistered/N1009T-2006-12-08), registration cancelled 2006-12-08, S/N 401-0707, built 1989 (OpenAirDocs) - Reported make and model: Air Tractor AT-401 - Registry model: [Air Tractor AT-401](https://openairdocs.org/model/air-tractor-at-401) (registry code 0390204) (OpenAirDocs) - Registry engine: [Pratt & Whitney R1340 series](https://openairdocs.org/engine/pratt-whitney-r1340-series) (registry code 52016, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 401-0707 - Airframe hours: 4055 - Engines: P&W 1340-AN2 600 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Orlin D. Lewis - Airworthiness certificate: Special, Restricted (Special) - Last inspection: 100 hour, April 21, 1998, 9 hours before - Departed: OSGOOD, ID ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 53; commercial, flight instructor; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: center; flight hours: 9,882 total, 9 in this make and model, 9,761 as pilot in command, 12 in the last 90 days, 9 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 50° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 50 °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 19980520010249A](https://openairdocs.org/incident/19980520010249A), May 20, 1998: Airtrc AT401, Idaho Falls, ID, Substantial damage. Acft struck a power line during aerial application, Idaho Falls, ID. (.4) according to the pilot, who was maneuvering near the power line while applying… ## Other investigations on N1009T (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB DEN93LA081](https://openairdocs.org/ntsb/DEN93LA081), Jul 15, 1993: Air Tractor AT-401 (N1009T), Dermott, AR, substantial damage. Probable cause: POWER LOSS DUE TO THE TOTAL FAILURE OF THE ENGINE'S MASTER ROD. FACTORS WERE AN IMPROPER ENGINE OVERHAUL AND THE LACK OF SUITABLE TERRAIN FOR A FORCED LANDING. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; 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.