# NTSB GAA15CA251: Air Tractor AT 402A, N321DA, Fort Pierre, SD, September 4, 2015 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Data collection · Final report - Date: September 4, 2015, 07:55 local (13:55 UTC) - Place: Fort Pierre, SD - Coordinates: 44.376667, -100.631385 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=44.3767&lon=-100.6314&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Controlled flight into terr/obj (CFIT)](https://openairdocs.org/ntsb-events/120) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report October 8, 2015 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA Rapid City FSDO - NTSB case key (mKey): 91942 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA15CA251 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/91942/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=91942 - Page: https://openairdocs.org/ntsb/GAA15CA251 ## Probable cause The pilot's failure to maintain obstacle clearance, which resulted in the airplane striking guy-wires during aerial application operations. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Attention/monitoring: task monitoring/vigilance](https://openairdocs.org/ntsb-findings/02021520): Personnel issues › Psychological · Pilot (probable cause); cases with it: [Air Tractor AT-402A, 1 case](https://openairdocs.org/ntsb-findings/02021520/cases.md?model=0390206), [All aircraft, 330 cases](https://openairdocs.org/ntsb-findings/02021520/cases.md) - [Fuselage: fuselage main structure](https://openairdocs.org/ntsb-findings/01035310): Aircraft › Aircraft structures · Damaged/degraded (probable cause); cases with it: [Air Tractor AT-402A, 1 case](https://openairdocs.org/ntsb-findings/01035310/cases.md?model=0390206), [All aircraft, 24 cases](https://openairdocs.org/ntsb-findings/01035310/cases.md) - [Object/animal/substance: tower/antenna (incl guy wires)](https://openairdocs.org/ntsb-findings/03022017): Environmental issues › Physical environment · Effect on equipment; cases with it: [Air Tractor AT-402A, 2 cases](https://openairdocs.org/ntsb-findings/03022017/cases.md?model=0390206), [All aircraft, 55 cases](https://openairdocs.org/ntsb-findings/03022017/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Controlled flight into terr/obj (CFIT)](https://openairdocs.org/ntsb-events/120) (defining event); cases with it: [Air Tractor AT-402A, 2 cases](https://openairdocs.org/ntsb-events/120/sequence.md?model=0390206), [All aircraft, 1,074 cases](https://openairdocs.org/ntsb-events/120/sequence.md) - [Maneuvering: Attempted remediation/recovery](https://openairdocs.org/ntsb-events/060); cases with it: [Air Tractor AT-402A, 2 cases](https://openairdocs.org/ntsb-events/060/sequence.md?model=0390206), [All aircraft, 1,422 cases](https://openairdocs.org/ntsb-events/060/sequence.md) - [Maneuvering: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Air Tractor AT-402A, 2 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=0390206), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot reported that after conducting a pass over a field during an aerial application flight, he passed clear of a tower but did not see the tower support guy-wires and collided with them. He stated, "After the guy-wire impact there was an immediate sound of the engine starting to lose power and/or shut down." The pilot then performed an emergency landing on a gravel road without further incident. A post flight inspection revealed substantial damage to the fuselage and left wing. The pilot reported there were no pre-impact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. ## Factual narrative The pilot reported that after conducting a pass over a field during an aerial application flight, he passed clear of a tower but did not see the tower support guy-wires and collided with them. He stated, "After the guy-wire impact there was an immediate sound of the engine starting to lose power and/or shut down." The pilot then performed an emergency landing on a gravel road without further incident. A post flight inspection revealed substantial damage to the fuselage and left wing. The pilot reported there were no pre-impact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. ADDITIONAL INFORMATION Aviation Life Support Systems The pilot reported that he was wearing a Gentex Corporation HGU-55/E helmet for the flight. He stated, "The face shield/visor protected my eyes and upper face from impact injuries of the windshield/miscellaneous debris and also from engine oil." He also stated that, "The helmet itself protected my head from physical injury." The helmet sustained no noticeable damage from the accident. The Air Tractor AT-402 airplane flight manual states the following placard must be displayed, "Occupant must attach seatbelt and shoulder harness and wear a DOT approved or mil-spec crash helmet." ## Aircraft - Registration: [N321DA](https://openairdocs.org/aircraft/N321DA), registered now, S/N 402A-0814, built 1991 (OpenAirDocs) - Reported make and model: AIR TRACTOR INC AT 402A (A) - Registry model: [Air Tractor AT-402A](https://openairdocs.org/model/air-tractor-at-402a) (registry code 0390206) (OpenAirDocs) - Registry engine: [Pratt & Whitney Canada PT6A-15AG](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-15ag) (registry code 52246, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 402A-0814 - Year built: 1991 - Airframe hours: 9401.6 - Engines: Pratt & Whitney PT6A-15AG 680 horsepower turbo prop - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Randy A. Yost / Barbara J. Yost - Registered owner: Randy A. Yost / Barbara J. Yost - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, January 10, 2015 - Departed: SD21, HAYES, SD - Destination: SD21, HAYES, SD - Equipment: Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 23; injuries: minor; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, waiver time limited special; last flight review March 10, 2014; seat: single; restraint: 5-point; flight hours: 1,875 total, 77 in this make and model, 1,833 as pilot in command, 319 in the last 90 days, 113 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 20° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °F, dew point 64 °F - Altimeter: 29.69 inHg - Observed at: KPIR, 13 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 20150904012839A](https://openairdocs.org/incident/20150904012839A), Sep 4, 2015: Air Tractor Inc AT-402A, Ft Pierre, SD, Substantial damage. On September 4, 2015 at approximately 0900 CST an Air tractor[privacy data omitted] hit a tower guy wire during spray operations. Clear conditions prevailed… ## Docket (3 files) The files NTSB released with the investigation on September 29, 2015, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=91942. 3.3 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40432227&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Photos (item 2, .PDF, 3 photos, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40432228&FileExtension=.PDF&FileName=Photos-Master.PDF - Maps or Charts of Accident Area (item 3, .PDF, 1 photo, 280 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40432229&FileExtension=.PDF&FileName=Maps%20or%20Charts%20of%20Accident%20Area-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.