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ASN Wikibase Occurrence # 67974
Last updated: 7 April 2021
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Date:20-AUG-2009
Time:15:43
Type:Silhouette image of generic AT8T model; specific model in this crash may look slightly different
Air Tractor AT-802A
Owner/operator:Bureau of Land Managment/DOI
Registration: N807MA
C/n / msn: 802A-0145
Fatalities:Fatalities: 1 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Clan Alpine Mountains of Churchill County, Nevada, USA -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Fire fighting
Departure airport:Battle Mountain, NV (BAM)
Destination airport:Battle Mountain, NV (BAM)
Investigating agency: NTSB
Narrative:
The pilot was dropping fire retardant onto a saddle area located between the intersection of two perpendicular ridge lines. One of several witnesses reported that the airplane circled the area and then began a steep descent towards the intended drop point. The pilot did not release the load of retardant over the drop area. The witness observed the nose of the airplane pitch up and “mush through the flare.” The underside of the airplane then made contact with rising terrain within the saddle and continued uphill on its main landing gear toward a crest where the terrain dropped away. It then descended and collided with terrain in the valley below. Postaccident examination did not reveal any anomalies with the airplane, engine, or retardant dispersal system that would have prevented operation. The dispersal system’s operating procedures recommend that it be turned off during flight to prevent inadvertent dumping of the load. According to other pilots it is not uncommon to forget to re-engage the system prior to the drop. The dispersal system included an emergency manual release mechanism that could be used in the event of a primary system failure or an inadvertent oversight by the pilot to turn the system on; however, impact damage prevented an accurate determination of the system's armed status prior to impact. Global Positioning System (GPS) information revealed an excessive rate of descent just prior to the expected drop, which corroborated witness accounts. Analysis of the accident location, with respect to the GPS data, density altitude, airplane load, and witness statements, would indicate that the airplane probably encountered a stall/mush at the drop area. The high density altitude and the airplane's flap settings would have diminished the climb performance considerably in its retardant loaded state. The airplane's continued trajectory after initial impact, as well as propeller witness marks and internal engine damage, indicated that the engine was producing power at the time of the accident.
Probable Cause: The pilot’s failure to maintain a stabilized approach prior to the retardant drop and his subsequent failure to release the retardant load, resulting in a stall/mush and collision with terrain.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20090820X10204&key=1


Images:


Photo: NTSB

Revision history:

Date/timeContributorUpdates
21-Aug-2009 07:33 Arrdee Added
21-Aug-2009 09:26 slowkid Updated
06-Jun-2010 07:32 harro Updated [Time, Aircraft type, Other fatalities, Departure airport, Destination airport, Source, Narrative]
21-Dec-2016 19:25 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
02-Dec-2017 16:00 ASN Update Bot Updated [Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative]

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