Pilot Debrief

AIR TRACTOR AT-802A near Austin, NV — 2009-08-20

Final reportWPR09GA407
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Date
2009-08-20
Location
Austin, NV, USA
Airport
BAM
Aircraft
AIR TRACTOR AT-802A
Registration
N807MA
Category
Airplane
Highest injury
Fatal
Fatalities
1
Phase of flight
Approach

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.

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.

Analysis

Primary failure mode
Controlled flight into terrain
First missed decision gate
Pilot could have opted for a different drop strategy or altitude.

NTSB coding

Evidence available

  • FDR / data
  • Photos
  • 34 docket documents
View NTSB final reportView NTSB docket

Docket documents34

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