Aviation safety investigations & reports

Collision with terrain involving Air Tractor AT-401B, VH-DDW, near Dimbulah ALA, Qld, on 21 January 2017

Investigation number:
Status: Completed
Investigation completed

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On 21 January 2017, at about 0710 Eastern Standard Time, the pilot of an Air Tractor AT 401B aircraft, registered VH-DDW, was conducting aerial spraying operations at a property about 10 km NW of Mareeba Airport, Queensland. The pilot was the only person on board the aircraft.

Part way through spraying the load of chemical on an avocado plantation, the pilot climbed the aircraft at the end of a spray run, to about 200 ft above ground level. As the aircraft climbed, the engine suddenly made loud banging noises and the pilot estimated that the engine power reduced by about half.

The pilot levelled the aircraft and checked the fuel mixture and throttle controls but the engine did not respond. The power available continued to decrease as the pilot looked ahead for a suitable field to conduct a forced landing. The pilot selected a cleared area, but as the aircraft lost height, they realised that the aircraft was not going to make it to that field.

The pilot then radioed their loader driver and advised that they had engine trouble and asked them to contact emergency services. The loader driver had heard the abnormal noise the aircraft’s engine was making, and responded immediately to the pilot.

As the aircraft descended, the pilot sighted powerlines ahead and assessed that the aircraft would probably not make it over them. Therefore, the pilot descended to pass under the powerlines. The aircraft then collided with several lychee trees and a vehicle that was parked in an orchard. The aircraft came to rest upright and was substantially damaged. The pilot sustained a minor injury.

The accident highlights the importance of taking positive action and maintaining aircraft control when conducting a forced landing, while being aware of flare energy and aircraft stall speeds.

Aviation Short Investigations Bulletin - Issue 59

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General details
Date: 21 January 2017   Investigation status: Completed  
Time: 7:10 EST   Investigation level: Short - click for an explanation of investigation levels  
Location   (show map): Dimbulah (ALA), E 6 km    
State: Queensland   Occurrence type: Engine failure or malfunction  
Release date: 27 April 2017   Occurrence category: Accident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Air Tractor Inc  
Aircraft model AT-401B  
Aircraft registration VH-DDW  
Serial number 401B-0991  
Type of operation Aerial Work  
Sector Piston  
Damage to aircraft Substantial  
Departure point Mareeba, Qld  
Destination Dimbulah, Qld  
Last update 14 November 2018