Investigation Summary
Tanker 448 was operating in tandem with a Rockwell Turbo Commander 'bird dog' aircraft. The mission required a modified triangular circuit due to the steep terrain of the Fraser River canyon. The crew was instructed to maintain 3,100 feet ASL until crossing the edge of a ravine, providing approximately 100 to 150 feet of tree clearance, before descending 900 feet for the drop. During the first bombing run, the aircraft approached the ravine in a nose-high attitude. Approximately three seconds before impact, the bird dog crew observed the tanker descend unexpectedly. The aircraft struck treetops, coincident with an unanticipated retardant drop, and immediately entered a steep nose-down left-hand spin. The TSB conducted a flight test weeks later and confirmed that at the specific altitude and location of the crash, the terrain creates a visual illusion where the ground appears 400 to 500 feet below the aircraft when it is actually only 150 feet below. This unrecognized spatial disorientation likely led the captain to fly a profile that lacked sufficient clearance and energy to clear the rising ridge.
Final Conclusions
The Transportation Safety Board of Canada (TSB) concluded in report A10P0244 that visual illusion precluded an accurate assessment of the flight path, leading to a collision with trees on rising terrain. The illusion likely contributed to a low-energy condition that impaired performance when the crew initiated overshoot action. Following the tree strikes, the aircraft entered an aerodynamic stall and spin at an altitude too low for recovery. The investigation also noted that flight operations outside the approved weight and balance envelope increase the risk of unanticipated aircraft behavior. Furthermore, the lack of a cockpit voice recorder (CVR) and flight data recorder (FDR), which were not required by regulation for this aircraft type, hindered the ability to identify specific crew coordination factors.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Tim Whiting, 58. 3,500 hours fire suppression experience.
First Officer
Brian Tilley, 36. 26 hours fire suppression experience; undergoing line indoctrination.
Systems & Failure Modes
Retardant Delivery System
A hydraulic system with eight tank compartments. The emergency drop (E-drop) switch was located on the center pedestal but was guarded and required significant pilot attention to operate.
Angle of Attack (AOA) Indicator
A supplemental instrument intended to be a primary reference during low-level maneuvering; it provided visual data but no aural stall warning.
Emergency Locator Transmitter (ELT)
The ELT signal was not received following the crash, and the unit was not recovered from the wreckage.
Interesting Facts
- 01The aircraft was not equipped with a Cockpit Voice Recorder (CVR), Flight Data Recorder (FDR), or a stall warning device.
- 02The Captain had 17,000 total hours, while the First Officer was undergoing line indoctrination with only 26 hours of fire suppression experience.
- 03Post-impact examination of the engines and propellers indicated they were producing significant power at the time of impact.
- 04A TSB investigation flight confirmed a height-depth perception illusion at the accident site under similar conditions.
- 05The aircraft was equipped with an Angle of Attack (AOA) indicator, but it was positioned such that it was not fully visible from the right-hand seat.
Safety Actions & Advisories
E-Drop System Testing
The TSB identified a risk where the emergency drop system might not be functionally tested due to environmental concerns regarding retardant spillage on airport aprons.
Recorder Requirements
The investigation highlighted that the lack of CVR/FDR data precluded the identification of safety deficiencies, supporting ongoing calls for flight recorders in smaller commercial aircraft.