Investigation Summary
The flight was a ferry operation to support the Italian polar research program. The aircraft was heavily modified with internal long-range ferry tanks, increasing its maximum take-off weight to 17,500 pounds. During the cruise at 12,500 feet, the crew performed a left turn toward Terra Nova Bay that led them directly toward the Queen Alexandra Range. Investigators determined that while the aircraft was equipped with a Terrain Awareness and Warning System (TAWS), the specific Sandel ST3400 unit's database did not contain data for latitudes south of 70°S, rendering its forward-looking terrain avoidance (FLTA) mode inoperative in Antarctica. However, a secondary Garmin GNS 430W unit did have a valid worldwide database and likely provided a visual terrain advisory. SkyTrac data showed a climb was initiated in the final minute of flight, but the Twin Otter, operating at high weight and high density altitude, could not out-climb the terrain. The investigation was further hampered by the discovery that the Cockpit Voice Recorder (CVR) had failed weeks prior to the accident, leaving no record of crew coordination or the specific reasons for the early turn.
Final Conclusions
The Transportation Safety Board of Canada (TSB) concluded in report A13F0011, released on June 20, 2014, that the accident was a controlled flight into terrain (CFIT). The primary cause was the crew's decision to turn toward the destination before reaching the open region of the Ross Shelf, which brought the aircraft into conflict with Mount Elizabeth. Contributing factors included probable cloud obscuration of the mountain and the limitations of the aircraft's climb performance at high altitude and weight. The lack of a functional CVR and the absence of Antarctic data in the primary TAWS unit were also noted as significant safety deficiencies.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Robert (Bob) Heath, age 55. Eighth season in Antarctica.
First Officer
Michael (Mike) Denton, age 25. First season in Antarctica.
Systems & Failure Modes
Sandel ST3400 TAWS
A terrain awareness and warning system that was ineffective during the flight because its electronic database lacked coverage for the Antarctic region.
Garmin GNS 430W
A navigation receiver capable of visual terrain warnings; it contained a worldwide database and likely provided the advisory that prompted the crew's final climb attempt.
Fairchild L3 A100 CVR
The cockpit voice recorder which was found to be unserviceable, preventing investigators from reviewing crew communications.
SkyTrac ISAT-100
A position and data communicator capable of recording flight data in 5-second intervals, which allowed investigators to reconstruct the flight path.
Interesting Facts
- 01The aircraft was manufactured in 1979 and had accumulated over 28,200 flight hours.
- 02The final SkyTrac GPS position was recorded at 83°53'30"S, 168°33'45"E at 08:01 UTC.
- 03The crash site was located at an elevation of approximately 13,000 feet (3,960 meters) on a steep slope.
- 04The Cockpit Voice Recorder (CVR) recovered from the site contained no data from the accident flight; its last recording was from December 1, 2012.
- 05The primary TAWS unit (Sandel ST3400) displayed 'Terrain Fail' because its database did not cover regions south of 70°S.
- 06The aircraft was operating under a ferry permit at a weight of approximately 14,600 pounds.
- 07Search and rescue teams were unable to recover the bodies of the crew due to avalanche risks and extreme weather.
Safety Actions & Advisories
CVR Functionality Checks
Kenn Borek Air amended its pre-start checklist to include a functional check of the cockpit voice recorder.
Antarctic Navigation Improvements
The operator improved the accuracy of Antarctic navigational charts and developed specific VFR routes for long-distance flights.
TAWS Awareness Program
Implemented a training program to ensure crews are aware of TAWS database limitations when operating above 70°N or below 70°S.
Location
APPROXIMATE POSITION · AIRPORT LEVEL · Coordinates are the estimate published in the entered by an editor. The ring shows the accuracy the record supports, not the point of impact.