Investigation Summary
The incident was rooted in the transition to the metric system in Canada. The Boeing 767 was Air Canada's first aircraft to use metric fuel measurements (kilograms), while the rest of the fleet used pounds. Due to a faulty Fuel Quantity Indicator System (FQIS), the ground crew and pilots performed manual calculations using a drip tube. They used a conversion factor of 1.77 (lb/L) instead of 0.8 (kg/L), leading them to believe they had 22,300 kg of fuel when they actually had only 22,300 lbs (roughly 10,115 kg). This was less than half the fuel required for the flight.
Final Conclusions
The primary cause was a human error in fuel calculation compounded by maintenance procedures that allowed the aircraft to fly with a known faulty fuel gauge system. The successful outcome was attributed to the exceptional gliding skills of Captain Robert Pearson and First Officer Maurice Quintal.
Video Analysis
The Gimli Glider: Air Canada Flight 143 — A detailed look at how a Boeing 767 ran out of fuel mid-flight and the incredible dead-stick landing that followed.
Watch on YouTube ↗If playback is blocked, the owner has disabled embedding — use the link above.
Systems & Failure Modes
FQIS
Fuel Quantity Indicator System; it was malfunctioning, necessitating manual fuel calculations.
RAT
Ram Air Turbine; a small propeller that deploys to provide emergency hydraulic pressure when engines fail.
Dripstick
A manual tool used to measure the fuel level in the tanks from beneath the wing.
Interesting Facts
- 01The aircraft was the first in Air Canada's fleet to use the metric system for fuel.
- 02The crew calculated they had 22,300 kg of fuel, but they actually had 22,300 lbs.
- 03The Boeing 767 has a glide ratio of approximately 12:1.
- 04The nose gear did not lock and collapsed upon landing, which actually helped stop the plane.
- 05There were no fatalities among the 61 passengers and 8 crew members.
Safety Actions & Advisories
Standardization of Units
Air Canada and other operators standardized training and procedures to prevent the mixing of metric and imperial units during fuel loading.
FQIS Maintenance Procedures
Revised maintenance protocols were established to ensure aircraft do not fly with critical fuel gauging systems disabled without redundant verification.