- Seven Deadly Stupidities
- Posts
- How does a plane run out of fuel in mid-flight?
How does a plane run out of fuel in mid-flight?
Why we must always measure twice
George Pillari
October 31, 2024
Programming note: You can listen to this and future posts by clicking the “Listen Online” link at the top of the page.
At some point, everything fails.
On July 23, 1983, Air Canada Flight 143, a Boeing 767, was scheduled to fly from Montreal to Edmonton. The crew was responsible for calculating how much fuel the plane needed for the flight, a routine task in any flight operation. However, a seemingly minor detail was overlooked: the measurement units used to calculate fuel quantity were incorrect.
Canada had recently switched from the imperial system (eg, pounds and inches) to the metric system (eg, kilograms and centimeters), and as a result, the critical calculation of fuel needed for the trip was erroneously performed using pounds instead of kilograms.
This error meant that the plane was loaded with significantly less fuel than required for the flight. One pound is less than ½ kilogram. So, if the plane was loaded with 1000 pounds of fuel, it would have had less then ½ the amount of fuel needed for the journey. Ouch.
Image by author
This mistake went unnoticed during pre-flight checks, as both the ground crew and pilots failed to double-check the calculations or recognize the incorrect units being used.
As a result, the plane took off with far less fuel than needed to complete the flight. Midway through the trip, the cockpit’s fuel indicators alerted the pilots to the dangerously low fuel levels. Soon, both engines shut down due to fuel exhaustion, and the plane lost all power.
In an extraordinary display of skill, the pilots managed to glide the aircraft to a decommissioned airstrip in Gimli, Canada. The plane landed safely, with no loss of life or major injuries, earning it the nickname “The Gimli Glider.”
The Gimli Glider safely on the ground
A Human Failure
The aviation industry is known for its stringent safety protocols. Pilots and ground crews undergo extensive training and follow a checklist for nearly every task to minimize human error. Even in such a rigorously controlled environment, a simple unit conversion error nearly resulted in disaster. This illustrates how easy it is for humans to make errors, and why double-checking measurements should always be a priority.
The act of "measuring twice" isn't just about literal measurements — it's about verifying and re-verifying assumptions, data, and decisions.
Key Takeaways
Ultimately, the danger of not measuring twice lies in the potential for avoidable mistakes.
Slow down when in a complex situation and look for the points of failure.
Whether the task is routine or complex, taking the extra time to double-check ensures accuracy, prevents costly errors, and, as in the case of Flight 143, can even save lives.
Neglecting to Measuring Twice is one of the Seven Deadly Stupidities.
Reply