A Tiny Error Left An Air Canada Boeing 767 Flight With 2 Dead Engines. How The Pilot Landed It

No one wants to hear that the aircraft they are sitting in has lost power. It is the kind of sentence that belongs in the Mission Impossible franchise, not in real life. And yet, in aviation history, there are rare moments when the unthinkable happens.

One such moment unfolded on July 23, 1983, when Air Canada Flight 143 (a passenger flight between Montreal and Edmonton) lost all engine power at 41,000 feet due to a calculation error. What followed was not just an emergency, but an aviation story that continues to be studied decades later.

It would come to be known as the Gimli Glider.

What Happens When A Plane Becomes A Glider

To understand why this story is extraordinary, it helps to simplify one thing: planes are not supposed to fly without engines.

But technically, they can.

A glider is an aircraft designed to fly without engines. It stays in the air by using its wings to generate lift, slowly descending while moving forward. The trade-off is simple: to keep moving, it must lose altitude.

Think of it like this:

• Height is stored energy
• Speed is how that energy is used
• A glider "spends" height to stay airborne.

Now here's the catch. A massive commercial jet like the Boeing 767 is not built to glide efficiently. It is heavy, complex, and depends heavily on its engines.

Yet, on that day, it had no choice.

What Led To The Incident

The disaster did not begin in the sky. It began on the ground.

Flight 143 was operating with a faulty fuel quantity indication system. In simple terms, the cockpit had no reliable way of knowing how much fuel was actually in the tanks.

That should have grounded the aircraft. But a workaround was used. Fuel was measured manually using a dipstick, and calculations were done by hand.

This is where things unravelled.

Canada was transitioning from imperial to metric units at the time. The aircraft required fuel calculations in kilograms. But the crew used a conversion factor meant for pounds.

The numbers looked correct. They weren't.

Instead of carrying the required fuel, the aircraft had less than half of what it needed.

'We Believed We Had Enough Fuel'

The flight took off from Montreal and later stopped in Ottawa. Even there, the same calculation mistake was repeated.

Everything appeared normal.

At cruising altitude, First Officer Maurice Quintal made a routine announcement. Minutes later, warning alarms began.

Captain Robert Pearson later explained, "We believed we had a failed fuel pump in the left wing."

Then the second warning came.

Then the first engine failed.

Then the second.

Quintal recalled the moment vividly, "It's a sound that Bob and I had never heard before. It's not in the simulator."

What Happened Next

To understand what happens next, picture this: Modern aircraft rely on engines not just for thrust, but also for power.

When both engines failed:

• Cockpit screens went blank
• Hydraulics weakened
• Navigation systems shut down

Pearson described it starkly in an interview later, "The cockpit became the blackest place in the world."

The only thing keeping the aircraft controllable was a last-resort device called a ram air turbine. It is essentially a small propeller that pops out into the airflow and generates minimal power.

Just enough to steer.

Flying A Jet Like A Glider

At this point, Pearson did something unusual: he relied on his experience as a glider pilot.

He needed to maintain the perfect glide speed to travel the farthest distance possible. Too fast, and the aircraft would descend quickly. Too slow, and it would stall.

He settled on about 220 knots.

With no vertical speed indicator, limited instruments, and no engines, he steered visually.

"I steered by the clouds beneath us," he said.

A Runway That Wasn't A Runway

The pilots initially aimed for Winnipeg Airport. But they soon realised they would not make it.

Quintal suggested an alternative: a former air force base in Gimli, Manitoba, where he had once trained.

What they did not know was this: The runway had been repurposed.

Part of it was now a racetrack, filled with cars, tents, and spectators. As they approached, another problem emerged. The aircraft was too high and too fast.

Pearson made a bold decision. He performed a manoeuvre called a forward slip, typically used in small aircraft.

In simple terms:

• The plane tilts sideways
• Air resistance increases
• The aircraft loses altitude faster

This manoeuvre had rarely, if ever, been used on a jet of that size.

Landing Into The Unexpected

The approach was eerily silent. With no engines, people on the ground heard nothing.

At the last moment, the pilots saw people and vehicles on the runway.

The runway had been repurposed into a running track. Photo: X

Pearson landed hard. Tyres burst. The nose gear collapsed. The aircraft skidded to a stop just 100 feet from spectators.

A small fire broke out, but was quickly extinguished. And no one was seriously injured (Occupants 69; Passengers: 61 and 8 crew members)

What Went Wrong And What Changed

The investigation did not treat this as a miracle alone. It was also a failure of systems.

The findings pointed to:

• Confusion between metric and imperial units
• Poor communication among the crew and maintenance
• Incomplete procedures for new aircraft
• Lack of training for manual fuel calculations

As one report concluded, responsibility lay not just with individuals but with the system itself.

Yet, the same report praised the crew's composure and skill. And despite initial disciplinary action, both pilots were later recognised for their extraordinary airmanship.

In 1985, they were awarded honours for their actions.

The aircraft itself was repaired and continued flying for nearly 25 more years before being retired in 2008.