[4][5] The aircraft ran out of fuel halfway to Edmonton, where maintenance staff were waiting to install a working FQIS that they had borrowed from another airline.

Since the FQIS was now operating on a single channel, a dripstick reading was taken to obtain a second fuel quantity measurement.

[6] At Montreal, Captain Robert "Bob" Pearson and First Officer Maurice Quintal took over the airplane for Flight 143 to Ottawa and Edmonton.

Assuming that a fuel pump had failed, the pilots turned off the alarm,[10] knowing that the engine could be gravity-fed in level flight.

The 767 was one of the first airliners to include an electronic flight instrument system, which operated on the electricity generated by the aircraft's jet engines.

With both engines stopped, the system went dead, and most screens went blank, leaving only a few basic battery-powered emergency flight instruments.

[10] Captain Pearson was an experienced glider pilot, so he was familiar with flying techniques rarely used in commercial flight.

Pearson needed to fly the 767 at the optimum glide speed to have the maximum range and, therefore, the largest choice of possible landing sites.

Unbeknownst to Quintal or the air traffic controller, a part of the facility had been converted to a race track complex, now known as Gimli Motorsports Park.

The failure of the nose wheel to lock would later prove to be a serendipitous advantage after touchdown for the safety of those on the converted runway.

The lack of hydraulic pressure prevented flap/slat extension that would have, under normal conditions, reduced the aircraft's stall speed and increased the lift coefficient of the wings, to slow the airliner for a safe landing.

As the gliding plane closed in on the decommissioned runway, the pilots noticed boys were riding bicycles within 1,000 feet (300 m) of the projected point of impact.

[15] Two factors helped avert disaster: the failure of the front landing gear to lock into position during the gravity drop, and a guardrail installed along the centre of the repurposed runway to facilitate its use as a drag race track.

It noted that Air Canada "neglected to assign clearly and specifically the responsibility for calculating the fuel load in an abnormal situation.

"[6]: 65  It further found that the airline had failed to reallocate the task of checking fuel load (which had been the responsibility of the flight engineer on older aircraft flown with a crew of three).

The safety board also said that Air Canada needed to keep more spare parts, including replacements for the defective fuel quantity indicator, in its maintenance inventory, and provide better, more thorough training on the metric system to its pilots and fuelling personnel.

In the event of one failing, the other could still operate alone, but in that case, the indicated quantity was required to be cross-checked against a floatstick measurement before departure.

However, before he could disable the second channel again, he was called away to perform a floatstick measurement of fuel remaining in the tanks, leaving the circuit breaker tagged (which masked the fact that it was no longer pulled).

Pearson consulted the master minimum equipment list (MMEL), which indicated that the aircraft was not legal to fly with blank fuel gauges.

C-GAUN was the 47th Boeing 767 off the production line and had been delivered to Air Canada fewer than four months prior to this flight.

To add to his misconceptions about the aircraft's flying condition since the previous day, reinforced by what he saw in the cockpit, Pearson now had a signed-off maintenance log, which had become customarily preferred over the MMEL.

The Boeing 767 belonged to a new generation of aircraft that flew with only a pilot and co-pilot, but Air Canada had not clearly assigned responsibility for supervising the fuelling.

The fueler at Edmonton knew the density of jet fuel in kg/L, and he calculated the correct number of litres to pump into the tanks.

[6]: 43–44 Following Air Canada's internal investigation, Captain Pearson was demoted for six months, and First Officer Quintal was suspended for two weeks for allowing the accident to happen.

[20] Following a successful appeal against their suspensions, Pearson and Quintal were assigned as crew members aboard another Air Canada flight.

[23] Pearson remained with Air Canada for ten years and then moved to flying for Asiana Airlines; he retired in 1995.

The Discovery Channel Canada / National Geographic TV series Mayday covered the accident in a 2008 episode titled "Gimli Glider".

[10][23] That summer, on July 23, 2008, the 25th anniversary of the accident, pilots Pearson and Quintal were celebrated in a parade in Gimli, and a mural was dedicated to commemorate the landing.

[26] In April 2013, the Gimli Glider was offered for sale at auction, by a company called Collectable Cars,[9] with an estimated price of CA$2.75–3 million.

Parts of the metal fuselage skin were made into 10,000 sequentially numbered luggage tags, and as of 2015[update], were offered for sale by a California company, MotoArt, under the product name "PLANETAGS".