Gimli Glider

Air Canada Flight 143 was a scheduled domestic passenger flight between Montreal and Edmonton. On July 23, 1983, it ran out of fuel midway through the flight.

The fuel gauge was not operating, and the plane's tanks had been underfilled because of an incorrect calculation.

The flight crew successfully glided the Boeing 767 from an altitude of to an emergency landing at a former Royal Canadian Air Force base in Gimli, Manitoba, which had been converted to a racetrack, Gimli Motorsports Park. The landing caused no serious injuries to passengers or persons on the ground, and only minor damage to the aircraft. The aircraft was repaired, and remained in service until its retirement in 2008. This unusual aviation accident earned the aircraft the nickname "Gimli Glider".

The accident was caused by a series of issues, including a failed fuel-quantity indicator sensor (FQIS) and confusion between pounds and kilograms. The fuel sensors in 767s had high failure rates, and the only replacement sensor available when the failure was detected was also nonfunctional. This problem was logged when it was discovered, but later, the maintenance crew misunderstood the problem and turned off the backup FQIS. This required the volume of fuel to be manually measured using a dripstick.

The navigational computer required a number to be entered specifying the amount of fuel on board, in kilograms; however, an incorrect conversion from volume to mass was applied, which led the pilots and ground crew to agree that there was enough fuel for the remaining trip when it was actually 45% of the required amount. 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.

At Montreal, Captain Bob Pearson and First Officer Maurice Quintal took over the airplane for Flight 143 to Ottawa and Edmonton. During the handover, Weir told Pearson that a problem existed with the FQIS, and Pearson decided to take on enough fuel to fly to Edmonton without refuelling in Ottawa. Meanwhile, an avionics technician had entered the cockpit and read the logbook. While waiting for the fuel truck, he enabled the defective channel and performed an FQIS self-test. Distracted by the arrival of the fuel truck, he left the channel enabled after the FQIS failed the test. Pearson entered the cockpit to find the FQIS blank, as he expected.

Running out of fuel

While Flight 143 was flying over Red Lake, Ontario, at shortly after 8 pm CDT, A few seconds later, the fuel pressure alarm also sounded for the right engine. This prompted the pilots to divert to Winnipeg.

The left engine failed within seconds, and the pilots began preparing for a single-engine landing. As they communicated their intentions to controllers in Winnipeg and tried to restart the left engine, the cockpit warning system sounded again with the "all engines out" sound, a sharp "bong" that no one in the cockpit could recall having heard before. Flying with all engines out was never expected to occur, so it had never been covered in training. Adding to both the crew's and the controllers' problems, the plane's transponder failed, stopping the altitude reporting function and forcing the controllers to revert to primary radar to track the plane.

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. While these provided sufficient information to land the aircraft, the backup instruments did not include a vertical speed indicator that could be used to determine how far the aircraft could glide.

On the Boeing 767, the control surfaces are so large that the pilots cannot move them with muscle power alone. Instead, hydraulic systems are used to multiply the forces applied by the pilots. Since the engines supply power for the hydraulic systems, in the case of a complete power outage, the aircraft was designed with a ram air turbine that swings out from a compartment located beneath the bottom of the 767 when the second engine shut down. They had searched their emergency checklist for the section on flying the aircraft with both engines out, only to find that no such section existed.

At this point, Quintal proposed landing at the former RCAF Station Gimli, a closed air force base where he had once served at a pilot training center for the Royal Canadian Air Force. 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. It included a road-race course, a go-kart track, and a dragstrip. A Canadian Automobile Sport Clubs-sanctioned sports-car race hosted by the Winnipeg Sports Car Club was underway at the time of the accident. The area around the decommissioned runway was full of cars and campers. Part of the decommissioned runway was being used to stage the race.

As the aircraft slowed on approach to landing, the reduced power generated by the ram air turbine rendered the aircraft increasingly difficult to control.

No serious injuries occurred among the 61 passengers or the people on the ground. As the aircraft's nose had collapsed onto the ground, its tail was elevated, so some minor injuries occurred when passengers exited the aircraft via the rear slides, which were not sufficiently long to accommodate the increased height. Racers and course workers with portable fire extinguishers extinguished a minor fire in the nose area.

Investigation

The Canadian Aviation Safety Board (predecessor of the modern Transportation Safety Board of Canada) reported that Air Canada management was responsible for "corporate and equipment deficiencies". Their report praised the flight and cabin crews for their "professionalism and skill". It noted that Air Canada "neglected to assign clearly and specifically the responsibility for calculating the fuel load in an abnormal situation". This reports that the fuel gauges were blank and that the second FQIS channel was disabled, but it does not make clear that the latter fixed the former.

The aircraft flew from Edmonton to Montreal on the day of the accident. Before departure, the engineer informed the pilot of the problem and confirmed that the tanks must be verified with a dripstick. In a misunderstanding, the pilot believed the aircraft had been flown with the fault from Toronto the previous afternoon. The flight to Montreal proceeded uneventfully, with fuel gauges operating correctly on the single channel.

On arrival in Montreal, a new crew boarded for the return flight to Edmonton. The outgoing pilot informed Captain Pearson and First Officer Quintal of the problem with the FQIS and passed along his mistaken belief that the aircraft had flown the previous day with this problem. In a further misunderstanding, Captain Pearson believed he was also being told that the FQIS had been completely unserviceable since then.

While the aircraft was being prepared to return to Edmonton, a maintenance worker decided to investigate the problem with the faulty FQIS. To test the system, he re-enabled the second channel, at which point the fuel gauges in the cockpit went blank. However, before he could disable the second channel again, he was called away to perform a dripstick measurement of fuel remaining in the tanks, leaving the circuit breaker tagged (which masked the fact that it was no longer pulled). The FQIS was now completely unserviceable, and the fuel gauges were blank.

On entering the cockpit, Captain Pearson saw what he was expecting to see—blank fuel gauges and a tagged circuit breaker. Pearson consulted the master minimum equipment list (MMEL), which indicated that the aircraft was not legal to fly with blank fuel gauges. Still, due to a misunderstanding, Pearson believed it was safe to fly if the amount of fuel was confirmed with measuring sticks.

The 767 was still a very new aircraft, having flown its maiden flight in September 1981. 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. In that time, 55 changes had been made to the MMEL, and some pages were blank pending development of procedures.

Because of this unreliability, maintenance personnel authorizing flights had become standard practice. 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.

Miscalculation during fuelling

In older aircraft with a three-person crew, the flight engineer kept a fuel log and supervised the fuelling. 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 flight management computer (FMC) measures fuel consumption, allowing the crew to keep track of fuel burned as the flight progresses. It is normally updated automatically by the FQIS, but the fuel quantity can also be entered manually. Because the FMC would reset during the stopover in Ottawa, the captain had the fuel tanks measured again with the dripstick. With of fuel in the tanks, the fueler gave a density of 1.78. Repeating the same error, Captain Pearson determined that he had of fuel and entered this number into the FMC. However, he actually had just of fuel. Following a successful appeal against their suspensions, Pearson and Quintal were assigned as crew members aboard another Air Canada flight. In 1985, Pearson and Quintal were awarded the first ever Fédération Aéronautique Internationale Diploma for Outstanding Airmanship. Several attempts by other crews who were given the same circumstances in a simulator at Vancouver resulted in crashes. Quintal was promoted to captain in 1989. Pearson remained with Air Canada for ten years and then moved to flying for Asiana Airlines; he retired in 1995.

The aircraft was temporarily repaired at Gimli and flew out two days later to be fully repaired at a maintenance base in Winnipeg. The aircraft was returned to service with Air Canada after the full repair.

The 1995 television movie Falling from the Sky: Flight 174 is loosely based on this event.

The Discovery Channel Canada / National Geographic TV series Mayday covered the accident in a 2008 episode titled "Gimli Glider". The episode featured interviews with survivors, including Pearson and Quintal, and a dramatic flight recreation.

Retirement

right|thumb|C-GAUN parked at [[Mojave Airport & Spaceport in February 2008 (C-GAUN's Air Canada livery was subsequently removed.)]]

After almost 25 years of service, C-GAUN flew its last revenue flight on January 1, 2008. The Gimli Glider then began its final voyage on January 24, 2008, as AC7067, from Montreal Trudeau to Tucson International Airport and final flight to retirement at California's Mojave Airport. The flight was captained by Jean-Marc Bélanger, a former head of the Air Canada Pilots Association; captains Pearson and Quintal were also on board, as were three of the six flight attendants from Flight 143.

In April 2013, the Gimli Glider was offered for sale at auction, by a company called Collectable Cars, However, bidding only reached and the lot was unsold.

According to a website dedicated to saving the aircraft, the Gimli Glider was scrapped in early 2014. Parts of the metal fuselage skin were made into 10,000 sequentially numbered luggage tags, and , were offered for sale by a California company, MotoArt, under the product name "PLANETAGS".

In June 2017, a permanent museum exhibit of the event opened in Gimli. The exhibit includes a cockpit mock-up flight simulator, and , sold event memorabilia.

On June 27, 2025, The Gimli Glider Exhibit museum displayed the recently recovered and transported cockpit of C-GAUN in a ceremony reuniting it with Captain Bob Pearson.

References

External links

The Gimli Glider Exhibit website
Damn Interesting: The Gimli Glider
CBC Digital Archives: 'Gimli Glider' lands without fuel
Photo of C-GAUN after the landing
Picture of C-GAUN in storage (airliners.net)