Air Canada Flight 143 was a Canadian scheduled domestic passenger flight between Montreal and Edmonton that ran out of fuel on July 23, 1983, at an altitude of 41,000 feet , midway through the flight. The flight crew successfully glided the Boeing 767 to an emergency landing at a former Royal Canadian Air Force base in Gimli, Manitoba that had been converted to a motor racing track. This unusual aviation incident earned the aircraft the nickname "Gimli Glider". The accident is commonly blamed on mistaking pounds for kilograms, which resulted in the aircraft carrying only 45% of its required fuel load. However, the units error was the last in a series of failures that aligned in a Swiss cheese model to cause the accident.
Here is our blog How a flight landed without fuel from 40k feet
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On July 22, 1983, Air Canada Boeing 767 C-GAUN, underwent routine checks in Edmonton. The technician found a defective Fuel Quantity Indication System, so he disabled the defective channel and made an entry in the logbook. The next morning, Captain John Weir and co-pilot Captain Donald Johnson were told about the problem. Since the FQIS was operating on a single channel, a dripstick reading was taken to obtain a second measurement of fuel quantity. Weir converted the dripstick reading from cm to litres to kilograms, finding that it agreed with the FQIS. The plane flew to Toronto and then Montreal without incident.
At Montreal, Captain and First Officer took over the airplane for Flight 143 to Ottawa and Edmonton. Officer told Captain that there was a problem with the FQIS, and Captain decided to take on enough fuel to fly to Edmonton without refueling in Ottawa, 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 self-test.
After taking a dripstick measurement, Captain converted the reading from centimetres to litres to kilograms. He did his calculation with the density of jet fuel in pounds/litre instead of kilograms/litre. He entered the reading into the flight management computer , which tracked the amount of fuel remaining in kilograms. The airplane flew to Ottawa without incident, where another dripstick measurement was taken and converted using the density in pounds/litre. Since the aircraft appeared to have enough fuel to reach Edmonton, no fuel was loaded at Ottawa.
While Flight 143 was cruising over Red Lake, Ontario at 41,000 feet .The aircraft's cockpit warning system sounded, indicating a fuel pressure problem on the aircraft's left side. Assuming that a fuel pump had failed, the pilots turned off the alarm, knowing that the engine could be gravity-fed in level flight. A few seconds later, the fuel pressure alarm also sounded for the right engine. This prompted the pilots to divert to Winnipeg.
Within seconds, the left engine failed and the pilots began preparing for a single-engine landing. As they communicated their intentions to controllers 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. Seconds later, the right-side engine also stopped and the 767 lost all power. Flying with all engines out was something that was never expected to occur, so it had never been covered in training.
The 767 was one of the first airliners which operated on the electricity generated by the aircraft's jet engines. With both engines stopped, the system went dead and most of the 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 controls the pilots were already descending through 35,000 feet when the second engine shut down. They immediately searched their emergency checklist for the section on flying the aircraft with both engines out, only to find that no such section existed. Captain Pearson was an experienced glider pilot, so he was familiar with flying techniques almost never used in commercial flight. To have the maximum range and therefore the largest choice of possible landing sites, he needed to fly the 767 at the optimum glide speed. Making his best guess as to this speed for the 767, he flew the aircraft at 220 knots (410 km/h). First Officer Maurice Quintal began to calculate whether they could reach Winnipeg. He used the altitude from one of the mechanical backup instruments, while the distance travelled was supplied by the air traffic controllers in Winnipeg, measured by the aircraft's radar echo observed at Winnipeg. In 10 nautical miles (19 km) the aircraft lost 5,000 feet
At this point, Quintal proposed landing at the former RCAF Station Gimli, a closed air force base where he had once served as a pilot for the Royal Canadian Air Force. Unbeknownst to Quintal or to 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 incident and the area around the decommissioned runway was full of cars and campers. Part of the decommissioned runway was being used to stage the race.
Without main power, the pilots used a gravity drop, which allows gravity to lower the landing gear and lock it into place. The main gear locked into position, but the nose wheel did not; this later turned out to be advantageous. As the aircraft slowed on approach to landing, the reduced power generated by the ram air turbine rendered the aircraft increasingly difficult to control.
As the plane drew near the runway, it became apparent that the aircraft was coming in too high and fast, raising the danger of the 767 running off the runway before it could be stopped. The lack of hydraulic pressure prevented flap/slat extension that would have, under normal landing conditions, reduced the stall speed of the aircraft and increased the lift coefficient of the wings to allow the airliner to be slowed for a safe landing. The pilots briefly considered a 360-degree turn to reduce speed and altitude, but they decided that they did not have enough altitude for the manoeuvre. Pearson decided to execute a sideslip to increase drag and lose altitude. This manoeuvre, performed by "crossing the controls" (applying rudder in one direction and ailerons in the other direction) is commonly used in gliders and light aircraft to descend more quickly without increasing forward speed, but it is practically never executed in large jet airliners outside of rare circumstances like those of this flight.
Complicating matters yet further was the fact that with both of its engines out, the plane made virtually no noise during its approach. People on the ground thus had no advance warning of the impromptu landing and little time to flee. As the gliding plane closed in on the decommissioned runway, the pilots noticed that there were two boys riding bicycles within 1,000 feet (300 m) of the projected point of impact. Captain Pearson would later remark that the boys were so close that he could see the looks of sheer terror on their faces as they realized that a large, passenger-laden aircraft was bearing down on them - the 767-200, the aircraft type in question, was only classed as a medium-size airliner however when empty still weighed roughly 80 tonnes without passengers.
Two factors helped disaster: the failure of the front landing gear to lock into position during the gravity drop, and the presence of a guardrail that had been installed along the centre of the repurposed runway to facilitate its use as a drag race track. As soon as the wheels touched down on the runway, Pearson braked hard, skidding and promptly blowing out two of the aircraft's tires. The unlocked nose wheel collapsed and was forced back into its well, causing the aircraft's nose to slam into, bounce off, and then scrape along the ground. This additional friction helped to slow the airplane and kept it from crashing into the crowds surrounding the runway. After the airliner had touched down, the nose began to scrape along the guardrail in the centre of the race track, creating additional frictional drag that contributed to the plane's deceleration; Pearson applied extra right brake, which caused the main landing gear to straddle the guardrail. Air Canada Flight 143 came to a final stop on the ground 17 minutes after running out of fuel.
There were no serious injuries among the 61 passengers or the people on the ground. . A minor fire in the nose area was extinguished by racers and course workers equipped with portable fire extinguishers.
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