Today in 1983, Air Canada Flight 143, on its way from Montreal to Edmonton via Ottawa, ran out of fuel and lost both engine thrust and electrical power at 41,000 feet. The crew's amazing actions in the following minutes saved the lives of the plane’s passengers. The causes of the incident ensured that the story of the Gimli Glider will serve as a cautionary tale in aviation circles for generations to come.
Air Canada Flight 143 was a Boeing 767, an aircraft model that had only been in service for two years at that time. The particular plane in question had not yet been in service for four months by July, 1983. It was the first large aircraft flown by Air Canada that only required a pilot and co-pilot and eliminated the position of flight engineer, the person who would normally have been responsible for calculating the fuel load necessary for a given flight. This omission would become important during the post-incident investigation.
Earlier on the day of the incident, the aircraft had been flown from Edmonton to Montreal. A pre-flight inspection by a maintenance engineer showed that the plane’s Fuel Quantity Indicator System (FQIS) was malfunctioning. The FQIS had a built-in redundancy in which the plane’s remaining fuel was measured by two separate sensors and the results were compared to ensure accuracy. The pilot and co-pilot were shown only one amount however, assuming the two measurements agreed. The engineer in Edmonton noticed that the FQIS quit working entirely unless he pulled the fuse for one of the measuring sensors. He informed the pilot of this and the flight was made with the FQIS working with only one measurement sensor.
Once in Montreal, another Air Canada engineer looked at the FQIS and reconnected the second measuring sensor, which caused the system to stop working again entirely. The engineer was then called away to check another system and left the FQIS in non-working order. The new flight’s captain, Robert Pearson, and First Officer Maurice Quintal were told about the FQIS problem by the pilot who had flown the plane from Edmonton to Montreal earlier in the day. However, they were under the mistaken belief that the FQIS was not working at all on the earlier flight, so were not alarmed when the gauge was blank as they entered the cockpit. Instead of grounding the flight, the crew decided to measure the fuel via dripstick and track fuel consumption via the Flight Management Computer.
It was during this time that a critical error was made. In 1983, Canada was in the middle of a nation-wide conversion from Imperial units to the metric system. The 767s being put into service with Air Canada were the first to use the metric system; every other aircraft model in the fleet still used Imperial measurements. In the process of converting liters to kilograms to pounds to gallons, a wrong conversion factor was used and the aircraft ended up with less than half the necessary fuel on board for the trip. After the plane finished the first leg of the trip by landing in Ottawa, Captain Pearson had the fuel measured again via dripstick. He again made a conversion error and the aircraft took off with the 69 passengers and crew onboard, heading towards Edmonton with no chance of reaching there.
Air Canada Flight 143 was over Red Lake, Ontario when an alarmed sounded, notifying the crew that there was a fuel pressure problem on the plane’s left side. The pilots turned off the port side fuel pump, assuming it had failed. This was not a serious problem as gravity could still feed fuel to the aircraft’s engines. The alarm sounded again a few seconds later, this time accompanied by the failure of the left engine. Captain Pearson decided to divert to Winnipeg and land using the 767’s one running engine. As they talked to air traffic controllers, yet another alarm told the pilots that both engines had now failed. Most of the cockpit instrumentation went dark, leaving only a few battery-powered basic instruments. The plane’s ram air turbine, a small generator powered by the forward motion of the aircraft, quickly deployed and maintained power to the hydraulic system, which meant that the pilots could at least somewhat control the plane. Air Canada Flight 143, over six miles above the earth, was now a giant glider.
Fortunately for everyone present on the Air Canada flight that day, Captain Pearson was an experienced glider pilot. Up to that point in its short flight history, no one had made an unpowered landing in a Boeing 767. In fact, the aircraft’s emergency checklist had no section for such a contingency. Captain Pearson guessed that the best glide ratio speed for a 767 was 220 knots, or 250 miles per hour. Using the plane’s altimeter and information from air traffic controllers, the pilots determined that they were maintaining a glide ratio of 12:1; that is, 12 miles of forward travel for every one mile of descent. They were not going to make it to Winnipeg.
First Officer Maurice Quintal, who had once served as a Royal Canadian Air Force pilot, remembered the Air Force Station at Gimli, Manitoba. It had been closed since 1971, but it still boasted two parallel runways nearly 7,000 feet long. If they could make it there, their chances of making a safe landing would improve dramatically. They would have to glide for 17 harrowing minutes over dense forest, maintaining a constant rate of descent the entire way.
As the airliner approached the old air force base, the pilots were faced with three problems: first, they were too high and going too fast to make a head-on approach landing as they had planned. They considered trying to fly a 360 degree turn in order to lose speed and altitude, but Captain Pearson was afraid they would not have enough momentum left for a safe landing. He decided to execute a forward slip, a maneuver in which an aircraft stays on track while slipping sideways. This causes an immediate loss of speed and increases the rate of descent.
This introduced the second problem. As the plane slowed, the ram air turbine began slow down, which meant the hydraulic system began to lose pressure. This made the aircraft more difficult to control and made use of the wing flaps impossible. This meant the plane would still land at a higher than normal speed.
The third and most harrowing problem presented itself as the plane lined up with one of the runways. What neither Pearson or Quintal knew was that while one of the runways of the old Air Force base could still be used, the other one had been converted into a drag strip complete with a guardrail running down the centerline. A Winnipeg auto club was, coincidentally, hosting a family day at the converted airfield that day, so the apron of the non-converted runway was being used as a parking space and was full of cars, trucks and trailers. The drag strip would have to do.
The pilots tried to lower the 767s landing gear using gravity, but the nose wheel failed to lock into position. As the plane made contact with the runway, Captain Pearson pushed the brakes as hard as he could, which caused two of the plane's landing gear tires to blow. The nose wheel collapsed and folded back up into its well, leaving nothing to hold the front of the aircraft up. The underside of the nose scraped along the runway until it came into contact with the guard rail, which raised the front of the plane a little and helped to slow it down more rapily.
As the Air Canada craft came to a halt, a small fire began in the nose area. People working at the drag strip, already standing by with fire extinguishers in case one of the cars caught on fire, quickly put out the blaze. None of the passengers and crew were hurt by the landing itself. Several passengers were injured while sliding down the rear emergency chutes, which were at too steep an angle due to the higher than normal height of the rear tail section. These injuries were treated by a doctor who happened to be on-scene at the time of the landing.
Investigators eventually found both the mechanics and pilots at fault in the Gimli glider incident. However, the pilots and crew were praised for handling the situation with professionalism and skill. Captain Pearson was demoted for six months and First Officer Quintal was suspended for two weeks. Quintal was promoted to Captain six years later and Pearson returned to his captaincy until his retirement in 1993. The Boeing 767, thereafter known as the Gimli Glider, remained in service with Air Canada for the next 25 years. In January, 2008, it was flown to the Mojave Airport and is slowly being dismantled for parts. On board for that final flight was the entire flight crew from that day in July, 1983.