1983
The Miracle of the Gimli Glider
A well-known part of recent Manitoba history is the flight (and descent) of the Gimli Glider, a tale of breath-taking incompetence, serial disasters and unearthly flying skills. The story is best told in the Wikipedia entry, which is reproduced here.
On July 22, 1983, Air Canada’s Boeing 767 (registration C-GAUN) flew from Toronto to Edmonton where it underwent routine checks. The next day, it was flown to Montreal. Following a crew change, it departed Montreal as Flight 143 for the return trip to Edmonton (with a stopover in Ottawa), with Captain Robert (Bob) Pearson, 48, and First Officer Maurice Quintal at the controls. Captain Pearson was a highly experienced pilot, having accumulated more than 15,000 flight hours. First Officer Quintal was also very experienced, having logged over 7,000 hours of total flight time.
On July 23, 1983, Flight 143 was cruising at 12,500 metres (41,000 ft) over Red Lake, Ontario. The aircraft’s cockpit warning system sounded, indicating a fuel pressure problem on the aircraft’s left side. Assuming a fuel pump had failed the pilots turned it off, since gravity should feed fuel to the aircraft’s two engines. The aircraft’s fuel gauges were inoperative because of an electronic fault indicated on the instrument panel and airplane logs.
During the flight, the management computer indicated that there was still sufficient fuel for the flight but only because the initial fuel load had been incorrectly entered; the fuel had been calculated in pounds instead of kilograms by the ground crew and the erroneous calculation had been approved by the flight crew. Effectively, this error meant that less than half the amount of intended fuel had been loaded. Because the incorrect fuel weight data had been entered into the system, it was providing incorrect readings. A few moments later, a second fuel pressure alarm sounded for the right engine, prompting the pilots to divert to Winnipeg. Within seconds, the left engine failed and they 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 long “bong” that no one in the cockpit could recall having heard before and was not covered in flight simulator training. Flying with all engines out was something that was never expected to occur and had therefore not been covered in training. Seconds later, with the right-side engine also stopped, the 767 lost all power, and most of the instrument panels in the cockpit went blank.
The 767 was one of the first airliners to include an electronic flight instrumentation system, which operated on the electricity generated by the aircraft’s jet engines. With both engines stopped, the system went dead, leaving only a few basic battery-powered emergency flight instruments. While these provided sufficient information with which to land the aircraft, a vertical speed indicator – that would indicate the rate at which the aircraft was descending and therefore how long it could glide unpowered – was not among them.
On airliners the size of the 767, the engines also supply power for the hydraulic systems without which the aircraft cannot be controlled. Such aircraft are therefore required to accommodate this kind of power failure. With the 767, this is usually achieved through the automated deployment of a hydraulic pump (and on some airplanes a generator) driven by a small turbine, which is driven by a propeller that rotates because of the forward motion of the aircraft in the manner of a windmill. As the Gimli pilots were to experience on their landing approach, a decrease in this forward speed means a decrease in the power available to control the aircraft.
In line with their planned diversion to Winnipeg, the pilots were already descending through 35,000 feet (11,000 m) 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 optimal glide speed. Making his best guess as to this speed for the 767, he flew the aircraft at 220 knots (410 km/h; 250 mph). 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, measuring the distance the aircraft’s echo moved on their radar screens. In 10 nautical miles (19 km; 12 mi) the aircraft lost 5,000 feet (1,500 m), giving a glide ratio of approximately 12:1.
At this point, Quintal proposed landing at the former RCAF Station Gimli, a closed air force base where he had once served as a Royal Canadian Air Force pilot. 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 the Saturday 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 power, the pilots used a gravity drop, which causes 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 ram air turbine generated less power, rendering the aircraft increasingly difficult to control.
As the runway drew near, it became apparent that the aircraft was coming in too high and fast, raising the danger of 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 aircraft to be slowed for a safe landing. The pilots briefly considered a 360-degree turn to reduce speed and altitude, but decided that they did not have enough altitude for the manoeuvre. Pearson decided to execute a forward slip to increase drag and lose altitude. This manoeuvre is commonly used with gliders and light aircraft to descend more quickly without increasing forward speed.
Complicating matters was the fact that with all of its engines out, the plane made virtually no noise during its approach. People on the ground thus had no warning of the impromptu landing and little time to flee. As the gliding plane closed in on the 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 commercial airliner was bearing down on them.
Two factors helped avert a potential 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 decommissioned runway to facilitate its use as a racetrack. As soon as the wheels touched down on the runway, Pearson braked hard, 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 careening into the crowds surrounding the runway. After the aircraft had touched down, the nose began to scrape along the guardrail in the centre of the tarmac; Pearson applied extra right brake, which caused the main landing gear to straddle the guardrail creating additional drag that further reduced the speed. 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 armed with fire extinguishers. Because the aircraft’s nose had collapsed onto the ground, its tail was elevated and there were some minor injuries when passengers exited the aircraft via the rear slides, which were not long enough to sufficiently accommodate the increased height.