It has been more than 39 years since this unbelievable incident occurred.
Nearly four decades ago, a series of technical malfunctions and human errors put an Air Canada Boeing 767 in a perilous situation. The aircraft ran out of fuel at an altitude of 41,000 feet. Yet, through the pilot’s resourcefulness and expert gliding skills, the plane managed to land safely at a former airfield, now repurposed as a race track. The miracle was that no serious injuries were sustained by the passengers or crew. The aircraft even continued to serve the airline for another 25 years.
Double alarms at 41,000 feet
On July 23rd, 1983, Air Canada Flight 143 departed from Montreal, Quebec, en route to Edmonton, Alberta via Ottawa. The trip was operated by a brand-new Boeing 767-200 aircraft, with registration code C-GAUN. This Canadian domestic flight carried 61 passengers and eight crew members.
Shortly after 8:00 pm, while cruising at an altitude of 41,000 feet over Red Lake, Ontario, the crew received a low fuel pressure warning for the left fuel pump. Believing it to be a failure, the pilots switched off the alarm.
Within moments, however, the right fuel pump alarm also sounded. Concerned by both warnings, the crew decided to change their course and head towards Winnipeg, which was approximately 120 miles away.
During the descent, the left engine unexpectedly failed. To compound the situation, there was a loud bang followed by an alarming cockpit announcement of “all engines out.” The aircraft had lost all power.
Instruments gone
Adding to the challenge of flying without engines was the fact that the Boeing 767 was equipped with an electronic instrument system powered by the engines themselves. Unfortunately, when the engines shut down, all the instruments went dark.
Thankfully, the plane was equipped with a ram air turbine (RAT) that provided emergency power to crucial instruments needed for landing. It also offered hydraulic support, making it possible for the crew to maneuver the aircraft. Without the RAT, physical strength alone would have been insufficient.
However, the emergency power supply did not include a vertical speed indicator. This indicator would have been useful for estimating the aircraft’s gliding capabilities. Interestingly, Gimli, an old Air Force Base, happened to be closer to the aircraft’s location than Winnipeg.
Experienced glider pilot in the cockpit
Leading the crew was Captain Robin ‘Bob’ Pearson, an experienced pilot with 15,000 hours of flying time. Accompanying him in the cockpit was First Officer Maurice Quintal, with 7,000 hours of flying experience. Fortunately, Captain Pearson was not only an accomplished pilot but also an experienced glider pilot. Meanwhile, First Officer Quintal had undergone training at Gimli during his military service.
Crabbed their way to the runway
Despite the absence of emergency services, the crew decided to attempt a landing at Gimli. However, they were unaware that the base had been repurposed as a race track, with an event scheduled on that day.
The heavy landing gears deployed automatically under the force of gravity. Unfortunately, the lighter nose gear only partially extended. Moreover, the aircraft was approaching the improvised ‘runway’ too quickly and from too high an altitude. To lose height and speed, the crew executed a side-slip maneuver. The Canadian Board of Inquiry report described this maneuver as follows:
“Captain Pearson and First Officer Quintal discussed the possibility of executing a side-slip to lose height and speed in order to land close to the beginning of the runway. Captain Pearson performed the side-slip on the final approach and touched down within 800 feet of the threshold.”
Upon touchdown, the nose gear buckled immediately. Remarkably, all 61 passengers survived the landing, with the exception of a few minor injuries sustained during the evacuation. Investigators discovered that only 64 liters of fuel remained in the tanks, and no leaks were found.
So how could this have happened?
The cause of the Gimli Glider incident can be attributed to a combination of technical issues, organizational challenges, human error, and the confusion caused by the metric system. The aircraft’s Fuel Quantity Indication System (FQIS) played a significant role in the chain of events.
The Boeing 767-200 was equipped with a dual processing channel, designed to function independently in case of failure. However, cross-checking the fuel quantity required a manual measurement using a floatstick. Following a similar incident a month earlier, an engineer in Edmonton ran a service check on C-GAUN’s FQIS. Unfortunately, the engineer disabled the second channel when the system failed, and tagged the circuit breaker. This temporarily resolved the issue and allowed the engineer to conduct a floatstick measurement. However, there was a miscommunication regarding the usage of the floatstick measurement, which led to confusion during the crew change in Montreal.
To complicate matters further, while the aircraft was on the ground in Montreal, a technician inadvertently reactivated the second channel without removing the disabled tag. As a consequence, the fuel gauges remained blank.
Additionally, the aircraft used a metric system for fuel measurement, while pounds per liter was still the standard procedure followed by the fueler who checked the floatstick. The cockpit crew failed to recalculate the value into metric units when entering it into the Flight Management Computer (FMC). Consequently, the aircraft left with only half the required fuel, as the conversion from pounds to kilograms was not accounted for accurately. The same conversion issues occurred during another floatstick test in Ottawa.
Suspended and awarded
Two years after the incident, Captain Pearson and First Officer Quintal were recognized for their exceptional airmanship with the first-ever Fédération Aéronautique Internationale Diploma. This award highlighted their remarkable skills in handling the Gimli Glider incident.
The aircraft, C-GAUN, was repaired in just two days and then flown to Winnipeg for comprehensive repairs. It returned to service with Air Canada, continuing its operation until 2008. Finally, C-GAUN was retired and ultimately stored and partially scrapped at the Mojave Air and Space Port in California.
