running on empty

Posted on August 28, 2008
Filed Under history | Leave a Comment

Truly, the fight from hell…

from wikipedia

“On 22 July 1983, the day before the incident flight, Air Canada’s Boeing 767  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 via Ottawa, with Captain Robert (Bob) Pearson and First Officer Maurice Quintal at the controls

At 12,500 m (41,000 feet), over Red Lake, Ontario, 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 it off, as gravity would still feed fuel to the aircraft’s two engines. The aircraft’s computer indicated that there was still sufficient fuel for the flight, but, as subsequently realized, the calculation was based on incorrect settings. A few moments later, a second fuel pressure alarm sounded, 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, this time with a long “bong” that no one present could recall having heard before. This was the “all engines out” sound, an event that had never been simulated during training.Seconds later, most of the instrument panels in the cockpit went blank as the right-side engine also stopped and the 767 lost all power.

The 767 was one of the first airliners to include an Electronic Flight Instrument System (EFIS), a system that required the electricity generated by the aircraft’s jet engines in order to operate. With both engines stopped, therefore, the system went dead, leaving only a few basic battery-powered emergency flight instruments. While these provided basic but sufficient information with which to land the aircraft, a vertical speed indicator – which would indicate the rate at which the aircraft was sinking and therefore how far it could glide unpowered – was not among them.

In 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. As with the 767, this is usually achieved through the automated deployment of a ram air turbine, a generator driven by a small propeller, which in turn is driven by the forward motion of the aircraft. As the Gimli pilots were to experience on their landing approach, a decrease in this forward motion 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 8500 m (28,000 feet) when the second of their two engines stopped. They immediately searched their emergency checklist for the section on flying the aircraft with both engines stopped, only to find that no such section existed.[4] Captain Pearson, however, was an experienced glider pilot, which gave him familiarity with some flying techniques almost never used by commercial pilots. In order to have the maximum range and therefore the largest choice of possible landing site, he needed to fly the 767 at a speed known as the “best glide ratio speed”. Making his best guess as to this speed for the 767, he flew the aircraft at 220 knots (407 km/h). First Officer Maurice Quintal began making calculations to see if they could reach Winnipeg. He used the altitude from one of the mechanical backup instruments, while the distance traveled was supplied by the air traffic controllers in Winnipeg, measuring the distance the aircraft’s echo moved on their radar screens. The aircraft had lost 5,000 ft in 10 nautical miles (1.5 km in 18½ km), giving a glide ratio of approximately 12:1. The controllers and Quintal both calculated that Flight 143 would not make it to Winnipeg.

At this point, Quintal proposed his former airforce base at Gimli as a landing site. Unknown to him, however, the base had become a dragstrip and had decommissioned one of its runways. As a result of the runway’s conversion to use as a dragstrip, the runway had been converted into two lanes with a guard rail running down the middle of it. Furthermore, a “Family Day” was underway at the dragstrip that particular day and the area around the decommissioned runway was covered with cars and campers. The decommissioned runway itself was being used to stage a race.

Without power, the pilots had to try lowering the aircraft’s main landing gear via a gravity drop, but, due to the airflow, the nose wheel failed to lock into position. The decreasing forward motion of the aircraft also reduced the effectiveness of the Ram Air Turbine (RAT), making the aircraft increasingly difficult to control because less power was generated. As the runway drew nearer, it became apparent that the aircraft was too high, prompting Pearson to execute a maneuver known as a forward slip to increase their drag and reduce their altitude. At the time Pearson executed the slip, the aircraft was flying over a golf course, and one passenger reportedly said “Christ… I can almost see what clubs they’re using!”.[4] A forward slip is commonly used with gliders and light aircraft to descend more quickly.

As soon as the wheels touched the runway, Pearson “stood on the brakes”, blowing out two of the aircraft’s tires. The unlocked nose wheel collapsed and was forced back into its housing, causing the aircraft’s nose to scrape along the ground. The plane slammed into a guard rail which made the plane lose a bit more speed to stop it from flying off the runway.

None of the 61 passengers were seriously hurt during the landing. A minor fire in the nose area was soon put out by racers and course workers armed with fire extinguishers. As 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. These were tended by a doctor who had been about to take off in an aircraft on Gimli’s remaining runway.

Coincidentally, the mechanics sent out to Gimli from Winnipeg Airport were left stranded when their van ran out of fuel.[5] Another was sent to pick them up.


Leave a Reply