I remember reading in Reader Digest how when shortly after Canada went to the metric system it resulted in the under fueling of a jet liner that then ran out of fuel as 30 thousands feet.
Somehow the pilots manage to do a dead stick landing at an old airport that was being use as a race track at the time of the landing.
So converting from one system to another almost got a few hundreds people kill.
Here it is and I love google and the internet.........
Gimli Glider From Wikipedia, the free encyclopediaJump to: navigation, search Air Canada Flight 143
Air Canada flight 143 landed on an auto dragstrip at Gimli, Manitoba
Date 23 July 1983
The Gimli Glider is the nickname of an Air Canada aircraft that was involved in a notable aviation incident in July 1983. On 23 July, Air Canada Flight 143, a Boeing 767-200 jet, ran out of fuel at an altitude of 41,000 feet (12,500 m) ASL, about halfway through its flight from Montreal to Edmonton via Ottawa. The crew was able to glide the aircraft safely to an emergency landing at Gimli Industrial Park Airport, a former Canadian Air Force base at Gimli, Manitoba.
The subsequent investigation revealed corporate failures and a chain of minor human errors that combined to defeat built-in safeguards. In addition, fuel loading was miscalculated through misunderstanding of the recently adopted metric system, which replaced the imperial system.
Running out of fuelAt 41,000 feet (12,500 m), 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 would still feed fuel to the aircraft's two engines. The aircraft's fuel gauges were inoperative. However, the flight management computer indicated that there was still sufficient fuel for the flight, but, as the pilots subsequently realized, the entry calculation was incorrect. 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, 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 – that would indicate the rate at which the aircraft was descending and therefore how long 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 speed means a decrease in the power available to control the aircraft.
 Landing at GimliIn 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, 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 sites, he needed to fly the 767 at the "best glide ratio 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 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 feet (1,500 m) in 10 nautical miles (19 km; 12 mi), 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 landing at the former RCAF Station Gimli, a closed air force base where he had once served as a Canadian Air Force pilot. Unknown to him, however, part of the facility had been converted to a race track complex, now known as Gimli Motorsports Park. It includes a road race course, a go-kart track, and a dragstrip. Furthermore, a CASC amateur sports car race was underway that day and the area around the decommissioned runway was full of cars and campers. Part of the decommissioned runway itself was being used to stage the 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, making the aircraft increasingly difficult to control because of the reduced power being generated.
As the runway drew nearer, it became apparent that the aircraft was too high and fast, raising the danger of running off the runway before the aircraft could be stopped. The lack of hydraulic pressure prevented flap/slat extension. These devices are used under normal landing conditions to reduce the stall speed of the aircraft for a safe landing. The pilots briefly considered executing a 360 degree turn to reduce speed and altitude, but decided that they did not have enough altitude for the maneuver. Pearson decided to execute a forward slip to increase drag and lose altitude. This maneuver is commonly used with gliders and light aircraft to descend more quickly without gaining forward speed.
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 well, causing the aircraft's nose to scrape along the ground. The plane also slammed into the guard rail now separating the strip, which helped slow it down.
None of the 61 passengers were seriously hurt. A minor fire in the nose area was extinguished 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, which were not long enough to accommodate the increased height. These were treated by a doctor who had been about to take off in an aircraft on Gimli's remaining runway.
 InvestigationAn Air Canada investigation concluded that the pilots and mechanics were at fault, although the Aviation Safety Board of Canada (predecessor of the modern Transportation Safety Board of Canada) found the airline at fault.
The safety board reported that Air Canada management was responsible for "corporate and equipment deficiencies". The report praised the flight and cabin crews for their "professionalism and skill". It noted that Air Canada "neglected to assign clearly and specifically the responsibility for calculating the fuel load in an abnormal situation", finding that the airline had failed to reallocate the task of checking fuel load that had been the responsibility of the flight engineer on older (three-crew) aircraft.
 Fuel quantity indicator systemThe amount of fuel in the tanks of a Boeing 767 is computed by the Fuel Quantity Indicator System (FQIS) and displayed in the cockpit. The FQIS on the incident aircraft was a dual-processor channel, each calculating the fuel independently and cross-checking with the other. In the event of one failing the other could still operate alone, but under these circumstances the indicated quantity was required to be cross-checked against a floatstick measurement before departure. In the event of both channels failing there would be no fuel display in the cockpit, and the aircraft would be considered unserviceable and not authorized to fly.
After inconsistencies were found with the FQIS in other 767s, Boeing issued a service bulletin for the routine checking of this system. An engineer in Edmonton duly did so when the aircraft arrived from Toronto following a trouble-free flight the day before the incident. While conducting this check, the FQIS failed and the cockpit fuel gauges went blank. The engineer had previously encountered the same problem earlier in the month when the same aircraft had arrived, again from Toronto, with an FQIS fault. He found then that disabling the second channel by pulling the circuit breaker in the cockpit restored the fuel gauges to working order albeit with only the single FQIS channel operative. In the absence of any spares he simply repeated this temporary fix by pulling and tagging the circuit breaker.
A record of all actions and findings was made in the maintenance log, including the entry; "SERVICE CHK – FOUND FUEL QTY IND BLANK – FUEL QTY #2 C/B PULLED & TAGGED...". This reports that the fuel gauges were blank and that the second FQIS channel was disabled, but does not make clear that the latter fixed the former.
On the day of the incident, the aircraft flew from Edmonton to Montreal. Before departure the engineer informed the pilot of the problem and confirmed that the tanks would have to be verified with a floatstick. In a misunderstanding however the pilot believed that the aircraft had been flown with the fault from Toronto the previous afternoon. That flight proceeded uneventfully with fuel gauges operating correctly on the single channel.
On arrival at Montreal, there was a crew change for the return flight back to Edmonton. The outgoing pilot informed Captain Pearson and First Officer Quintal of the problem with the FQIS and passed along his mistaken belief that the aircraft had flown the previous day with this problem. In a further misunderstanding, Captain Pearson believed that he was also being told that the FQIS had been completely unserviceable since then.
While the aircraft was being prepared for its return to Edmonton, a maintenance worker decided to investigate the problem with the faulty FQIS. In order to test the system he re-enabled the second channel, at which point the fuel gauges in the cockpit went blank. He was called away to perform a floatstick measurement of fuel remaining in the tanks. Distracted, he failed to disable the second channel, leaving the circuit breaker tagged (which masked the fact that it was no longer pulled). The FQIS was now completely unserviceable and the fuel gauges were blank.
On entering the cockpit, Captain Pearson saw what he was expecting to see: blank fuel gauges and a tagged circuit breaker. He consulted the aircraft's Minimum Equipment List (MEL), which told him that the aircraft could not be flown in this condition. However, the 767 was still a very new aircraft, having flown its maiden flight in September 1981. C-GAUN was the 47th Boeing 767 off the production line, delivered to Air Canada less than 4 months previously. In that time there had been 55 changes to the MEL, and some pages were still blank pending development of procedures.
As a result of this unreliability, it had become practice for flights to be authorised by maintenance personnel. To add to his own misconceptions about the condition the aircraft had been flying in since the previous day, reinforced by what he saw in the cockpit, he now had a signed-off maintenance log that it had become custom to prefer above the Minimum Equipment List.
 RefuelingAt the time of the incident, Canada was converting to the metric system. As part of this process, the new 767s being acquired by Air Canada were the first to be calibrated for the new system, using litres and kilograms instead of gallons and pounds. All other aircraft were still operating with Imperial units (gallons and pounds). For the trip to Edmonton, the pilot calculated a fuel requirement of 22,300 kilograms (49,000 lb). A dripstick check indicated that there were 7,682 litres (1,690 imp gal; 2,029 US gal) already in the tanks. In order to calculate how much more fuel had to be added, the crew needed to convert the quantity in the tanks to a weight, subtract that figure from 22,300 and convert the result back into a volume. (In previous times, this task would have been completed by a flight engineer, but the 767 was the first of a new generation of airliners that made this position redundant.)
A litre of jet fuel weighs 0.803 kg, so the correct calculation was:
7682 litres × 0.803 = 6169 kg
22300 kg − 6169 kg = 16131 kg
16131 kg ÷ 0.803 = 20088 litres of fuel to be transferred
Between the ground crew and flight crew, however, they arrived at an incorrect conversion factor of 1.77, the weight of a litre of fuel in pounds. This was the conversion factor provided on the refueller's paperwork and which had always been used for the rest of the airline's imperial-calibrated fleet. Their calculation produced:
7682 litres × 1.77 = 13597 kg
22300 kg − 13597 kg = 8703 kg
8703 kg ÷ 1.77 = 4916 litres of fuel to be transferred
Instead of 22,300 kg of fuel, they had 22,300 pounds on board — only a little over 10,000 kg, or less than half the amount required to reach their destination. Knowing the problems with the FQIS, Captain Pearson double-checked their calculations but was given the same incorrect conversion factor. He checked their arithmetic, inevitably coming up with the same erroneous figures.
The Flight Management Computer (FMC) measures fuel consumption, allowing the crew to keep track of fuel burned as the flight progresses. It is normally updated automatically by the FQIS, but in the absence of this facility it can be updated manually. Believing he had 22,300 kg of fuel on board, this is the figure the captain entered.
Because the FMC would reset during the stopover in Ottawa, the captain had the fuel tanks measured again with the dripstick while there. In converting the quantity to kilograms, the same incorrect conversion factor was used, leading him to believe he now had 20,400 kg of fuel; in reality, he had less than half the required amount.
 AftermathFollowing Air Canada's internal investigation, Captain Pearson was demoted for six months, and First Officer Quintal was suspended for two weeks. Three maintenance workers were also suspended. Nevertheless, in 1985 the pilots were awarded the first ever Fédération Aéronautique Internationale Diploma for Outstanding Airmanship. Several attempts by other crews who were given the same circumstances in a simulator at Vancouver resulted in simulated crashes. Quintal was promoted to Captain in 1989, while Pearson retired in 1993.
C-GAUN, Air Canada fin number 604, was temporarily repaired at Gimli and flew out two days later to be fully repaired at a maintenance base in Winnipeg. It remained in service with Air Canada until almost a quarter-century later. Following the successful appeal of their suspensions, Pearson and Quintal were assigned as crew members aboard another Air Canada flight. As they boarded the aircraft, it became apparent that the aircraft was the same one that was involved in the Gimli incident, and they lightly joked about not repeating the performance. Shortly after takeoff, a low fuel warning did sound; however, it was a false alarm from a defective warning system, and the flight continued uneventfully to its destination. After 25 years of service, the airplane flew its last revenue flight on 1 January 2008. Air Canada still uses Flight 143 for its Montreal-Ottawa-Edmonton route using an Embraer