Crash Course in Density
As flight 143, a twin engine 767, was passing over Red Lake on its was
to Edmonton, Canada, the left front fuel pump warning light went on. There were
a few possibilities for this to happen, such as the fuel pump failing, a fuel
line clogging, or a empty fuel tank. The former two were easily dealt with,
since the plane could fly without one fuel pump. However, the last possibility
was horrifying. After a few minutes, the second fuel pump in the left wing
began to blare. It would be too much of a coincidence for two fuel pumps to
independently fail, or two fuel lines to independently clog, so it was apparent
that the left tank was out of fuel. Quickly, the pilots decided that getting to
Edmonton was out of the question. The nearest large airport was at Winnipeg, so
they radioed ahead and changed their course. In a few minutes, all four of the
fuel pumps had failed. The worst possible news, they were out of fuel. In a
few more minutes the engines stopped running, and all of the high tech
instruments became useless.
They realized that they could not even make it to Winnipeg. Their only
chance was an abandoned to a abandoned Air Force airstrip. Unfortunately, the
airstrip had been converted to a race track, complete with race cars, fences,
and spectators. The 767 crash landed, and, fortunately, no one was killed.
Their were many contributing factors that made this plane run out of
fuel. First of all, the computerized fuel gauge was not working, and a
maintenance worker said , incorrectly, that the plane was still certified to fly.
To measure the amount of fuel remaining, they use a drip stick method. They
discovered that their was 7 682 liters in the tank. However, they had always
measured fuel in the past as pound, while the 767 consumed fuel in kilograms.
The drip sticks did not express the amount of fuel in pounds or kilograms, but
in liters. It seems to be a simple matter of conversion to arrive a the answer.
All they needed to know was how many kilograms were in a liter. Someone said
1.77, and they calculated the value they needed. However, the conversion of
1.77 was not Kilograms per liter, but pounds per liter. The actual value it .
803. They were off by more than 50%. This problem would have been avoided if
they had kept track of the units during the conversion. That is why it is
always important to keep track of the units.