Re: How do fuel guages work?

From: (Mark Brader)
Organization: SoftQuad Inc., Toronto, Canada
Date:         06 Sep 95 01:04:09 
References:   1 2 3
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Jay Vassos-Libove ( writes:

> This incident became known as the Gimli Glider.  The 767 was
> misfueled because all of its fuel gauges were ... malfunctioning ...
> ... the aircraft was fueled with checks done by converting
> a dipstick measurement in the tanks from a linear (probably metric)
> measurement to a volumetric (english, since it was a 767)
> measurement... and somebody got a conversion factor exactly
> backwards, resulting in *4 instead of /4, so they put 1/4 the
> necessary fuel on board.

That would be 1/16, wouldn't it?

What really happened, though, was that they converted *correctly* from
the linear to the volume measure, but got the conversion to *weight*
(or mass) wrong.  They had to multiply by the correct density for the
day's temperature, and inadvertently took the density in the same units
used for most other planes.  The flight then took off with X pounds of
fuel, but since it was an Air Canada 767, it should have been X kilograms.
It was therefore underfueled by about 55%.
Mark Brader,         "Men!  Give them enough rope and they'll dig
SoftQuad Inc., Toronto           their own grave."    -- EARTH GIRLS ARE EASY

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