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Old May 20th 06, 04:39 PM posted to rec.aviation.piloting
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Default Jet fuel A-1 specific gravity

Roy Smith wrote:

Google for "gimli glider" and I'm sure you'll find it. In a nutshell,
an airline flight crew got confused between metric and english units
when ordering fuel, took on less than they expected, and ran out of
gas in flight, and dead-sticked it to an abandoned military airfield
in Gimli, Manitoba.

Opinion varies on whether the flight crew were total idiots for
committing the unpardonable sin of running out of gas, or heros for
managing to get the plane on the ground with no injuries and only
minor damage to the aircraft. Personally, I fall into the first camp.


Of course the story was much more involved than that. It included a
series of mistakes or omissions on the part of a number of people. If any
one of the mistakes had not taken place, the incident would not have
happened. When you look at the whole story, the captain was only one
player in the drama, but was expected by many to figuratively go down
with his ship.

Let's see if I can remember the essence:

- The airline purchased the 767 with the fuel gauges calibrated in metric
units. It was their first aircraft model with non-English units.

- The dual channel fuel gauges started to give trouble about 3 weeks
before the incident, but failed at Edmonton, prior to a scheduled trip to
Montreal. Both circuit breakers would pop if the power was turned off
and on, and while the tech did not have replacement modules, he found
that he could set up one channel, leaving the breaker for the other
channel off, and the breaker for the working channel would hold. It was
because of a poor solder joint and a design problem with the fallback
arrangment of the system.

- The airline's MEL would allow the aircraft to proceed with the one
channel operative, supported by a drip test of the tanks to confirm the
fuel quantity. (Some reports I read said that the MEL even allowed the
aircraft to proceed with only the drip test, and no operative gauges.)

- On arrival in Montreal, a well-meaning, but unauthorized tech tried to
run the self-test of the fuel management system, with the result that the
circuit breakers on both channels popped, disabling the system
completely. That fact was not reported to the maintenance supervisor.

- The supervisor, thinking that the aircraft was in the same condition as
when it arrived, approved the aircraft departure with the drip test, not
realizing that neither fuel gauge was working.

- The captain did not have a current MEL, as the aircraft were so new and
so many changes had been made to the MEL (55 in three months) that the
airline had not issued them to the crews. The maintenance supervisor was
the only one with the current MEL. The captain confirmed that he could
depart, not mentioning the non-working gauges, and was told it was OK
with the drip test.

- The flight crew calculated the weight of fuel needed for the flight,
and the fueler converted that to liters (the fuel truck meters were in
liters) using the wrong fuel density (lb. per liter, instead of kg per
liter.) He dripped the tanks, calculated how many liters needed to be
added, rechecked the drip after adding what he thought was the required
fuel, and reported everything on a fuel slip provided to the flight crew.

- The captain felt there was something wrong, and questioned the density
number used and noted on the fuel slip. The first officer confirmed that
the number was what he remembered. As I recall, there was an off-duty
company pilot that also confirmed the number. The captain had the
refueler recheck the whole test twice, and was given the same results
each time. In short, he had less than 1/2 the fuel he needed for the
flight. (The ratio of pounds to kilograms)

- The fueler didn't know the flight's final destination, so didn't
question the quantities. He only knew the aircraft was making a short 100
mile hop to the first stop at Ottawa, where the flight normally topped
up, and for which there was certainly adequate fuel. The captain had
instead decided to take on fuel for the whole trip to Edmonton, to try to
catch up on the schedule after a late start, and avoid the top-up in
Ottawa.

- On takeoff, the captain felt that the aircraft felt light for the
expected fuel load, and decided to have the tanks tested again at the
first stop in Ottawa. The refueller did the same drip tests, used the
same incorrect fuel density for the calculation, and presented the crew
with a slip with yet another incorrect fuel reading.

So how much was the captain really to blame for the problems? Under the
airline's rules, with no flight engineer, the maintenance forces were
responsible for proper fueling. The flight crew only provided the
required weight, and confirmed it with the fuel gauges. With no fuel
gauges, they hadn't been trained in how to confirm the drip tests, and
had never been provided with the proper fuel density for metric
measurement. The captain had the tests repeatedly made at two different
airports, and was presented with consistent, but also incorrect,
information.

The official report placed primary blame on the lack of training provided
the refuelers, maintainers and flight crews on the new aircraft. There
was also criticism of procedures, the control and distribution of manuals
and documents, and so on. The airline suspended the captain for a time,
but public pressure forced them to reinstate him. He did not attract
primary blame in the accident report, and continued to fly for the
airline until normal retirement.