JF Mezei wrote:

On 2016-09-21 04:11, Rob wrote:

While I understand that weight of fuel is more significant to performance
of the aircraft than volume,


Needed to determine how much luggage/cargo can be loaded on aircraft,
calculate centre of gravity and the V1/V2 speeds during takeoff.


Not just that. Fuel consumption is usually given in pounds of fuel in
the performance manuals.


For flight length, either will work because computer can display "pounds
per hour" or "litres per hour" for fuel consumption. But for takeoff,
the plane's specs are in weight.


You don't just say 'fill er up' and go fly. The quantity of fuel
required for the flight (and diverts) is calculated before fueling.
Performance figures are in MASS of fuel required. It doesn't matter
what the airplane can display in.



I find it confusing that the two are being
used in parallel, and manual conversions are being made by pilots and
ground personnel.


In the case of the Gimli glider, pilots *should* have known that if they
want 22 pounds of fuel, the rough equivalent would have been 10 litres.


It's 12.5 litres, not 10 litres.


And since fuel is lighter than water, the number of litres should have
been north of 10. So if their math yielded 5 litres they *should* have
seen a problem.


Except we're not talking about little numbers like 5-10 litres here...


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn