spierpoint jones,
This issue is indeed adressed by JAA, under JAR-OPS 1.255 Fuel policy
"An operator should base the company fuel policy, including calculation of the amount of fuel to be carried, on the following planning criteria:
[...]
1.3. Contingency fuel, which should be the higher of (a) or (b) below:
a. Either:
i. 5% of the planned trip fuel or, in the event of in-flight replanning, trip fuel for the remainder of the flight; or
ii. Not less than 3% of the planned trip fuel or, in the event of in-flight replanning, trip fuel for the remainder of the flight, subject to the approval of the Authority, provided that an en-route alternate is available; or
[...]"
Salz