Just for clarification - the definition of Fuel Over Destination our company uses is:
The quantity of fuel planned to be remaining at 1,500ft at the destination airport. It equals Preflight Fuel Order minus Taxi and Flight Fuel.
So the planned fuel over head will be FFR (fixed fuel reserve) + VFR + Approach Fuel (1500' overhead to touchdown).
For the 737 -400/800 - approach fuel used is 300kg.
(So I think from memory FFR is approx 1.1 tonnes + VFR + 300kg, which will usually be less than 2.5 tonnes. So he difference would be contingency or planned additional to bring the figure up to 2.5 tonnes overhead)
Of course if weather dictates an alternate then that will be included - but we do not carry automatically carry alternates if the Wx is ok.
I believe our company tried to implement LIDO - but our fuel policy is so different that LIDO couldnt be adapted.....
(As an aside they did a sim exercise arriving over destination with 2500KG - and gave a gear problem during approach- (main gear on 1 side wouldnt come down) - 2500kg- gives you virtually no time to troubleshoot. Basically you have time to run the checklist and set up for the next approach with the gear still partially jammed up - committed to partial gear up landing. Hardly any time to prepare the cabin...... whilst the outcome may be the same with extra fuel - it certainly is not a comfortable feeling knowing you couldnt trouble shoot or have more time to prepare the cabin.)
It certainly made me want to arrive with a bit more than 2500kg.