You are right, Flenit, five minutes is the minimum (I have been involved in rewriting an ops manual and in teaching flight planning).
Just to confirm, the following is cut and pasted directly from EU-OPS (yes, I am sad enough to have a copy on my computer) which is far from obsolete:
N.B. paragraph 2 is about using a decision-point procedure to reduce contingency fuel
Appendix 1 to OPS1.255
1.3 Contingency fuel, except as provided for in Paragraph 2 ‘Reduced Contingency Fuel’, which shall be the higher of a. or b. below:
(a) Either:
(i) 5% of the planned trip fuel or, in the event of in-flight re-planning, 5% of the 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 re-planning, 3% of the trip fuel for the remainder of the flight, provided that an en-route alternate aerodrome is available in accordance with Appendix 2 to OPS 1.255; or
(iii) An amount of fuel sufficient for 20 minutes flying time based upon the planned trip fuel consumption provided that the operator has established a fuel consumption monitoring programme for individual aeroplanes and uses valid data determined by means of such a programme for fuel calculation; or
(iv) An amount of fuel based on a statistical method approved by the Authority which ensures an appropriate statistical coverage of the deviation from the planned to the actual trip fuel. This method is used to monitor the fuel consumption on each city pair/aeroplane combination and the operator uses this data for a statistical analysis to calculate contingency fuel for that city pair/aeroplane combination.
(b) An amount to fly for 5 minutes at holding speed at 1500 ft (450 m), above the destination aerodrome in Standard Conditions.
frontlefthamster
I think they do under EU-OPS. Some parts are the primary legal restriction for the subject they cover. For example CAP 371 is no longer legally binding, so the operator's FTL scheme must be approved, and that is in the Ops Manual. I might be wrong, but if so it would surprise me. They certainly made enough fuss about the layout of teh one I helped rewrite!