W.r.t. '
company dispatcher - also a supposed specialist'....
The difference here, as I understand it, is that in some countries ( especially the USA ) airlines have qualified 'dispatchers' who have some sort of pseudo legal authority and / or responsibility for the despatch ( or not ) of a flight.
In the UK there is ( to my knowledge ) no such equivalent, and the decision to despatch ( or not ) and / or the amount of fuel required is soley down to the legal / nominated commander of the aircraft - and CRM aside, the management of fuel, and indeed the whole filght, rests soley with the commander - wherein it's his/her head on the block when things do not go to 'plan' - alebit a two, or more, crew operation.
The commander is bound by the definitions and requirements laid out in his / her company Operations Manual / Part A / Section 8 ( Operating Procedures ) - it being a CAA / JAA approved / legal document - my own companies version of which is repro'd below for your enlightenment:
8.1.6 Determination of the Quantities of Fuel and Oil Carried
8.1.6.1 Based on the appropriate consumption figures for the stage of flight as contained in Part B of the manual for the specific aeroplane, the fuel on board at the start of each flight must be sufficient to cover the elements listed in the following paragraphs.
8.1.6.2 Standard Procedure
The fuel required is the sum of:
(a)
Taxi Fuel - The total amount of fuel expected to be used prior to take-off including allowances for operation of ice protection systems and APU. (Normally 200kg for the B737).
(b)
Trip Fuel - To include:
(i) Take-off and climb to initial cruising level/altitude, taking into account the expected departure routeing;
(ii) Cruise from top of climb (TOC) to top of descent (TOD), including any step climb/descent;
(iii) TOD to initial approach point, taking into account the expected arrival routeing and procedure;
(iv) Approach and landing at destination.
(c)
Contingency Fuel - Which must be the higher of (i) or (ii) below :
(i) 5% of the planned trip fuel or, in the event of inflight replanning, 5% of the trip fuel for the remainder of the flight; or
(ii) fuel for 5 mins hold at 1500 ft above the destination aerodrome in ISA.
NOTE: At the planning stage not all factors that could have an influence on the fuel used to the destination aerodrome can be foreseen. Consequently contingency fuel is carried to compensate for items such as:
- Deviations of an individual aeroplane from the expected fuel consumption data;
- Deviations from forecast meteorological conditions;
- Deviations from planned routeings and/or cruising levels/altitudes.
(d)
Alternate Fuel - to include:
(i) A go-around from the applicable MDA/DH at the destination aerodrome to missed approach altitude, taking into account the complete missed approach procedure;
(ii) Climb from missed approach altitude to cruising level/altitude;
(iii) Cruise from TOC to TOD;
(iv) TOD to initial approach point taking into account the expected arrival routeing and procedure;
(v) Approach and landing at the destination alternate aerodrome selected in accordance with para 8.1.2.7.
NOTES[list=1][*] If, in accordance with para 8.1.2.8, two destination alternates are required then alternate fuel must be sufficient to cover the case of the alternate requiring the greater amount of fuel.[*] The departure aerodrome may be selected as a destination alternate.[/list=1](e)
Final Reserve Fuel
Fuel to hold for 30 minutes at 1500 ft above aerodrome elevation in ISA calculated with the estimated landing mass on arrival at the alternate or the destination, when no alternate is required.
(f)
Additional Fuel
(to be carried if dictated by the type of operation e.g. ETOPs). This is only required to be carried if the fuel calculated in accordance with (a), (b), (c), (d) and (e) above does not provide sufficient for the circumstances listed below:
(i) holding for 15 mins at 1500 ft above aerodrome elevation in ISA when an IFR flight is being operated without a destination alternate in accordance with para 8.1.3.1; and
(ii) following an engine or pressurisation failure at the most critical point en-route:
- descend as necessary and proceed to an adequate aerodrome; and
- 15 minutes hold at 1500 ft in ISA above the adequate aerodrome; and
- approach and landing.
(g)
Extra fuel
At the discretion of the commander.
8.1.6.3 Decision Point Procedure
When planning to a destination aerodrome via an en-route decision point the fuel required is:
The sum of:[list=a][*] taxi fuel;[*] trip fuel to the destination aerodrome, via the decision point;[*] contingency fuel of not less than 5% of the estimated fuel used from the decision point to the destination aerodrome;[*] alternate fuel, if a destination alternate is required;[*] final reserve fuel;[*] additional fuel, if required; and[*] extra fuel, at the discretion of the commander;[/list=a]
8.1.6.4 Isolated Aerodrome Procedure
When planning to an isolated aerodrome for which an alternate does not exist the fuel required is the sum of:[list=a][*] taxi fuel;[*] trip fuel;[*] contingency fuel in accordance with para 8.1.6.2(c);[*] additional fuel if required, but not less than:
(i) for turbo-prop and turbo-jet aeroplanes fuel to fly for a minimum of two hours, calculated with the normal cruise consumption, after arriving overhead the destination aerodrome, including final reserve fuel; and
(ii) extra fuel, at the discretion of the commander.[/list=a]
8.1.6.5 Predetermined Point Procedure
When planning to a destination alternate where the distance between the destination aerodrome and the
destination alternate is such that a flight can only be routed via a predetermined point to one of these
aerodromes the fuel required is the greater of (a) or (b) below:[list=a][*] the sum of:
(i) taxi fuel;
(ii) trip fuel to the destination aerodrome via the predetermined point;
(iii) contingency fuel in accordance with para 8.1.6.2(c);
(iv) additional fuel if required, but not less than that in para 8.1.6.4(d);
(v) extra fuel, at the discretion of the commander
or,[*] the sum of:
(i) taxi fuel;
(ii) trip fuel from the departure aerodrome to the alternate aerodrome, via the predetermined
point;
(iii) contingency fuel in accordance with para 8.1.6.2(c);
(iv) additional fuel if required, but not less than fuel for 30 mins hold at 1500 ft in ISA including Final Reserve fuel; and
(v) extra fuel, at the discretion of the commander.[/list=a]
8.3.7 Policy and Procedures for In-Flight Fuel Management
8.3.7.1 The commander must ensure that fuel checks are carried out at regular intervals throughout the flight. On flights of more than one hours duration, such checks are to be carried out at not more than hourly intervals. On flights of less than one hour, an intermediate check is to be made at a convenient time when the cockpit workload is low. At each check, the remaining fuel must be recorded and evaluated so as to:[list=a][*] compare actual consumption with planned consumption;[*] check that the fuel remaining will be sufficient to complete the flight; and[*] determine the expected fuel remaining on arrival at the destination.[/list=a]
8.3.7.2 If an in-flight fuel check reveals that the expected fuel remaining on arrival at the destination will be less than the required alternate fuel (para 8.1.6.2(d)) plus final reserve fuel (para 8.1.6.2(e)) the commander will:[list=a][*] assess and take into account the traffic, operational and meteorological conditions prevailing and expected at the destination aerodrome; and[*] similarly along the diversion route to the alternate aerodrome; and[*] similarly at the destination alternate aerodrome;[/list=a]when deciding whether to proceed to the destination aerodrome or to divert, so as to land with not less than final fuel reserve fuel.
8.3.7.3 If an in-flight fuel check reveals that on a flight to an isolated destination aerodrome planned in accordance with para 8.1.6.4, the expected fuel remaining at the point of last possible diversion is less than the sum of:[list=a][*] fuel to divert to an alternate aerodrome selected in accordance with para 8.1.3.1.3;[*] contingency fuel; and[*] final reserve fuel[/list=a]the commander will either:[list=a][*] divert; or[*] continue to the destination provided that two separate runways are available at the destination[/list=a]and the expected weather conditions at the destination comply with those specified for planning in para 8.1.3.1.2.
8.3.7.4 The commander will declare an emergency when the actual usable fuel on board is less than final reserve fuel.