The minimum amount of fuel a passenger jet must carry is established by regulatory bodies such as EASA and FAA. Airlines are actually required to carry far more fuel for a flight than it takes to get from A to B in the event of the unexpected, such as an airport closure or an emergency plane. Commercial flights typically carry at least an hour of extra fuel on top of that needed to get to their destination, but this is often increased by pilots depending on the circumstances of the day.
Airlines must comply with regulatory provisions concerning the transportation of fuel. Most authorities’ policies are broadly similar and are detailed in each airline’s operations manuals.
Under EASA regulations (although the FAA and other authorities are very similar), the captain must ensure that he has the following minimum fuel available before departure:
- travel fuel
- Diversion fuel or 15 minute fuel hold if the flight is scheduled without alternation
- Reserve fuel
- emergency fuel
- taxi fuel
- Additional fuel
Fuel required from start of takeoff, through climb, cruise, descent and approach to touchdown at destination, assuming departure on SID from assumed runway and arrival using the STAR for the assumed arrival runway and a route based on the forecast wind.
Fuel required for go-around at destination, climb, cruise, descent, approach and landing at the selected alternate airport. This is normally calculated at the expected landing weight minus emergency fuel.
If no alternative is provided for the flight, the diversion fuel figure should be changed to 15 minutes fuel hold at 1500 feet above the destination airfield under standard conditions.
Is the minimum fuel required to be present in the tanks at the alternate aerodrome (or at destination if there is no planned alternate). The figure is calculated on the basis of 30 minutes of fuel holding at 1500 feet in a configuration specific to the planned landing weight.
This is done to cover unforeseen deviations from the planned operation. For example, winds/temperatures different from forecast or ATC restrictions on levels and speed. It can be used at any time after dispatch (once the aircraft is moving under its own power). It cannot be expected to use it before. More likely it is used for departure or arrival delays.
The emergency fuel must be the greater of (i) or (ii) below:
I. That is:
a. No less than 5% of TRAVEL FUEL required from departure to destination; Where
b. If en-route relief is available and selected, not less than 3% of the TRIP FUEL required from departure to destination; Where
vs. A quantity of fuel sufficient for 20 minutes of flight according to the fuel consumption planned for the trip; Where
D. Statistical Emergency Fuel (SCF).
ii. An amount to fly for 5 minutes at a steady speed at 1500 feet proper to the expected landing weight.
The minimum emergency fuel to be carried must not be less than 5 minutes at a holding speed at 1500 feet appropriate to the expected landing weight, even for the purpose of LMC fuel reduction
This is fuel for burning the APU on the ground, starting the engine and taxiing. Most airlines use statistical data to calculate this using taxi time in minutes.
Additional fuel is planned and loaded if the total existing fuel is not sufficient to respond to an engine failure (2 engines in a 4 engine aircraft) or depressurization at the most critical point along the route. Fuel planning must allow for a descent and a Fuel trip to an alternate airfield, hold for 15 minutes at 1500 feet and make an approach and land.
Most airlines will use the total required fuel, which is presented to pilots, through their flight planning system. Pilots will then decide if they need “extra” fuel. There can be many reasons for the request for additional fuel, such as weather conditions, ATC delays, an increase in the number of passengers or a technical fault.
The final decision on how much fuel to carry for a flight is always the responsibility of the aircraft captain. The captain will discuss with the co-pilot the additional fuel requirements before the start of the flight.