The in-flight remaining fuel must be sufficient to proceed to an airport where a safe landing can be made, with the final reserve fuel still remaining on landing. 

This regulation applies to the destination airport, the destination alternate airport, as well as to any en route alternate airport. 

Note: The Captain shall declare an emergency when: 

Actual fuel on board ≤ Final reserve 

1.2.2. Minimum Fuel at Destination Airport 

1.2.2.1. With a Destination Alternate Airport 

The pilot must arrive over the destination with enough fuel to ensure flight safety. 

The following illustrates a standard arrival profile. 

The minimum regulatory fuel above the destination threshold shall be the minimum amount of fuel enabling the aircraft to reach the alternate airport. It is defined as follows: 

Minimum fuel at destination (with alternate) = Alternate fuel + Final reserve fuel 

If the expected remaining fuel on arrival at the destination airport is less than the alternate fuel plus the final reserve, the Captain must consider the prevailing traffic and operational conditions at the destination airport, along the diversion route to the destination alternate airport, when deciding whether to go on to the destination, or to divert. 

1.2.2.2. Without Destination Alternate Airport 

In this case, the minimum fuel remaining on board at landing shall be the Final Reserve Fuel. 

Minimum fuel at destination (without alternate) = Final reserve (2 hours) 

1.2.2.3. Max Holding Time above Destination Airport 

. Available Holding Fuel 

Holding is possible, when the remaining fuel above the destination airport is more than the minimum fuel at destination, plus the fuel for approach. 

Available fuel for holding on arrival = Remaining fuel at destination - (alternate fuel + final reserve + approach) 

Maximum Holding Time 

From the available holding fuel and the holding hourly consumption, the holding time is obtained as follows: 

Available fuel for holding

t = Holding hourly consumption 

2. FAR - FUEL PLANNING AND MANAGEMENT 

2.1. Different Types of Operations 

Three cases have to be taken into account: 

Domestic Operations 

Between any points within the 48 contiguous States of the United States or the District of Columbia; or 

Operations solely within the 48 contiguous States of the United States or the District of Columbia; or Operations entirely within any State, territory, or possession of the United States; or 

When specifically authorized by the Administrator, operations between any point within the 48 contiguous States of the United States or the District of Columbia and any specifically authorized point located outside the 48 contiguous States of the United States or the District of Columbia. 

Flag Operations 

Between any point within the State of Alaska or the State of Hawaii or any territory or possession of the United States and any point outside the State of Alaska or the State of Hawaii or any territory or possession of the United States, respectively; or 

Between any point within the 48 contiguous States of the United States or the District of Columbia and any point outside the 48 contiguous States of the United States and the District of Columbia. 

Between any point outside the U.S. and another point outside the U.S. 

Supplemental Operations 

Operations for which the departure time, departure location, and arrival location are specifically negotiated with the customer or the customer's representative. 

All-cargo operations. 

2.2. Fuel Policy 

The required fuel quantity for a safe trip along the planned route is calculated for each flight. Each operator has its own fuel policy. This policy is based on the loading of minimum regulatory fuel requirements (FAR 121). 

2.2.1. Domestic Operations 

“FAR 121.639 No person may dispatch or take off an airplane unless it has enough fuel--

(a) To fly to the airport to which it is dispatched 

(b) Thereafter, to fly to and land at the most distant alternate airport (where required) for the airport to which dispatched; and 

(c) Thereafter, to fly for 45 minutes at normal cruising fuel consumption.” 

The minimum fuel quantity (Q) calculated for domestic operation is defined as: 

Q = taxifuel + TF + AF + FR 

Where: 

 TF = Trip fuel 

 AF = Alternate fuel 

 FR = Final reserve fuel