Minimum Fuel Requirements for Part 91, 121, 135 Operations
Minimum Fuel Requirements is the regulatory amount of fuel that an aircraft must carry in order to operate any sort of flight. The amount of fuel changes, depending on the aircraft's engine, time, IFR/VFR, and operation.
Aviation regulations is generally separated into three categories:
- Part 91: general aviation
- Part 121: Domestic, Flag, Supplemental Operations
- Part 135: On-demand and Commuter Operations
Part 91
| Type of Operation | Engine | Minimum Fuel Requirements | Regulation |
| VFR Day | Any | Fuel to destination + 30 minutes of reserve fuel at cruising speed | §91.155(a) |
| VFR Night | Any | Fuel to destination + 45 minutes of reserve fuel at cruising speed | §91.155(a) |
| VFR | Rotor-craft | Fuel to destination + 20 minutes of reserve fuel at cruising speed | §91.155(b) |
| IFR | Any | Fuel to destination + fuel to most distant alternate + 45 minutes of reserve fuel at cruising speed | §91.167(a) |
| IFR | Rotor-craft | Fuel to destination + fuel to most distant alternate + 30 minutes of reserve fuel at cruising speed | §91.167(a) |
Part 121
| Type of Operation | Engine | Minimum Fuel Requirements | Regulation |
| IFR Domestic Operations | Any | Fuel to destination + fuel to the most distant alternate + 45 minutes of reserve fuel at cruising speed | §121.639 |
| VFR Domestic Operations | Any | Fuel to destination + fuel to the most distant alternate + 30 minutes of reserve fuel at cruising speed | §121.639 |
| Flag Operations | Non turbine / turbo-propeller | Fuel to destination + fuel to the most distant alternate + 30 minutes and 15% of the total trip time or (90 minutes at cruising speed), whichever is less | §121.641(a) |
| Flag Operations with no suitable alternate | Non turbine / turbo-propeller | Fuel to destination + 3 hours of cruising speed | §121.641(b) |
| IFR Supplemental Operations | Non turbine / turbo-propeller | Fuel to destination + fuel to the most distant alternate + 45 minutes of reserve fuel at cruising speed | §121.643 |
| VFR Supplemental Operations | Non turbine / turbo-propeller | Fuel to destination + fuel to the most distant alternate + 30 minutes of reserve fuel at cruising speed | §121.643 |
| Supplemental Operations outside 48 contiguous US | Non turbine / turbo-propeller | Fuel to destination + fuel to the most distant alternate + 30 minutes and 15% of the total trip time or (90 minutes at cruising speed), whichever is less | §121.643(b) |
| Flag and Supplemental Operations | Turbine | Fuel to destination + fuel to most distant alternate + 10% total trip time + 30 minutes at 1500 ft at alternate airport (or destination) at holding speed | §121.645 |
| Flag and Supplemental Operations with no suitable alternate | Turbine | Fuel to destination + fuel to most distant alternate + 10% total trip time + 2 hour of reserve fuel at cruising speed | §121.645 |
In addition to the minimum fuel, according to §121.647, we must consider factors such as weather, traffic delays, one instrument approach and a missed approach, and any other conditions that an aircraft may face.
Part 135
| Type of Operation | Engine | Minimum Fuel Requirements | Regulation |
| VFR Day | Any | Fuel to destination + 30 minutes of reserve fuel at cruising speed | §135.209 |
| VFR Night | Any | Fuel to destination + 45 minutes of reserve fuel at cruising speed | §135.209 |
| VFR | Rotor-craft | Fuel to destination + 20 minutes of reserve fuel at cruising speed | §135.209(b) |
| IFR | Any | Fuel to destination + fuel to most distant alternate + 45 minutes of reserve fuel at cruising speed | §135.223(a) |
| IFR | Rotor-craft | Fuel to destination + fuel to most distant alternate + 30 minutes of reserve fuel at cruising speed | §91.223(a) |