---
kind: "range"
citation: "14 C.F.R. §§ 121.639–121.647"
title: "14"
from: "121.639"
to: "121.647"
count: 6
url: "https://uscodex.org/cfr/14/121.639..121.647"
---

# §121.639. Fuel supply: All domestic operations.


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 or, for certificate holders who are authorized to conduct day VFR operations in their operations specifications and who are operating nontransport category airplanes type certificated after December 31, 1964, to fly for 30 minutes at normal cruising fuel consumption for day VFR operations.

# §121.641. Fuel supply: Nonturbine and turbo-propeller-powered airplanes: Flag operations.

- (a) No person may dispatch or take off a nonturbine or turbo-propeller-powered airplane unless, considering the wind and other weather conditions expected, it has enough fuel—
  - (1) To fly to and land at the airport to which it is dispatched;
  - (2) Thereafter, to fly to and land at the most distant alternate airport specified in the dispatch release; and
  - (3) Thereafter, to fly for 30 minutes plus 15 percent of the total time required to fly at normal cruising fuel consumption to the airports specified in [paragraphs (a)](#a) (1) and (2) of this section or to fly for 90 minutes at normal cruising fuel consumption, whichever is less.
- (b) No person may dispatch a nonturbine or turbo-propeller-powered airplane to an airport for which an alternate is not specified under [§ 121.621(a)(2)](/cfr/14/121.621.md?p=a-2), unless it has enough fuel, considering wind and forecast weather conditions, to fly to that airport and thereafter to fly for three hours at normal cruising fuel consumption.

# §121.643. Fuel supply: Nonturbine and turbo-propeller-powered airplanes: Supplemental operations.

- (a) Except as provided in [paragraph (b)](#b) of this section, no person may release for flight or takeoff a nonturbine or turbo-propeller-powered airplane unless, considering the wind and other weather conditions expected, it has enough fuel—
  - (1) To fly to and land at the airport to which it is released;
  - (2) Thereafter, to fly to and land at the most distant alternate airport specified in the flight release; and
  - (3) Thereafter, to fly for 45 minutes at normal cruising fuel consumption or, for certificate holders who are authorized to conduct day VFR operations in their operations specifications and who are operating nontransport category airplanes type certificated after December 31, 1964, to fly for 30 minutes at normal cruising fuel consumption for day VFR operations.
- (b) If the airplane is released for any flight other than from one point in the contiguous United States to another point in the contiguous United States, it must carry enough fuel to meet the requirements of [paragraphs (a)](#a) (1) and (2) of this section and thereafter fly for 30 minutes plus 15 percent of the total time required to fly at normal cruising fuel consumption to the airports specified in [paragraphs (a)](#a) (1) and (2) of this section, or to fly for 90 minutes at normal cruising fuel consumption, whichever is less.
- (c) No person may release a nonturbine or turbo-propeller-powered airplane to an airport for which an alternate is not specified under [§ 121.623(b)](/cfr/14/121.623.md?p=b), unless it has enough fuel, considering wind and other weather conditions expected, to fly to that airport and thereafter to fly for three hours at normal cruising fuel consumption.

# §121.645. Fuel supply: Turbine-engine powered airplanes, other than turbo propeller: Flag and supplemental operations.

- (a) Any flag operation within the 48 contiguous United States and the District of Columbia may use the fuel requirements of [§ 121.639](/cfr/14/121.639.md).
- (b) For any certificate holder conducting flag or supplemental operations outside the 48 contiguous United States and the District of Columbia, unless authorized by the Administrator in the operations specifications, no person may release for flight or takeoff a turbine-engine powered airplane (other than a turbo-propeller powered airplane) unless, considering wind and other weather conditions expected, it has enough fuel—
  - (1) To fly to and land at the airport to which it is released;
  - (2) After that, to fly for a period of 10 percent of the total time required to fly from the airport of departure to, and land at, the airport to which it was released;
  - (3) After that, to fly to and land at the most distant alternate airport specified in the flight release, if an alternate is required; and
  - (4) After that, to fly for 30 minutes at holding speed at 1,500 feet above the alternate airport (or the destination airport if no alternate is required) under standard temperature conditions.
- (c) No person may release a turbine-engine powered airplane (other than a turbo-propeller airplane) to an airport for which an alternate is not specified under [§ 121.621(a)(2)](/cfr/14/121.621.md?p=a-2) or [§ 121.623(b)](/cfr/14/121.623.md?p=b) unless it has enough fuel, considering wind and other weather conditions expected, to fly to that airport and thereafter to fly for at least two hours at normal cruising fuel consumption.
- (d) The Administrator may amend the operations specifications of a certificate holder conducting flag or supplemental operations to require more fuel than any of the minimums stated in paragraph [(a)](#a) or [(b)](#b) of this section if he finds that additional fuel is necessary on a particular route in the interest of safety.
- (e) For a supplemental operation within the 48 contiguous States and the District of Columbia with a turbine engine powered airplane the fuel requirements of [§ 121.643](/cfr/14/121.643.md) apply.

# §121.646. En-route fuel supply: flag and supplemental operations.

- (a) No person may dispatch or release for flight a turbine-engine powered airplane with more than two engines for a flight more than 90 minutes (with all engines operating at cruise power) from an Adequate Airport unless the following fuel supply requirements are met:
  - (1) The airplane has enough fuel to meet the requirements of [§ 121.645(b)](/cfr/14/121.645.md?p=b);
  - (2) **The airplane has enough fuel to fly to the Adequate Airport—**
    - (i) Assuming a rapid decompression at the most critical point;
    - (ii) Assuming a descent to a safe altitude in compliance with the oxygen supply requirements of [§ 121.333](/cfr/14/121.333.md); and
    - (iii) **Considering expected wind and other weather conditions.**
  - (3) The airplane has enough fuel to hold for 15 minutes at 1500 feet above field elevation and conduct a normal approach and landing.
- (b) No person may dispatch or release for flight an ETOPS flight unless, considering wind and other weather conditions expected, it has the fuel otherwise required by this part and enough fuel to satisfy each of the following requirements:
  - (1) **Fuel to fly to an ETOPS Alternate Airport.**
    - (i) **Fuel to account for rapid decompression and engine failure.** The airplane must carry the greater of the following amounts of fuel:
      - (A) Fuel sufficient to fly to an ETOPS Alternate Airport assuming a rapid decompression at the most critical point followed by descent to a safe altitude in compliance with the oxygen supply requirements of [§ 121.333](/cfr/14/121.333.md) of this chapter;
      - (B) Fuel sufficient to fly to an ETOPS Alternate Airport (at the one-engine-inoperative cruise speed) assuming a rapid decompression and a simultaneous engine failure at the most critical point followed by descent to a safe altitude in compliance with the oxygen requirements of [§ 121.333](/cfr/14/121.333.md) of this chapter; or
      - (C) Fuel sufficient to fly to an ETOPS Alternate Airport (at the one engine inoperative cruise speed) assuming an engine failure at the most critical point followed by descent to the one engine inoperative cruise altitude.
    - (ii) **Fuel to account for errors in wind forecasting.** In calculating the amount of fuel required by [paragraph (b)(1)(i)](#b-1-i) of this section, the certificate holder must increase the actual forecast wind speed by 5% (resulting in an increase in headwind or a decrease in tailwind) to account for any potential errors in wind forecasting. If a certificate holder is not using the actual forecast wind based on a wind model accepted by the FAA, the airplane must carry additional fuel equal to 5% of the fuel required for [paragraph (b)(1)(i)](#b-1-i) of this section, as reserve fuel to allow for errors in wind data.
    - (iii) **Fuel to account for icing.** In calculating the amount of fuel required by [paragraph (b)(1)(i)](#b-1-i) of this section (after completing the wind calculation in [paragraph (b)(1)(ii)](#b-1-ii) of this section), the certificate holder must ensure that the airplane carries the greater of the following amounts of fuel in anticipation of possible icing during the diversion:
      - (A) Fuel that would be burned as a result of airframe icing during 10 percent of the time icing is forecast (including the fuel used by engine and wing anti-ice during this period).
      - (B) Fuel that would be used for engine anti-ice, and if appropriate wing anti-ice, for the entire time during which icing is forecast.
    - (iv) **Fuel to account for engine deterioration.** In calculating the amount of fuel required by [paragraph (b)(1)(i)](#b-1-i) of this section (after completing the wind calculation in [paragraph (b)(1)(ii)](#b-1-ii) of this section), the airplane also carries fuel equal to 5% of the fuel specified above, to account for deterioration in cruise fuel burn performance unless the certificate holder has a program to monitor airplane in-service deterioration to cruise fuel burn performance.
  - (2) **Fuel to account for holding, approach, and landing.** In addition to the fuel required by [paragraph (b)(1)](#b-1) of this section, the airplane must carry fuel sufficient to hold at 1500 feet above field elevation for 15 minutes upon reaching an ETOPS Alternate Airport and then conduct an instrument approach and land.
  - (3) **Fuel to account for APU use.** If an APU is a required power source, the certificate holder must account for its fuel consumption during the appropriate phases of flight.

# §121.647. Factors for computing fuel required.


Each person computing fuel required for the purposes of this subpart shall consider the following:

- (a) **Wind and other weather conditions forecast.**
- (b) **Anticipated traffic delays.**
- (c) **One instrument approach and possible missed approach at destination.**
- (d) Any other conditions that may delay landing of the aircraft.