IFR fuel requirements vary according to aircraft operations. with most falling under Part 91, 121, or 135 FAR Regulations

Let’s take a look at each.

Fuel Requirements for IFR Flights

Part 91 IFR Fuel Requirements

Many people reading this article will be most interested in Part 191 fuel requirements. They apply to general aviation and cover private flying.

So let’s cover these first.

According to FAR 91.167:

You are not able to fly in IFR conditions unless your aircraft carries enough fuel (taking into account weather reports, forecasts, and conditions) to:

  • Land at your intended airport
  • Fly from that airport to the alternate airport; and
  • Fly after that for 45 minutes at normal cruise fuel consumption or, for helicopters, fly for 30 minutes

However, you may disregard having enough fuel to fly from an alternate airport if:

  • You are issued a standard instrument approach procedure or a special instrument approach procedure for the first airport of intended landing;

AND

  • Either alone or through a combination of weather reports or forecasts, it is indicated that:

For aircraft other than helicopters:

  • Visibility will be at least 3 statute miles at a ceiling of at least 2,000 feet above the airport elevation – for at least 1 hour before and 1 hour after your estimated time of arrival

For helicopters:

  • At your estimated time of arrival and for 1 hour after, visibility will be at least 2 statute miles at a ceiling of at least 1,000 feet above the airport elevation, or at least 400 feet above the lowest applicable approach minima. Whichever is higher takes precedent

Part 121 IFR Fuel Requirements

Part 121 applies to scheduled air carriers, like the majors and regionals.

According to FAR 121.167:

You are not able to dispatch or take off an airplane unless it has enough fuel:

  • To fly to your destination airport
  • To fly from that airport to the alternate airport
  • Fly after that for 45 minutes at normal cruise fuel consumption, or for 30 minutes if you are flying a non-transport category airplane that is also authorized to fly under VFR

Part 135 IFR Fuel Requirements

Part 135 applies to commuter and on-demand operations, like corporate, and charter flights.

According to FAR 135.223:

You are not able to fly in IFR conditions unless your aircraft carries enough fuel (taking into account weather reports, forecasts, and conditions) to:

  • Land at your intended airport
  • Fly from that airport to the alternate airport; and
  • Fly after that for 45 minutes at normal cruise fuel consumption or, for helicopters, fly for 30 minutes

However, you may disregard having enough fuel to fly from an alternate airport if:

  • You are issued a standard instrument approach procedure or a special instrument approach procedure for the first airport of intended landing;

AND

For at least one hour before and after the estimated time of arrival, either alone or through a combination of weather reports or forecasts, it is indicated that:

  • The ceiling will be at least 1,500 feet above the lowest circling approach minimum descent altitude

OR

  • The ceiling will be at least 1,500 feet above the lowest published minimum or 2,000 feet above the airport elevation if a circling instrument approach is not authorized

IN ADDITION TO

  • Depending on which is greater, visibility at that airport is forecast to be at least three miles, or two miles more than the lowest applicable visibility minimums, for the instrument approach procedure to be used at the destination airport