Factors for computing fuel required

When calculating how much fuel to load for a Part 121 flight, you must account for several factors beyond just the basic flight time. The regulation requires considering forecast winds and weather conditions, expected traffic delays (like holding patterns or ground stops), fuel for one instrument approach plus a possible missed approach at your destination, and any other circumstances that might delay landing.

This means you can't simply calculate fuel for a direct flight in perfect conditions. You must build in realistic margins for the actual operating environment. For example, if ATC routinely assigns holding near your destination airport, or if afternoon thunderstorms typically cause arrival delays, these factors must be included in your fuel planning. The goal is ensuring the aircraft has sufficient fuel for the flight as it will actually unfold, not just as it appears on paper in ideal conditions.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*