What is a common IFR fuel reserve requirement and its purpose?

• A. About 10 minutes of reserve fuel to cover short delays.
• B. About 60 minutes of reserve fuel for long diversions.
• C. About 30 minutes of reserve fuel at planned consumption to cover delays or diversions.
• D. No reserve required for IFR.

Answer: (C)

In IFR flight planning, you carry a safety margin of fuel beyond what you need to reach your destination (and any required alternate). That extra fuel is the reserve. A common standard is 30 minutes of reserve fuel, calculated at your planned cruise consumption rate. This means you estimate how much fuel you would burn per hour during cruise, take half an hour’s worth as a buffer, and add it to the fuel needed to arrive at the destination (and to reach an alternate if one is required). The purpose is to absorb delays, holding, or an unexpected diversion without running out of fuel, ensuring you can land safely with a usable fuel margin. The other options don’t match typical IFR practice: 10 minutes is too little for a meaningful buffer, 60 minutes is more than the common reserve, and saying no reserve is required would compromise safety.