How do you determine if there is enough fuel to reach an alternate plus holding IFR?

• A. Add reserves and pretend it's enough.
• B. Compare fuel on board to maximum tank capacity.
• C. Only consider fuel for the outbound leg.
• D. Calculate required endurance to reach the alternate plus expected holding time, then ensure total fuel on board exceeds that requirement plus reserves.

Answer: (D)

In IFR fuel planning the key is to ensure you have enough endurance to reach an alternate and then hold there if needed, plus a safety reserve. So you start by figuring the time required to fly to the chosen alternate, add the expected holding time once you arrive, and use your fuel burn rate to convert that total time into fuel quantity. Then you add the prescribed reserve fuel, which covers unexpected delays or deviations. Only when the total fuel on board exceeds this calculated requirement do you have a safe margin to complete the flight.

This approach avoids assuming you can rely on the tank’s capacity to cover the trip, and it accounts for the fact you may need to divert and hold. It also covers the scenario where you’d otherwise only consider the outbound leg; the plan must include fuel to reach the alternate and to hold there if necessary, not just the initial leg.