Which statement correctly defines endurance in aviation performance terms?

• A. Endurance equals TAS multiplied by distance.
• B. Endurance = usable fuel divided by the consumption rate (hours).
• C. Endurance equals the total fuel capacity.
• D. Endurance is the same as range.

Answer: (B)

Endurance is the amount of time an aircraft can stay aloft with the usable fuel on board, given the engine’s fuel consumption rate. It is found by dividing usable fuel by the fuel flow (hours). This means you’re measuring how long the airplane can fly before running out of usable fuel, not how far it can go. For example, with a certain usable fuel amount and a known burn rate, you can calculate how many hours you can stay airborne.

This is different from range, which is a distance you can cover during that time at a given cruise speed. It’s also not the total fuel capacity, since not all onboard fuel is necessarily usable in flight, and reserves and other factors reduce the usable quantity.