Radius of action, or combat radius in military terms, refers to the maximum distance a ship, aircraft, or vehicle can travel away from its base along a given course with normal load and return without refueling, allowing for all safety and operating factors. This definition applies as well to military conditions.
For a given aircraft, its radius of action varies according to whether or not it carries external drop tanks, the level (altitude) of its roadmap, and the amount of weight (ordnance in a military context) it is carrying:
In military aviation, the combat radius of an aircraft is often given with its mission profile (without in-air refueling). For example:
The radius of action of an aircraft is always smaller than its maximum range, the furthest distance the aircraft can fly with maximum payload and without refueling, or ferry range, the furthest distance the aircraft can fly with drop tanks, no load or ordnance and without refueling. The rule of thumb is that the radius of action is one-third the distance an aircraft can fly in a straight line on a full load of fuel. In military aviation, this assumes a trip out and back, plus one-third of fuel for combat operations.