Which factor is NOT relevant for aircraft weight and balance considerations?

When considering aircraft weight and balance, the relevant factors include anything that directly affects the load the aircraft is carrying at any given time, which impacts its performance, handling, and safety. Fuel load, passenger weight, and cargo load are all critical elements as they contribute to the total weight of the aircraft and influence its center of gravity.

Fuel load is relevant as it fluctuates with consumption during flight, thus affecting weight and balance dynamically. Passenger weight is also important because it varies with the number and size of individuals aboard, directly impacting the aircraft’s overall weight and balance calculations. Similarly, cargo load affects both the total weight and the distribution of weight in the aircraft.

In contrast, flight duration does not directly affect the aircraft's weight and balance at the outset. While longer flights might lead to more fuel consumption and therefore a change in weight over time, the initial calculation for takeoff does not consider how long the flight will last. Instead, the focus is on the actual weight being carried at the time of measurement. Therefore, flight duration is not a relevant factor for initial weight and balance considerations.