What key feature distinguishes unmanned aerial vehicles (UAVs) from traditional aircraft?

The key feature that distinguishes unmanned aerial vehicles (UAVs) from traditional aircraft is the absence of a human pilot. This characteristic fundamentally alters how UAVs are operated, allowing for remote control or autonomous operation without the direct presence of a pilot on board. This design enables UAVs to perform tasks in environments that may be too dangerous for manned flights, such as disaster response or military reconnaissance missions.

The absence of a human pilot also leads to variations in design and functionality compared to manned aircraft. For instance, UAVs can be built to be smaller and lighter, optimized for specific missions without the need to accommodate a cockpit or life-support systems. This capability allows for innovations in operational range and flexibility, as UAVs can operate in challenging settings for extended periods.

In contrast, while speed, payload capacity, and altitude range are important features in evaluating both UAVs and traditional aircraft, they do not serve as defining characteristics that set UAVs apart. The definitive aspect remains the lack of a pilot on board, making UAVs unique in their operation and application.