What type of aircraft is defined as operating without direct human intervention?

The definition of an aircraft that operates without direct human intervention refers specifically to unmanned aircraft (UA). These are designed to fly without a pilot on board and can include various levels of automation. In this context, unmanned aircraft encompass those that are remotely piloted as well as those that operate autonomously.

Autonomous aircraft, while they may operate without direct human intervention, typically still fall under the broader category of unmanned aircraft. Manned aircraft, on the other hand, require a human pilot on board, which does not align with the definition given. Remote-controlled aircraft involve direct human control but through radio signals, which means they are not operating without human intervention.

Thus, the correct answer accurately captures the essence of aircraft that can function independently of a pilot, making it fundamental to understanding the classification of aircraft within the context of the FAA regulations.