How is "flight altitude" defined in UAS operations?

In UAS operations, "flight altitude" is defined as the height of the unmanned aircraft above either sea level or ground level. This definition is crucial for understanding various aspects of airspace management, compliance with regulations, and safe operation of drones within proximity to people and structures.

Measuring flight altitude relative to sea level or the ground level ensures that operators can accurately assess their drone's position in relation to other aircraft and the terrain. This is especially important for maintaining safe distances from obstacles, other air traffic, and meeting the legal requirements that govern airspace use. Using such definitions allows operators to communicate effectively about altitude concerning safety protocols, navigational aids, and regulatory compliance.

The other options do not provide an accurate or complete understanding of flight altitude. While the distance a drone can reach might relate to its maximum performance capabilities, it does not specifically define flight altitude. Similarly, defining flight altitude merely as a starting height for takeoff or as maximum distance from the pilot is not comprehensive and does not capture the essential concept that incorporates either sea or ground level for measuring altitude.