What does altitude refer to in the context of aviation?

Altitude in aviation specifically refers to the height of an aircraft above sea level. This measurement is crucial for flight operations, as it helps pilots determine their position in the sky relative to the ground. Understanding altitude is essential for maintaining safe separation between aircraft, managing air traffic, and ensuring compliance with regulations regarding minimum and maximum flight levels.

Maintaining specific altitudes can also affect aircraft performance, fuel efficiency, and navigation. For example, knowing the altitude allows pilots to adjust their flight path to avoid terrain and obstacles, manage airspace where traffic might be congested, and follow the standard operating procedures established for different phases of flight.

In contrast to altitude, the other options relate to different aspects of aviation: speed refers to how fast the aircraft is traveling, weight concerns the mass of the aircraft affecting its lift and performance, and the distance from the runway pertains to the aircraft's position in relation to the takeoff or landing runway, which is important during flight maneuvers, but does not define altitude itself.