What is a "Loss of Separation" in air traffic control?

A "Loss of Separation" in air traffic control refers specifically to the occurrence when two aircraft come too close together, creating a potential collision hazard. Maintaining safe separations between aircraft is a fundamental aspect of air traffic control and ensures safety in the busy airspace system. When aircraft are horizontally or vertically separated by insufficient distances as stipulated by regulations, it indicates that a loss of separation has occurred, prompting necessary actions from air traffic controllers to resolve the situation and ensure safety.

The concept of separation is crucial in preventing mid-air collisions, and effective air traffic management relies heavily on maintaining these prescribed distances. Other options, while related to aviation safety, do not directly define the specific term "Loss of Separation." For example, exceeding budgeted fuel, leaving designated airspace, or losing power, all relate to operational concerns but do not specifically denote the proximity or safety aspect highlighted by the term in question.