What condition must be met to ascertain that you have an adequate interval behind another aircraft?

To determine that there is an adequate interval behind another aircraft, it is essential that the aircraft ahead has turned at least 90 degrees and is either abeam or behind your wingtip. This condition is critical because it ensures that the aircraft you are following has safely moved out of your immediate flight path, reducing the risk of collision and allowing for safe maneuvering.

When an aircraft turns 90 degrees, it significantly alters its flight path relative to your position. Being abeam means that the aircraft is directly to the side of you, while being behind your wingtip means it is trailing after you—both positions indicate that there is a sufficient lateral or rear distance between the two aircraft, creating a safe operational space.

While having a clear line of sight and being equipped with a traffic collision avoidance system can enhance situational awareness and safety, they do not definitively ensure an adequate interval. Similarly, maintaining speed relative to the aircraft ahead does not directly correlate to the spacing required for safe operations. The critical factor is the relative positioning of the aircraft, highlighted by the specific conditions of turning and placement as mentioned.