What defines standard separation for aircraft after they have crossed the runway end?

Standard separation for aircraft after they have crossed the runway end is defined as "landing and clear of the runway." This means that the aircraft must have completed its landing roll and is no longer on the runway surface before the next aircraft is allowed to take off or land on that runway. This practice ensures safety by minimizing the risk of collision during the critical phases of landing and takeoff.

While visual confirmation from the tower and distance from the taxiway are important components of air traffic management, they do not solely define when standard separation is achieved. Visual confirmation may help in assessing the situation on the ground, but the critical factor for separation is that the aircraft be fully cleared from the runway, as this establishes a clear path for subsequent operations. Thus, the key focus is on the aircraft's status of being "landed and clear of the runway," making it the defining criterion for standard separation in this context.