According to DOC 4444 (ICAO), which condition warrants a wake turbulence non-radar separation minima of 3 minutes?

The condition that warrants a wake turbulence non-radar separation minima of 3 minutes is when a LIGHT aircraft is taking off behind a MEDIUM aircraft from a parallel runway. This scenario is critical due to the potential for wake turbulence created by the larger aircraft, which can extend into the takeoff path of the following LIGHT aircraft.

When a MEDIUM aircraft takes off, it generates wake turbulence that can pose a serious hazard to any LIGHT aircraft operating in close proximity, particularly during takeoff where the LIGHT aircraft is climbing and may still be heavily affected by these air currents. The requirement for a 3-minute separation helps ensure that the wake turbulence has sufficiently dispersed before the LIGHT aircraft takes to the skies.

In contrast, other scenarios might not necessitate such a time-based separation due to differences in aircraft size, flight paths, or operational environments. The established wake turbulence separation criteria are in place to mitigate risks and enhance safety during closely-timed operations, especially in the context of parallel runway operations.