What condition requires maximum caution when avoiding wake turbulence on landing?

The scenario that requires maximum caution when avoiding wake turbulence on landing is when a light, quartering tailwind is present. In this condition, the behavior of the wake turbulence is notably unpredictable due to the wind vectors at play.

When landing with a light, quartering tailwind, the wake turbulence generated by a preceding aircraft may drift towards the runway where the following aircraft is landing. This is exacerbated by the wind, which can cause the turbulence to linger longer and spread further than it might under other wind conditions. The light tailwind affects the sink rate and the ground speed during approach, making it crucial for pilots to be aware of their position relative to any preceding aircraft.

In contrast, during a heavy, direct headwind, strong crosswind, or calm winds, the conditions may allow for better dissipation of wake turbulence or more predictable behavior, thereby reducing the likelihood of encounter during landing. Therefore, vigilance is particularly critical in a scenario with a light, quartering tailwind to ensure a safe landing free from wake turbulence impacts.