What condition is required for conducting 'timed approaches from a holding fix' if only one missed approach procedure is available?

Conducting timed approaches from a holding fix when only one missed approach procedure is available requires the weather to meet the highest published circling minimums for the instrument approach procedure (IAP). This is because, during a timed approach, a pilot must be prepared to execute a missed approach if necessary, and ensuring that the visibility and ceiling meet the circling minimums provides a safer margin for transitioning from the final approach to the missed approach.

If the visibility does not meet these requirements, the pilot may not be able to proceed safely to the runway or execute the missed approach safely, which is particularly critical in scenarios where only one missed approach procedure is available. Hence, adhering to the highest circling minimums ensures that both conditions for a successful approach and a missed approach are satisfied.

The other options do not ensure adequate safety margins during the approach phase, emphasizing why the focus on circling minimums is crucial in this scenario.