When must pilots request alternate missed approach instructions?

Pilots are required to request alternate missed approach instructions before commencing the approach to ensure they have a clear understanding of what to do in case a missed approach is necessary. This request allows air traffic control (ATC) to provide specific guidance tailored to the approach and current weather conditions, ensuring the pilot is prepared for a safe go-around should the need arise.

Requesting alternate instructions before the approach also aligns with good operational practices, as it gives pilots the opportunity to review and brain-map the available options while they still have time, ensuring they are oriented and ready to execute the appropriate procedures. This proactive approach contributes to overall safety and situational awareness.

The timing of this request is crucial; doing so after already beginning the approach can lead to unnecessary confusion or delays in executing a missed approach, especially in dynamic flight environments where conditions may change rapidly.