What is the recommended procedure for departures when volcanic ash is present?

In the context of departures when volcanic ash is present, the recommended procedure involves using a rolling takeoff. This technique is beneficial because it allows the aircraft to achieve lift-off speed more gradually while maintaining a continuous rollout, which minimizes the risk of ingesting significant amounts of volcanic ash during the takeoff phase.

A rolling takeoff generally means that the aircraft builds speed continuously from the start of the runway rather than using a full stop-and-go approach. This method is particularly critical in conditions with volcanic ash, as the ash can cause engine damage and significantly reduce performance. By rolling and gradually accelerating, pilots can ensure a smoother transition into the air while being cautious of the hazardous conditions associated with volcanic ash.

Other takeoff options, such as short or medium takeoffs, might not provide the same level of gradual acceleration and could risk a higher engine workload from sudden increases in thrust. A standard takeoff may also involve a more abrupt transition which could lead to more ash ingestion during the critical phase of increased thrust. Thus, the rolling takeoff is the safest and most effective technique in these challenging circumstances.