When should frequency changes not be issued to single-piloted helicopters?

Frequency changes should not be issued to single-piloted helicopters during taxiing, air hovering, and low-level flight primarily due to the need for the pilot to maintain full attention on flying the aircraft safely. In these situations, the pilot is often managing critical flight tasks that require concentration and attention to the aircraft's position and movements. Issuing frequency changes during these phases can create unnecessary distractions.

During taxiing, the pilot must stay aware of the surroundings to avoid obstacles and manage communications with ground control. In air hovering, precision control of the helicopter is crucial, and low-level flight presents added challenges such as avoiding terrain and navigating through airspace features. Under these conditions, altering the frequency can detract from the pilot's ability to maneuver the helicopter safely.

In contrast, during climb-out, final approach, and congested airspace, while it's still important for the pilot to be focused, there may be established procedures and protocols in place that allow for frequency changes without significantly impacting safety, as the pilot can usually anticipate these changes better and manage them more effectively.