When must ZAE forward the destination airport information to JAN APCH?

The correct answer is that ZAE must forward the destination airport information to JAN APCH when the flight is other than JAN. This situation arises from procedural requirements in air traffic management, particularly in non-radar environments where communication and information sharing between different air traffic control facilities is critical for ensuring safe and efficient airspace operations.

When an aircraft is on an approach to a destination that is not JAN, passing this information helps JAN APCH to better manage the air traffic in their area, anticipate incoming flights, and maintain safe separation between aircraft. The forwarders, in this case, ensure that all relevant information is relayed promptly to maintain situational awareness.

The other choices do not encompass the necessary criteria for forwarding destination airport information adequately. For instance, just communicating when the aircraft is at cruising altitude or once they are in the airspace does not fully address the requirement for transferring information regarding the destination airport, specifically when it is not JAN. Therefore, the emphasis on the nature of the destination is critical in understanding the correct protocol for information forwarding in air traffic management.