What procedure should be followed if an airfield closure exceeds 90 days?

When an airfield closure exceeds 90 days, submitting a Flight Information Publication (FLIP) change request is the appropriate procedure to follow. This action is essential because an extended closure impacts the information that pilots and air traffic might rely on for navigation and safety. Updating the FLIP ensures that this critical data is available to all users, maintaining safe operations in the airspace surrounding the airfield.

The other options, while they might involve airfield management, do not specifically address the necessity to formally notify pilots and other relevant parties about prolonged closures through the necessary documentation and updates that the FLIP represents. Thus, fulfilling the requirement to keep flight-related data current is why this procedure is significant.