Which report should be made to ATC without a specific request when not in radar contact?

When not in radar contact, a report when leaving the final approach fix inbound on final approach is essential for ATC to maintain situational awareness and ensure safety. This report informs air traffic controllers of the aircraft's progression towards the airport, which is particularly critical since the aircraft is now on its final approach. It helps ATC to monitor the flight and assist in coordinating with other air traffic, especially in busy airspace.

The necessity of this report is further emphasized in the context of approach procedures, where timely and accurate information is vital. Therefore, even without a specific request from ATC, pilots are expected to report their position as they leave the final approach fix, facilitating effective communication and management of air traffic.

In contrast, entering instrument meteorological conditions and correcting an estimated time of arrival (E.T.A.) are important but are not mandated as reports that must be made without a specific request while not in radar contact. These events typically fall under different reporting criteria and may not immediately impact ATC's ability to manage current air traffic.