What are the four segments of an Instrument Approach Procedure (IAP)?

The four segments of an Instrument Approach Procedure (IAP) are indeed initial, intermediate, final, and missed.

The initial segment is where the aircraft transitions from the en route phase of flight to the start of the approach, establishing the aircraft's position in relation to the airport. It often involves navigation to a designated fix or waypoints.

The intermediate segment connects the initial segment to the final approach and typically involves altitude restrictions and heading instructions that prepare the aircraft for a stable approach to landing.

The final segment provides the critical path to the runway, where the aircraft is aligned and descending towards the runway threshold, typically guided by various types of approach aids such as an Instrument Landing System (ILS) or a visual approach slope indicator (VASI).

The missed approach segment is an essential part of the procedure that outlines what actions the pilot should take if the landing cannot be completed due to inadequate visual references or other reasons. This segment ensures that there is a safe and structured method for transitioning back to the en route phase if the landing cannot be executed.

In summary, this sequence ensures a structured and systematic approach to landing, which is crucial for maintaining safety in instrument flight operations.