Definition
A charted point that marks the beginning of the initial segment of an instrument approach procedure. From the IAF, the aircraft transitions from the en route or arrival phase into the structured approach, following published courses, altitudes, and any required course-reversal or procedure track toward the intermediate fix.
Plain English
The point on an approach chart where the instrument approach actually begins. When you reach this point, you stop flying en route and start flying the published approach.
Context Anchor
Seen on the plan view of an instrument approach chart, usually near the outer part of the drawn approach path.
Derivation
Initial' comes from the Latin 'initialis' meaning 'of the beginning.' 'Fix' in aviation means a defined geographic point that can be identified by navigation. So an initial approach fix is literally the point where the approach begins.
Why Pilots Care
It shows the pilot exactly where to begin following the published altitudes, courses, and fixes that lead to the runway.
Intuition Check
Do not read “fix” as something being repaired. Here, a fix is a specific position in the air. “Initial” does not mean the start of the flight; it means the start of the approach procedure.
Example Sentence 1
The controller cleared us direct to the IAF and then to fly the full approach.
Example Sentence 2
ATC cleared the flight direct to the IAF to start the approach.