Definition
The initial approach fix (IAF) is the charted point where the initial segment of an instrument approach procedure begins. It marks the transition from the en route or arrival phase into the structured approach, and is the point from which the aircraft begins maneuvering to align with the final approach course, typically by means of a course reversal, a procedure turn, a holding pattern in lieu of procedure turn, or a feeder route to another fix.
Plain English
The starting point of an instrument approach. When the aircraft reaches this fix, it leaves the en route phase behind and begins the published steps that lead it down to the runway.
Context Anchor
Seen on instrument approach charts and in procedure turn instructions, where it tells the pilot where the approach sequence begins.
Derivation
Initial means 'first' (from Latin initialis, 'beginning'). Approach means moving toward the runway under the published procedure. Fix is a navigation term for a defined geographic point. Together: the first defined point of the approach.
Why Pilots Care
It marks the transition from enroute or feeder routing to the approach segment, ensuring correct position and altitude for safe descent and alignment.
Intuition Check
Do not read “fix” as something being repaired. In aviation navigation, a fix is a known point in the sky or on a chart. The initial approach fix is the starting point for the approach, not necessarily the point closest to the runway.
Example Sentence 1
Cleared direct to the IAF, the pilot began descending to the published altitude and prepared to fly the procedure turn.
Example Sentence 2
After receiving clearance, the pilot proceeded directly to the initial approach fix to begin the approach.