segments of an instrument approach procedure

An instrument approach procedure may have as many as five separate segments, depending on how the approach procedure is structured. The approach segments begin and end at designated fixes. However, under some circumstances certain segments may begin at specified points where no fixes are available (e.g., the final approach segment of a precision approach may originate at the point of intersection of the designated intermediate flight altitude with the normal glide path). These segments are the:

i. Arrival segment. The route followed from the en route phase of the flight to the initial approach fix. It usually starts at an en route fix and ends at the initial approach fix, generally the first navigational facility associated with the procedure. Also known as a feeder route or a terminal route.

ii. Initial approach. That segment of an instrument approach procedure between the initial approach fix and the intermediate approach fix or, where applicable, the final approach fix or point.

iii. Intermediate approach. That segment between either the intermediate fix and the final approach fix or point, or between the end of a reversal, racetrack, or dead-reckoning track procedure and the final approach fix or point, as appropriate.

iv. Final approach. The segment in which the alignment and descent for landing are accomplished.

v. Missed approach procedure. The procedure to be followed if the approach cannot be continued for any reason.