Courses - Instrument Approaches

Traditional Courses

An aircraft that has been cleared to a holding fix and subsequently “cleared…approach,” normally does not receive new routing. Even though clearance for the approach may have been issued prior to the aircraft reaching the holding fix, ATC would expect the pilot to proceed via the holding fix that was the last assigned route, and the feeder route associated with that fix, if a feeder route is published on the approach chart, to the IAF to commence the approach. When cleared for the approach, the published off-airway (feeder) routes that lead from the en route structure to the IAF are part of the approach clearance.

If a feeder route to an IAF begins at a fix located along the route of flight prior to reaching the holding fix, and clearance for an approach is issued, a pilot should commence the approach via the published feeder route. For example, the aircraft would not be expected to overfly the feeder route and return to it. The pilot is expected to commence the approach in a similar manner at the IAF, if the IAF for the procedure is located along the route of flight to the holding fix.

If a route of flight directly to the IAF is desired, it should be so stated by the controller with phraseology to include the words “direct,” “proceed direct,” or a similar phrase that the pilot can interpret without question. When a pilot is uncertain of the clearance, ATC should be queried immediately as to what route of flight is preferred.

The name of an instrument approach, as published, is used to identify the approach, even if a component of the approach aid is inoperative or unreliable. The controller will use the name of the approach as published, but must advise the aircraft at the time an approach clearance is issued that the inoperative or unreliable approach aid component is unusable. (Example: “Cleared ILS RWY 4, glideslope unusable.”)

Area Navigation Courses

RNAV (GPS) approach procedures introduce their own tracking issues because they are flown using an onboard navigation database. They may be flown as coupled approaches or flown manually. In either case, navigation system coding is based on procedure design, including waypoint (WP) sequencing for an approach and missed approach. The procedure design indicates whether the WP is a fly-over (FO) or fly-by (FB), and provides appropriate guidance for each. A FB WP requires the use of turn anticipation to avoid overshooting the next flight segment. A FO WP precludes any turn until the WP is over flown and is followed by either an intercept maneuver of the next flight segment or direct flight to the next WP.

Approach waypoints, except for the missed approach waypoint (MAWP) and the missed approach holding waypoint (MAHWP), are normally FB WPs. Notice that in the plan view in Figure, there are four FB WPs, but only the circled WP symbol at PRINO is a FO WP. If flying manually to a selected RNAV WP, pilots should anticipate the turn at a FB WP to ensure a smooth transition and avoid overshooting the next flight segment. Alternatively, for a FO WP, no turn is accomplished until the aircraft passes the WP.

Courses - Instrument Approaches
Fly-by and fly-over waypoints

There are circumstances when a WP may be coded into the database as both a FB WP and a FO WP, depending on how the WPs are sequenced during the approach procedure. For example, a WP that serves as an IAF may be coded as a FB WP for the approach and as a FO WP when it also serves as the MAWP for the missed approach procedure (MAP). This is just one reason why instrument approaches should be loaded in their entirety from the FMS and not manually built or modified.

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