Joining RNAV Approaches at a fix or waypoint Prepared by John D. Collins CFI/CFII

Background With traditional ground based procedures, pilots are accustomed to joining the approach either by flying the full procedure from an airway via a feeder route or more commonly via radar vectors to the final approach course. Once the controller informs the pilot of the approach procedure to expect, the pilot can determine everything they need to know for the approach. To setup for a ground based procedure, the pilot tunes and identifies a NAVAID frequency and sets the desired final approach course on their course deviation indicator.

RNAV navigation is from a point to a point. It involves random routes via Direct-to navigation. All points are named and must be retrieved from the database. For an approach, the entire procedure must be retrieved from a database as a sequence of waypoints. To select the procedure involves programming the GPS/FMS and then transitioning to the appropriate fix when cleared.

To Program the GPS/FMS requires that the pilot know in advance 1) which approach is to be expected and 2) how the approach is to be joined. A typical RNAV “T Style” approach will have 5 or more points at which the approach may be joined (all IAF’s and feeder routes). Modern GPS/FMS also provides support for joining an approach via vectors to final (this is often a 6 th option and is the default choice of the GPS/FMS)

Vectors to Final on the typical GPS only displays two waypoints: the FAF and the MAP with a course line extending out from the FAF along the extended final approach course. Once vectors to final is chosen on the GPS, any clearance to a fix requires a reprogramming of the approach.

Joining an approach at an IF that is not also an IAF When an approach has one or more IAF(s), only the IAF(s) and the first fix of feeder routes are provided as choices by the GPS to commence an approach, an IF (or a step down fix) is not provided as a choice to commence an approach at. This requires the pilot to understand this and select an IAF from the available choices, load the approach, scan thru the resulting sequence and select the IF, then perform a Direct-to the IF.

Note 3: Aircraft being vectored to the intermediate fix in FIG 5−9−5 must meet all the provisions described in subpara 4−8−1b4.

U Section (b) 4. States: Established on a heading or course that will intercept the intermediate segment at the intermediate fix, when an initial approach fix is published, provided the following conditions are met: (a) The instrument approach procedure is a GPS or RNAV approach. (b) Radar monitoring is provided to the Intermediate Fix. (c) The aircraft has filed an Advanced RNAV equipment suffix. (d) The pilot is advised to expect clearance direct to the Intermediate Fix at least 5 miles from the fix. (e) The aircraft is assigned an altitude to maintain until the Intermediate Fix. (f) The aircraft is on a course that will intercept the intermediate segment at an angle not greater than 90 degrees and is at an altitude that will permit normal descent from the Intermediate Fix to the Final Approach Fix.

Summary If you plan on having the aircraft joining the approach at a waypoint, let the pilot know what to expect as soon as possible. Avoid using phraseology that includes “Vectors to final or Vectors for the approach” unless you intend to provide heading vectors to intercept the final approach course.

Use phraseology such as: “Vectors for the approach, Expect direct LEEMO” or “Expect to join the approach at LEEMO”