Setting a Course v. Vectors to Final

I am not a fan of the vectors to final (VTF) option when loading instrument approaches in GPS navigators like the Garmin GNS and GTN series avionics.

As a general rule, avoid the vectors (vectors-to-final) option

Even with recent improvements to how the Garmin GTN series boxes handle VTF, it’s usually best to choose an initial fix (IF) or initial approach fix (IAF) based on the direction from which you’re arriving in the terminal environment, and then, depending on your clearance from ATC, activate a leg of the procedure or proceed direct to an IF or IAF. See the example at KMWH below.

Choosing a transition (IF) when loading an approach.

For more information about VTF, see Avoiding the Vectors-to-Final Scramble, Changes to Vectors-to-Final in Garmin GTN System 6.x, and Flying Instrument Approaches without Activating the Approach.

Occasionally, however, you may encounter an approach such as the ILS or LOC RWY 14 at Boeing Field (KBFI) (chart below).

Video of the approach described in this discussion

Knowing how to use a handy technique that straddles the line between the VTF and setting a specific course (a variation on OBS mode) can help you smoothly join the final approach course. Bear with me for a somewhat convoluted explanation.

For more information about setting a specific course to a fix and the OBS feature, search for Direct To and OBS in the pilot guide for the avionics you use.

ILS or LOC RWY 14R at KBFI

The plan view for this approach shows two key fixes along the localizer: ISOGE and TOGAE.

Plan view

TOGAE is step-down fix with a crossing restriction and a GS intercept altitude at 1600 (the beginning of the final approach segment when you fly the full ILS with glideslope). TOGAE also serves as the FAF when you fly the LOC-only version of the procedure.

In theory, Seattle Approach could vector you to join the localizer a few miles outside TOGAE (within the approach gate; see the Instrument Procedures Handbook and the P/C Glossary).

APPROACH GATE− An imaginary point used within ATC as a basis for vectoring aircraft to the final approach course. The gate will be established along the final approach course 1 mile from the final approach fix on the side away from the airport and will be no closer than 5 miles from the landing threshold.

Definition of approach gate in the P/C Glossary

The approach also chart shows ISOGE, a fix 9 nm from the ruwnay, as an IF/IAF. (You will never fly the depicted hold/course reversal anchored at ISOGE.)

And ISOGE appears in the list of transitions when you load this approach in a GPS navigator such as a Garmin GTN 750.

If you choose either Vectors or ISOGE, the fix appears in the flight plan.

If you activate VTF for this approach, the GTN draws an extended centerline from TOGAE (the FAF) out along in the localizer course. You loose ISOGE as a reference.

VTF leaves ISOGE in the flight plan, but all distance and ETE information references TOGAE.

If you activate the approach with ISOGE as the transition, the navigator draws a magenta line from your present position to ISOGE, and if you hand-fly that course or put the autopilot in NAV mode, you will head directly to that fix.

But Seattle Approach always issues a series of vectors to sequence you into the flow of traffic for KBFI and to avoid conflicts (wake turbulence and otherwise) with airliners aiming for nearby KSEA. Regardless of the direction from which you’re arriving, ATC places you on the localizer at least a few miles outside of ISOGE.

In other words, you don’t want to go direct to ISOGE, and it’s helpful to have a reference to the localizer course as ATC vectors you into the flow.

For example, I recently flew the ILS from the area near Arlington, WA (KAWO) northeast of Seattle (video here).

Radar vectors KAWO-KBFI to the ILS or LOC RWY 14R

This typical routing from the northeast involves a long vector on a southwest heading to intercept the localizer. Even if you have the navaid tuned, you may not be able to identify it and confirm its appearance on the CDI until you are almost on top of the course. If ATC is busy or if you’re flying a fast airplane, it’s easy to blow through the localizer or be tempted to make an aggressive turn to capture it when you get the final vector from ATC.

Here’s the “trick” to help you fly a smooth intercept. It involves setting a specific course direct to a fix–in other words, it’s similar to using OBS mode:

  • If you’re using the autopilot, make sure you’re in HDG mode to follow vectors from ATC.
  • Because you’re flying vectors to join the localizer, confirm that you’re showing “green needles” on the HSI or CDI used to fly the ILS. You don’t need GPS guidance from this point on.
  • Load the approach with ISOGE as the transition (i.e., as the first fix in the procedure).
  • Confirm the list of fixes in the flight plan.
  • Select ISOGE and choose direct-to.
  • In the direct-to window, enter the course inbound to ISOGE along the localizer–135 degrees.
  • On the map, you’ll see a magenta line extending to ISOGE along the course 135 degrees–in effect, an extension of the localizer.

Here’s how that sequence looks using a GTN 750:

ISOGE selected as the transition (initial fix). ISOGE is the current direct-to fix–the approach is activated.
The GTN 750 shows guidance direct to ISOGE. But ATC is vectoring you to join the final approach course at a point outside ISOGE.

To draw an extension of the localizer from ISOGE, select ISOGE again, choose Direct-To, and enter the course 135.

Setting a specific course to ISOGE.
The GTN draws a course of 135 to ISOGE, in effect, an extension of the localizer.

Now you can monitor your progress toward the final approach course and prepare for the turn onto the localizer, even if you’re not currently receiving the signal or showing a flyable localizer CDI.

Joining the localizer.

As you join the localizer and then pass ISOGE, the GTN sequences to the next fix in the approach, TOGAE. If you used OBS mode to set a course to ISOGE, the GTN would suspend waypoint sequencing past ISOGE, but setting a direct-to course preserves that feature.

On the ILS approaching TOGAE.

Two Practice Approaches

During training for the instrument rating, we fly most approaches to published minimums. But in real-world IFR flying, the weather is usually well above the visibility (which actually controls) and ceiling required to complete an approach and land.

I recently flew a couple of approaches in VMC (visual meteorological conditions), albeit with light rain reducing visibility. I couldn’t log the approaches for currency, but they were still good opportunities to practice IFR procedures, use the avionics in the A36, and keep my head in the IFR game.

The following videos also show what the runway environment looks like as you approach the decision altitude (DA), first on an RNAV (GPS) approach with LPV minimums, then an ILS.

An ILS at Night

Clear skies recently offered an opportunity to log a little night flying time and to practice an ILS at Boeing Field (KBFI). I can’t log the approach for IFR currency (I wasn’t under the hood and didn’t have a safety pilot), but it’s still good practice to fly approaches in VMC when possible to reinforce IFR procedures.

Videos: A Couple of Instrument Approaches

I took my A36 Bonanza out for some instrument practice. Here are a couple of longish videos, with ATC, that show the RNAV (GPS) RWY 20 approach at Bremerton National (KPWT) and the ILS RWY 14R at Boeing Field (KBFI).

The aircraft is equipped with a Garmin G500 PFD/MFD and GTN 750 WAAS navigator. I use ForeFlight on an iPad Mini 5 for flight planning, charts, ADS-B weather (FIS-B) and traffic (TIS-B). A good source of information about using tablets in the cockpit is iPad Pilot News.

You can find the videos on my YouTube channel, BruceAirFlying, or watch them via the direct links below.

An ILS that Requires GPS

You can still fly IFR in the U.S. without an IFR-approved GNSS (i.e., GPS), but being “slant G” (/G in the soon-to-be obsolete FAA domestic flight plan format) increasingly offers advantages, even if you fly only conventional procedures based on ground navaids. And sometimes an IFR-approved GNSS is required to fly even an ILS.

Another example is the ILS or LOC RWY 28R at Billings, MT (KBIL)

Consider the ILS Z OR LOC Z RWY 16R approach at Reno/Tahoe International Airport (KRNO). This procedure is not an Authorization Required approach–RNP doesn’t appear in the title, and you won’t find that restrictive note on the chart.

For more information about RNP procedures, see RNP Procedures and Typical Part 91 Pilots. To learn about new required equipment notes on FAA charts, see New Equipment Required Notes.

KRNO-ILSorLOCZRwy16R

But the equipment required notes for this ILS approach include “RNAV-1 GPS required.”

KRNO-ILSorLOCZRwy16R-notes
A review of the plan view and missed approach track show why GPS is necessary to fly this procedure.

KRNO-ILSorLOCZRwy16R-Plan

First, you need GPS to fly transitions from most of initial fixes, which are RNAV waypoints marked by a star symbol.

RNAV-Waypoint-Symbol

Only LIBGE, directly north of the runway, is a non-RNAV IAF.

For example, HOBOA, KLOCK, BELBE, and WINRZ are all RNAV waypoints that serve as IAFs or IFs. Now, NORCAL Approach might provide vectors to the final approach course, but if you want to fly this procedure you should be prepared for a clearance direct to one of those fixes (see Avoiding the Vectors-to-Final Scramble).

Note also that entire missed approach track requires use of GNSS.

Two of the transitions are of special note. The “arcs” that begin at ZONBI and SLABS are radius-to-fix (RF) legs that are part of the transitions that begin at HOBOA and KLOCK. Each of those fixes is distinguished by the notes “RNP-1 GPS REQD” and “RF REQD.”

The first note means that your GPS must meet the RNP 1 standard, which is used for terminal procedures such as SIDs and STARs, the initial phases of approaches, and missed-approach segments. (For more information about RNP, see RNP Procedures and Typical Part 91 Pilots.)

Until recently, RF legs were included only in Authorization Required (AR) procedures. But as I explained in Garmin GTN Avionics and RF Legs, certain RF legs are now available if you have an appropriate GNSS navigator, updated system software, an electronic HSI, and other equipment. Some limitations on flying such RFs also apply, as described in that earlier post.

Suppose that you choose the less intimidating ILS X or LOC X RWY 16R to the same runway. A review of the notes and the plan view shows that even this conventional-looking ILS also requires RNAV 1 GPS, both to fly the transition from WINRZ and the missed approach track.

KRNO-ILSorLOCXRwy16R.jpg