Don’t Activate Approaches

Here’s a potentially provocative statement: Don’t activate approaches.

As I have explained in other posts (list below), with most modern GPS navigators, there’s no need explicitly to activate an approach. Activating an approach isn’t magic–that step simply makes the initial fix (called the “transition” in Garmin and other navigators) the current direct-to waypoint.

Don’t activate approaches

In many–perhaps most–cases, proceeding direct to the initial fix you choose when you load an approach is not what you–or ATC–want the navigator to do, at least right now. ATC may assign vectors to the final approach course or clear you to a different initial fix. In particular, if you activate vectors to final (VTF), the fix you need may no longer be visible and available on the moving map and flight plan page, leading to what I call the vectors-to-final scramble. But loading an approach early, with an appropriate initial fix, gives you time to review and brief the procedure–and to prepare for changes that ATC may make to your best-laid plans.

More information:

Avoiding the Vectors-to-Final Scramble

Flying Instrument Approaches without Activating the Approach

Setting a Course v. Vectors to Final

Changes to Vectors-to-Final in Garmin GTN System 6.x

New ATC Phraseology for RNAV Aircraft

A Procedure is Waypoints

When you fly an RNAV approach with a GPS navigator, the system performs a series of calculations and internal tests, such as confirming GPS signal accuracy and precision. As you proceed along feeder routes or vectors toward the final approach fix, the navigator also smoothly narrows the course width from en route to terminal to approach scale, and finally it displays the best available minimums for the approach given your system’s capabilities. But from your perspective in the cockpit, an approach–even when you use a GPS to complement a conventional approach such as an ILS–is essentially a sequence of waypoints, like other legs of a flight plan. Understanding that fact and knowing how to work with flight plans are the keys to setting up an approach and confirming that the procedure is progressing as you expect.

To help you practice using its avionics, Garmin offers free PC-based and iOS trainers (simulations) of its navigators:

On the flight plan page, if the active leg or direct-to fix is below the procedure title, the approach is active.

Instead of explicitly activating an approach, follow these steps to load and fly an approach (the same basic technique also works when flying STARS):

  • Load the procedure you want to fly.
  • For transition, choose a fix appropriate for the direction from which you’re arriving.
  • Load, but don’t activate, the approach. Review the procedure. Wait until you confirm that you’ll receive vectors to join a segment of the procedure or until ATC clears you direct to an initial fix.
  • If ATC vectors you to join a feeder route/transition or the final approach course, activate the appropriate leg of the procedure.
  • If ATC clears you to a fix, proceed direct to that fix.

This technique also keeps the fixes in the flight plan should you want to fly the approach again after flying a missed approach or if you need more time to configure the airplane or deal with a distraction.

Consider the the RNAV (GPS) Y RWY 4 at Moses Lake, WA (KMWH). If you approach KMWH from the east, choose ONPIC or MWH as the transition. If you arrive from the west, choose EDSEW, RUBEL, or ONPIC.

If ATC provides vectors to join the final approach course between ONPIC and UBGUY (the FAF), activate that leg.

But if ATC clears you to MWH, ONPIC, RUBEL, or EDSEW, you can still easily proceed direct and fly the approach beginning at that new point.

Here’s what a sequence beginning at MWH looks like in the Garmin GNS 530W simulator.

Loading the RNAV RWY 04 Y approach with MWH as the transition (initial fix).

The map view shows all the fixes and the course reversal.

The approach title appears in the flight plan, with the fixes after MWH available.

You can proceed direct to MWH to fly the full procedure. Or, to accept vectors to the final approach course, delete the hold and activate the leg between ONPIC and UBGUY.

If you arrive at KMWH from the west, EDSEW is a logical choice for the transition.

Loading EDSEW keeps other fixes in the flight plan and visible on the map.

If you are cleared and proceed direct to EDSEW, the approach is active–because the current direct-to fix is below the procedure title.

If ATC vectors you to join the final approach course outside UBGUY (the FAF), you can activate the leg to UBGUY.

Select UBGUY, press MENU, and choose Activate Leg.

Confirm that you want to activate and fly the leg ONPIC to UBGUY.

The flight plan page shows ONPIC to UBGUY is the active leg.

The active leg (magenta) on the map helps you anticipate the intercept.

Note that with UBGUY, the FAF, as the end of the active leg, the GPS annunciates LPV, another confirmation that the approach is active.

Another Example

Here’s a similar sequence using a Garmin GTN 750 to fly the RNAV (GPS) RWY 34 approach at Arlington, WA (KAWO), north of Seattle. The steps follow the basic logic and presentation used in the GNS 530W.

Here’s flight plan from KBFI to KAWO with SAVOY as an enroute fix above the procedure title. SAVOY appears again below the procedure title as an IAF.

When ATC clears you direct SAVOY, select the instance of SAVOY labeled as an IAF, below the procedure title, and choose direct-to.

Now SAVOY is the active fix, and because it’s below the procedure title, the approach is active.

If you have an electronic PFD such as the Garmin G500 TXi, the waypoint sequence appears below the HSI. Here it shows direct SAVOY (an initial fix), with YAYKU, the FAF, as the next waypoint in the sequence–another confirmation that the approach is active.

As you continue, the GTN 750 sequences to the remaining fixes in the approach toward the missed approach point. The GTN annuciates LPV, confirming the approach is active. If you go missed, the waypoints sequence through to the published missed approach hold.

3 Responses to Don’t Activate Approaches

  1. BRIAN LARKY says:

    Bruce, thanks for this outstanding discussion – it finally made sense! I worked it all simultaneously on my GTN750 iPad sim until it flowed easily. Up this weekend to practice. Keep ’em coming – they are read and they do make a difference!

    • bruceair says:

      I am glad you find the explanations useful. I am working on more discussions of techniques that help folks address common points of confusion.

  2. Pingback: An IFR Scenario for Practice in an ATD | BruceAir, LLC (bruceair.com)

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: