Consider the RNAV 30 approach to C83 (Byron, CA), Plate

On a recent training flight requesting vectors for the approach, ATC pointed us to the MOVDD IF before cutting us loose (informing us that we would be getting a vector to that fix). The segment between here and the FAF is 11 degrees off from the final segment. On a GTN650 at least (and I assume other similar Garmin devices), selecting “Vectors” as the approach method gives you the FAF line with your deviation from it & sequences from the FAF. This seems not correct for flying this particular approach. The best my CFI & I could come up with was to enter the approach as being flown from the IAF (SMONE) then select “Direct to MOVDD” sometime before reaching it (such as when ATC gives the last turn), after which the GPS will sequence to the intermediate-to-final segment. But this seems non-standard. What do others do in this situation?

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    $\begingroup$ I'm not a pilot, but it seems to me "Vectors" would be the wrong approach method if you're getting vectors to an IF rather than vectors to final approach course. When vectoring to an IF we can allow up to a 90º intercept, and you follow the approach course inbound on your own; when vectoring to final approach course there is a maximum 30º intercept. $\endgroup$
    – randomhead
    May 23 at 2:52
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    $\begingroup$ Learn the difference between Activate Approach and Activate Vectors to Final. HERE and HERE are two resources to get you started. $\endgroup$
    – dawg
    May 24 at 17:47
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    $\begingroup$ Not knowing the G650 (but I do know the G550, G1000 and G3000) what you would likely do is 1) From the Flightplan Page, select Direct to: MOVDD; 2) When appropriate (when cleared for the approach) select PROC a) ACTIVATE APPROACH (that is a single button on the G1000 and G3000...) $\endgroup$
    – dawg
    May 24 at 17:51
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    $\begingroup$ Selecting Activate Vectors to Final does something different. It draws a line from the TZ straight through the FAF and beyond. The unit 1) deletes all waypoints up to the FAF and 2) sets the shortest intercept of 90º or less. THERE IS NO TERRAIN CLEARANCE PROVIDED so that intercept might be through a mountain. $\endgroup$
    – dawg
    May 24 at 17:59
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    $\begingroup$ What exactly were you cleared or instructed to do? "N12345, cleared direct MOVDD, cross MOVDD at or above 3000, cleared RNAV 30 approach", or "N12345, fly direct MOVDD, maintain at or above 3000, expect vectors to final", or something else? $\endgroup$
    – Pondlife
    May 25 at 23:29

Since most fatal accidents are during approach, it is important to maintain 100% compliance with the procedure and have a clear understanding of what your FMS will do with different modes.

There is an important Garmin / FMS distinction between:

  1. Selecting "Activate Approach" mode when navigating to a fix leading to an approach sequence, and;

  2. Navigating directly to the FAF via ATC vectors by selecting "Vectors to Final" ("VTF") mode.

If you select Vectors to Final in G1000 or G3000 (likely similar to your G650), the following things happen (from memory, I may have missed a few):

  1. The waypoints in the flight plan are bypassed (but remain inactive in the plan and available to re-navigate direct to) and the FAF is made active;

  2. Approach mode is engaged (which increases needle sensitivity);

  3. If you have a non-GPS approach loaded, the frequency for that approach is made active and the needles switch to the relevant indication (green needles for ILS for example);

  4. If you are navigating to a GPS waypoint, the FMS turns off lateral guidance and engages roll-mode (if you are in Heading mode, that mode is maintained);

  5. The HSI Bearing Needle is set to the final approach course (or outbound course for a back course approach);

  6. A graphical magenta line representing an extension of the line between the touchdown zone and the FAF is drawn on the map.

It would be unusual to use VTF (in IFR conditions) without being under some form of ATC guidance on vectors and terrain clearance - Hence 'Vectors' to Final. The use for VTF mode is usually when the pilot receives a clearance as follows:

ATC: N188L, six miles from BABPI, turn right heading 280, maintain two thousand six hundred until established on final approach course, cleared RNAV runway 30 approach Byron Airport.
Pilot: Right turn 280, two thousand six hundred until established, cleared RNAV 30 approach, 88L.

(The italicized sections are meaningful; look them up in the Pilot Controller Glossary)

At that point (assuming already at 2600), the pilot

  1. Affirms the correct approach is loaded in the FMS flight plan;
  2. Dials in 280º on the heading bug;
  3. Engages heading mode, and;
  4. selects Vectors to Final and the Garmin will then auto engage the approach from the FAF inbound. (Since this is a LPV approach, the Garmin will also intercept the vertical flight path.)

A contrary but common clearance might also be:

ATC: N188L, cleared direct MOVDD, cross MOVDD at or above three thousand, cleared RNAV runway 30 approach Byron Airport.
Pilot: Direct MOVDD, MOVDD at or above three thousand, cleared RNAV 30 approach, 88L.

In this case, there is a distinctly different FMS sequence:

  1. Affirm the correct approach is loaded in the FMS flight plan;
  2. Select MOVDD in the flight plan (this will be either an IAF or an IF);
  3. Select Direct To - Enter - Enter to make active;
  4. Select FMS mode (if not already selected and skipping the part to make sure the ship does not jump uncomfortably towards MOVDD);
  5. Engage Approach Mode;
  6. The Garmin will now auto sequence the approach including auto selecting green needles to fly an ILS or VOR if required. The Garmin will also intercept the vertical flight path if available.

You state in your question ATC pointed us to the MOVDD IF before cutting us loose (informing us that we would be getting a vector to that fix)

So what you do is:

  1. Enter Direct To MOVDD and fly that course;
  2. Select Activate Approach when you are cleared to fly that approach;
  3. If ATC gives you a vector (perhaps because ATC does not want you to go straight there) then you enter heading mode and use the bug for that vector. Reset Direct To when ATC stops vectoring you.
  4. Even if you receive a vector, you continue to have MOVDD as the active waypoint and you do not engage VTF unless you receive a clearance and a vector related to that clearance with the intent of you ending up on the final approach course near the FAF or a linear extension of the final approach course.

For illustration, consider the approach to KEGE (below, with the Vectors To Final magenta line drawn.

If you were to select VTF well outside of the IAF for this approach (and you were not under ATC POSITIVE CONTROL) there is a high risk that you would hit the 11,200 foot mountain just 7 miles from the FAF on the magenta line.

If VTF is engaged at a time when the pilot does not understand the sequence or limitations, BAD THINGS CAN HAPPEN! The FMS itself does not maintain terrain clearance for you.

enter image description here

  • $\begingroup$ Thanks for making clear the distinction between "vectors to final approach course" and "vectors to IAF/IF." OP's question, though, is what to do when the intermediate approach course they're being vectored to is not aligned with the actual final approach course to the runway. wbeard suggests dialing in a radial off a relevant fix (e.g. the 131º radial off BABPI or the 311º radial off MOVDD) and following that inbound to BABPI before actually selecting the "approach" to follow. Could you discuss that possibility in your answer? $\endgroup$
    – randomhead
    May 25 at 22:48
  • $\begingroup$ Your current answer has the same problem as OP's question: If OP does actually receive vectors to the final (or rather, intermediate) approach course outside BABPI or MOVDD, they will be vectored to join a 314º/317º/311º course—but selecting "vector to final" will generate a 300º course to join instead. $\endgroup$
    – randomhead
    May 25 at 22:52
  • $\begingroup$ @randomhead: If the expected vectors are not received to MOVVDD as expected, the pilot should clarify expectations with ATC. If the expected vectors are not received under actual IFR conditions, treat either rationally or as lost comm. It sounded actually as if this was a practice approach under VFR conditions and the controller became too busy to handle as expected (if I had to guess...) $\endgroup$
    – dawg
    May 26 at 3:20
  • $\begingroup$ @randomhead: Thanks for the edits btw. Useful! $\endgroup$
    – dawg
    May 26 at 3:21
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    $\begingroup$ @dawg - This was an IFR approach, though conditions were VMC. There was significant weather in the area though, and the approach was pretty bumpy which made it extra exciting. $\endgroup$ May 27 at 3:16

You stated ATC indicated they will give you vectors to the IF and not vectors to final (VTF). Why would you select VTF when that is not what ATC is doing? It's a rhetorical question but hopefully designed to allow you to realize that VTF is, in my opinion, the non-standard method.

I have flown lots of different GPS/FMS installations. They all have VTF feature. Some called it activate approach while other call it VTF. All of these will provide guidance to the final approach capture fix (FACF) which is typically the waypoint in front of the FAF. Some approaches don't have an intermediate fix outside the FAF and those may have a computer navigational fix (CNF) that the GPS / FMS uses to align the final approach course. All CNF waypoints are surrounded by square brackets [CFBTF] as depicted on KICT ILS 01L. You will only see the CNF waypoint if you do not select a transition on the GPS / FMS.

Others approaches, like the one you mentioned have multiple waypoints outside the FAF. In this case, you will not see any waypoints outside the FACF (in this case, MOVDD). If you were vectored to one of those you will need to select SMONE as the transition and let the FMS / GPS auto-sequence after you pass it.

  • $\begingroup$ Seems like my slightly educated guess was correct (OP selected "vectors to final" when they did not, in fact, receive vectors to final). But supposing they had actually received vectors to the 311º or 317º final approach segments, what would be the proper way of programming the GPS? $\endgroup$
    – randomhead
    May 23 at 13:22
  • $\begingroup$ On a garmin, I would would go direct to a waypoint that is along the 311 or 317 track. I would then hit the OBS button and select the 311 or 317 radial. You will see the magenta line on the screen move to align with the CDI. You can then visually see the intercept ATC is giving you. At some point (I don't remember when) you will need to deselect OBS for the approach to sequence correctly. $\endgroup$
    – wbeard52
    May 23 at 13:29
  • $\begingroup$ If ATC provided the unlikely instruction of “Fly heading xyz; vector to the intermediate segment between MOVDD and BABPI,” I guess I’d highlight BABPI in the flight plan, hit menu, and select “activate leg.” But I highly doubt that was the instruction. $\endgroup$
    – eater
    May 26 at 6:06
  • $\begingroup$ @eater, why would you doubt there could be an instruction to intercept the approach course outside of the FAF? It seems in OP's case there was not, they were vectored to the IF instead. But vectoring to join a course outside the FAF is not uncommon by any stretch of the imagination. $\endgroup$
    – randomhead
    May 27 at 14:40

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