IFR / What should I have done?

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haykinson
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IFR / What should I have done?

Post by haykinson »

The other day the sky above me got cloudy and I looked at my logbook and said to myself, Hmm, what a good day to get an approach in for currency. I still have two months left on my IFR currency, but a) an extra approach would make that three months, and b) it’s always good to train and get experience in high ceiling actual.

I filed from my airport back to my airport. For those who know KSMO, I filed my route as SADDE DARTS and put my approach request into remarks, and then picked up my clearance over the phone as the tower was already closed. After takeoff I contacted ATC, and they vectored me a bit. To reduce workload I had entered the following on the G1000 as the flight plan: KSMO SADDE DARTS KSMO, then selected my obstacle departure (as cleared), and loaded the approach back into the airport.

Here’s where I had something unexpected to me happen. I had enabled my autopilot after takeoff, and after a few heading vectors I was told to proceed direct SMO VOR (and then to depart that on a particular heading). Since that was not in my flight plan, I had inserted SMO at the current position in the flight plan window, hit Direct To, and switched to Nav mode on the AP. The aircraft proceeded towards the waypoint. And then suddenly started turning. I switched back to heading mode immediately and tapped FPL and saw the magenta arrow pointing to SMO. Tapped NAV again and once more started turning. I was a fraction of a mile from the waypoint now, and was in VMC at the time, so I hand flew the little bit on the original heading and then left the waypoint on the assigned heading. All continued fine, though I was left scratching my head as to what I did wrong.

As I’m sure all of you have probably guessed, the issue was that I had inserted the direct-to SMO before the pre-programmed SADDE, and the flight director (and thus autopilot) were treating the SMO as a fly-by waypoint and were initiating an earlyish turn towards SADDE. I could have avoided that by deleting SADDE, though that would probably just sequence the next waypoint and still initiated some sort of a turn. Or, I guess I could have switched to VOR mode and navigated direct that way. Or maybe I could have gone to OBS mode, which would suspend future waypoints.

Of these, I don’t feel that deleting the rest of the flight plan sounds like the right move. In my approach practice environment that’s not a huge problem (would have taken me seconds to get things plugged back in) but on a longer XC route that sounds more troublesome. I’m totally fine with not using the autopilot (and practice without it when with a safety pilot) but the issue here affected the flight director as much as the autopilot, and exposed an expectation mismatch on my end.

Am I missing any best practices here?
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Chris
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Re: IFR / What should I have done?

Post by Chris »

I've been bitten by the fly-by waypoint behavior a couple of times. I don't know if there's a better way, but I've learned to just peek at the MFD to see when it's going to turn early and switch into HDG mode on the present heading if I don't want to cut the corner. Since you were going to be on a vector leaving SMO anyway, that sounds like less work than setting up the VOR and switching the CDI.

P.S. Nice use of ASCII codes in the LLC name that N880BM is registered under.
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Re: IFR / What should I have done?

Post by Boatguy »

Was the instruction you were to follow upon departing the SMO VOR, a compass heading or a radial?

If it was a radial, then you could have switched the CDI to VOR, punched the Course button and the FD/AP would have gone direct SMO. Close or over SMO you could spin the course knob to the radial you were given and it would have intercepted the radial.

If it was a heading, then the same procedure, but with the HDG button, and a twist of the HDG knob at SMO, would have put you on course.

Either method would have kept the plane under control of the FD/AP.

But I don't know how to enter either of the above into the flight plan. SIDs and missed procedures frequently contain legs which are headings or radials, but the procedures have been translated those into GPS coordinates and routes so I stay in GPS on the CDI. A good question and something to look into.
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Re: IFR / What should I have done?

Post by haykinson »

Chris wrote: Mon Jan 25, 2021 3:28 am I've been bitten by the fly-by waypoint behavior a couple of times. I don't know if there's a better way, but I've learned to just peek at the MFD to see when it's going to turn early and switch into HDG mode on the present heading if I don't want to cut the corner. Since you were going to be on a vector leaving SMO anyway, that sounds like less work than setting up the VOR and switching the CDI.
Great point. I was still on the engine page since I was still climbing and making sure my temps were under control. I guess a glance at the mini map on the PFD would have given me the same info.
P.S. Nice use of ASCII codes in the LLC name that N880BM is registered under.
Heh, thanks. I kick myself for not using mixed case values, but 🤷‍♂️
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haykinson
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Re: IFR / What should I have done?

Post by haykinson »

Boatguy wrote: Mon Jan 25, 2021 5:06 am Was the instruction you were to follow upon departing the SMO VOR, a compass heading or a radial?
Funny enough, I don’t remember. I thought it was a radial and behaved as such during the flight. But then I went back to listen to the LiveATC recordings of the flight and it was unfortunately cut off when it was recorded so I can’t confirm.
If it was a radial, then you could have switched the CDI to VOR, punched the Course button and the FD/AP would have gone direct SMO. Close or over SMO you could spin the course knob to the radial you were given and it would have intercepted the radial.
In retrospect that would probably have been the easiest. I did have the VOR tuned up, too. Just didn’t think of it in time. But these “direct to VOR” directions are just fine to fly on green needles, even if we don’t use them as much otherwise.
But I don't know how to enter either of the above into the flight plan. SIDs and missed procedures frequently contain legs which are headings or radials, but the procedures have been translated those into GPS coordinates and routes so I stay in GPS on the CDI. A good question and something to look into.
As far as I know, we can’t. I wonder if there is way to export a flight plan with these features, edit it, and reimport back in... though I can’t even find the import instructions in the G1000 guide so maybe that functionality is now gone?
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Re: IFR / What should I have done?

Post by haykinson »

haykinson wrote: Mon Jan 25, 2021 6:34 am As far as I know, we can’t. I wonder if there is way to export a flight plan with these features, edit it, and reimport back in... though I can’t even find the import instructions in the G1000 guide so maybe that functionality is now gone?
I got curious, and tried this. Exported a KSMO -> KSMO flight plan with a departure and approach procedure, and the resulting .fpl file has just one waypoint (KSMO) and nothing else. Since as far as I know these radial / non-waypoint directions only appear on procedures, I am guessing we can't export, import, or enter them.
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Re: IFR / What should I have done?

Post by waynemcc999 »

Chris wrote: Mon Jan 25, 2021 3:28 am I've been bitten by the fly-by waypoint behavior a couple of times. I don't know if there's a better way, but I've learned to just peek at the MFD to see when it's going to turn early and switch into HDG mode on the present heading if I don't want to cut the corner. Since you were going to be on a vector leaving SMO anyway, that sounds like less work than setting up the VOR and switching the CDI.
I'm with Chris on this. Keep things simple... stay on magenta needles and toggle to HDG. Seems switching OBS or green needles just adds more steps and chance for error.

Similar thing happens northbound on SoCal TEC routes (e.g. HERMO LAX VTU)... ATC gives "Direct LAX, depart LAX heading 310" (then later, direct VTU). My SOP is magenta NAV toward LAX, several miles out toggle HDG (to avoid the fly-by toward VTU), then once over LAX, twist to 310. The key, as I expect we all know, is to habitually keep the Heading bug synced.

Ilya, thanks for the fun scenario.
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Re: IFR / What should I have done?

Post by chili4way »

For pilots who are flying G1000 NXI aircraft, it's possible to make a waypoint in your flight plan explicitly a "fly-over" waypoint. Highlight the waypoint, press MENU, and scroll down to find the option.

I did not see the same capability in the Legacy G1000 PC trainer (GDU V13).

Make-Flyover.jpg
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Re: IFR / What should I have done?

Post by Boatguy »

Was ATC instructing it to be a fly-by or fly-over? When I load a flight plan / clearance I'm pretty sure they are all treated as fly-by. The GFC700 usually anticipates the turn and rounds it out as a fly-by. I've never given it too much thought. So what Ilya experienced was what I consider normal behavior.

Why do we think his instruction from ATC should have been interpreted as a fly-over?
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Re: IFR / What should I have done?

Post by waynemcc999 »

Russ, Ilya's original post at the top of this thread included:

"I was told to proceed direct SMO VOR (and then to depart that on a particular heading)"
... this to me is a fly-over, i.e. go to SMO (all the way), THEN depart on a given heading (very much like my SoCal TEC route instruction).

If instead he had been given "direct SMO then DARTS" (i.e. a Course SMO DARTS), I would interpret that as a fly-by at SMO.
[more accurately, it'd be a new clearance "cleared KSMO, direct SMO DARTS direct"... but that'd be a super crazy clearance because SMO DARTS KSMO is basically two nearly overlapping straight paths].

Maybe I'm missing something on your question? (BTW, these are fun conversations)
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