Menu Sign In Contact FAQ
Banner
Welcome to our forums

Flight Director

The last “wtf” moment I had when I let it fly an ILS but for whatever reason the GNS430W did not auto slew the pointer and like always in these situations, I tried fixing the AP setup instead of taking over control and putting the aircraft on course…

Explaining the theory was one thing flying it is another job….
Even with my relatively simple set up one can get easily some mode confusion (when relatively new with the system). E.g. on the SN3500 one should not forget to push on the course selector and preferably de-select the map modes (to see the cross bars decently) when getting established on the Loc or you may not be able to get the A/P coupled (guess how I know). The wtf…..was solved by reverting on NAV2 and some hand flying and reading the manual once again…I here you guys saying of course ….how can you forget…well on the King KCS it is immediately visible of course. If I would have had a descent simulator I could have trained all this stuff into much more detail then trying to figure it all out during some training flight..The wtf moments are not that good when the weather is IMC and your in the approach…..One of the reasons I like my bird so much you cant revert easily back to complete basics and hand flying…

EBST

In my plane I have a “checklist for ILS” which contains all the steps e.g. set DCT to airport, set GPS to OBS, set LOC bearing, set NAV/GPS switch to NAV, press APR when approaching magenta line. Leave out one step and it can be a whole load of fun Press APR too soon and you can pick up a false localiser. It is the only checklist I use when airborne.

I concur discovered I need the same: a customized for my bird Approach checklist (GPS RNAV, ILS etc..) … On another training flight I was practicing some ILS stuff we where playing with the A/P but skipped the nav mode and went immediately-from HDG to Approach mode to early in this case, not yet on the FAF, birdy trying to catch the glide of course (read pitch up)….The correct sequencing selection on a EHSI, A/P mode programmer on some more modern A/P systems is crucial. The Approach mode is the moment of truth

EBST

An ILS checklist ditty that I have found handy with the GNS430/530 is “Morse, Source, Course”. Morse is to identify the localizer. You are forced to select the correct ILS frequency and make it to the active Nav frequency in order to identify the Morse code. Source requires you to verify that the Source for the HSI/CDI has VLOC and not GPS selected. Course reminds you to set the OBS Course pointer or verify that it has been properly auto slewed.

KUZA, United States

“Morse, Source, Course”

I like that one

CDI has VLOC and not GPS selected

The 500$ button, but it has become more like 1000$ nowadays

Last Edited by Vref at 19 Mar 12:41
EBST

Achim,
yes, really i also don’t rely on the “auto slew” feature of the 430 anymore. I did 3 approaches with exactly the same ground track – one time it switched, two times it didn’t. But that’s really a “feature” of the 430, not the A/P. My friend and IFR checker who flies 320s for LH and Biz Jets says that they had the same problem in some Biz Jet (forgot the type) – the auto slew would never work.

Now I try to keep things simple. I use HDG+NAV, switch to VLOC early and just wait until the A/P intercepts the Loc. That has many advantages especially since with the DFC90 there is no difference between the NAV and GPSS modes. That’s a bizarre thing that they put the GPSS button on it, but the reason (according to Avidyne!) was that they had to keep the UI as similar to the S-TEC55X it replaces as possible.

The DFC90s brother DFC100 has no GPSS button, and it is essentially the same autopilot. I could not believe that so i reseacrhed the topic and Avidyne confimed that the A/P will behave the same in NAV and GPSS mode. I am not sure about GPSS approaches, probably those have to be flown with the GPSS button.

Last Edited by Flyer59 at 19 Mar 13:05

one time it switched, two times it didn’t

There has to be a reason for that, however. I am sure Garmin didn’t put in a random number generator

If it was me, I would find out otherwise one day it might bite me, when I am busy in the cockpit and need the automation to work.

This sort of thing is one reason why I am not rushing to sink another 20k+ into the latest (and buggy as hell, relatively speaking) avionics eye candy. The 1990s stuff I have fully works, and it is only the job creators in the regulatory establishment who keep inventing new ways to make it obsolete “on paper”.

Administrator
Shoreham EGKA, United Kingdom

It will not bite me, because I now switched OFF that automation. If you do the switch manually you are much safer anyway, becasue you will check that the Final course is set in the EHSI.

Most pilots with that equipment will tell you that the “auto slew” feature is unreliable. And really if I fly the same ground track three times and it doesn’t always work – there still might be some reason i don’t understand, but it’s a design flaw anyway because the behaviour cannot be that obscure. All Cirrus pilots I talked to said the same: Do the switch from GPS to VLOC manually and you are safe.

The GNS430W is otherwise a very reliable box and I have never discovered any flaws, and so is the Entegra glass cockpit and the DFC90 A/P. I bet it’s more reliable than any mechanical HSI etc.

Well, a mechanical HSI, or an EHSI, doesn’t do the “GPS/NAV” switch automatically anyway.

The HSI/EHSI is nothing to do with this functionality.

It happens only with integrated GPS+LOC(+GS) boxes, and the LOC detection will presumably be vulnerable to false LOC signals, and/or there is a database-coded “hint” to the box to look for the LOC at point X which may be intercept angle dependent.

Administrator
Shoreham EGKA, United Kingdom

I have found both my GNS W boxes to be rock solid during the approach sequence. I do not recall having any issue with auto slew, providing I follow the correct buttonology a la morse and source and then verify the course.

In my set up the Aspen provides GPSS, but this is not enabled in approach mode, which is a direct connection between the GNS box and the AP.
E

eal
Lovin' it
VTCY VTCC VTBD

I have just had the KI256 replaced with my shelf spare, and now the FD indicates +10 deg in level flight… Previously it was indicating +5deg. The RHS AI has an FD also and that shows the right pitch – about 3 deg.

Not really worth fixing. I don’t fly with the FD. I wonder if anyone here uses theirs? The above is quite an old thread.

Administrator
Shoreham EGKA, United Kingdom
Sign in to add your message

Back to Top