Resolved Erroneous glideslope indications

[Quickmarch 488]

C-130

Anyone flying the Captain Sim C-130? If so, let me know if you're experiencing the same issues with the glideslope, described below.

I've a few issues with it that I'm wondering about:

One is covered elsewhere in MH and has to do with flying the C-130 in AH where the electrics go out immediately after takeoff. The solution to this problem has been to accept the default panel conditions and start the engines with Cntl-E. This problem doesn't affect AI pilots.

The latest one that is tripping me up a little bit is the glide slope indications.

GS capture seems to go well, the needle coming alive where it's expected - then all visuals go wrong. If I fly the needle the VASI (or more modern equivalents) is always indicating that I'm way too high. If I bring the aircraft up to match the needle I break out over the opposite end of the runway (it's that bad).

My first few approaches resulted in go-arounds when there was nothing in sight at DH. Took me a second to realise there was nothing there because it was behind me.

At first I thought it might be a glitch with the airport I was heading into, in that case CYYJ. CYYJ has a localizer problem in FSX where the localizer is off to the right of the runway (27), but there is a fix available and it is installed. So I was blaming the airport programming, initially. That is; until I did a few circuits and visual approaches in CAVU WX conditions. This detected the VASIS versus GS needle discrepancy. Also the "Don't Sink!" and "Pull Up!" verbal cockpit warnings which can be very distracting when you know you're way above the GS. These warnings are tied to the needle position so, naturally, start nagging you if the GS is turned on during a normal visual approach.

Still convinced this was an airport programming problem, I flew off to CYVR for some circuit work on 26R. Same problem.

I'm convinced there is an issue with the aircraft programming and have no idea how to go about repairing this. It will likely be buried somewhere in the gauge settings.

I might play about with replacing the stock ADI with one out of the stock FSX aircraft group (I have gauge programming software, but not a lot of expertise). I have already done this as I have GS in my Aerosoft Beavers, not a stock item. This was a pretty simple gauge swap and might solve the problem that I'm having with the C-130.

Comments or suggestions welcome.

[allardjd 1,853]

March,

 

For a temporary gauge I'd suggest just adding one in a pop-up window instead of trying to replace an existing gauge or make it fit cosmetically into the panel. 

 

I've only flown the FS9 CS C-130 and don't recall ever having any problems like that.

 

Just a shot in the dark, totally unlikely - back course selected?  Seems like the indications would be reversed but can't remember how the dials work when flying away from the airport (or toward it from the front-course end) with the BC button pressed.

 

John

[Quickmarch 488]

Thanks for the quick reply, JA,

That would certainly cover the problem, however, there is no BC switch that I can recall anywhere in the Nav system. I cannot find any reference to back course in the manual, either. Both CYVR (26L) and CYYJ have non-precision approaches as I recall.

The Capt Sim C-130 uses a flight director system that pretty much covers your exposed parts. The runway hdg is dialled into the HSI and the computer drives the ADI using this info and the frequency selected in the Nav1 radio.

I'll look into this one if I get a chance to load FSX this evening.

[Quickmarch 488]

OK JA,

 

I loaded the aircraft and sure enough - there's no back course switch to be found anywhere in the cockpit. Does your FS9 version have one? I'm going to stick with my original comments, above, that the computer, using the HSI and Nav1 radio info drives the needles on the ADI. I'm going to try two approaches to 09/27 at CYYJ, one from the west and one from the east. The two share the approach frequency so that will tell me if it is trying to use the 09 GS info on the 27 approach.

 

ADE shows an ILS-GS on 108.7mHz (IKH) for rwy09 - 106deg and an ILS-GS on 108.7 (IYJ) for rwy 27 - 286deg. Both runways are VASI equipped so the discrepancy will be obvious if I fly a visual with the approach dialed in to the Nav1 radio.

[allardjd 1,853]

I've run into that business before with both ends of a runway using the same ILS frequency and one end is squirrely. I found it in some beta testing and had a long, one-way conversation with the developer in which I did some extensive testing. Can't remember most of the details but I have the notes and will dig them out. The vendor wasn't too interested and I pretty much got a cease and desist message, even though their stuff was causing the problem.

 

Is there any chance that the airports are add-on AFCAD provided as part of another package and not stock FSX airports?

 

John

 

[allardjd 1,853]

March,

I've found my notes and they contain copious data. This was from a beta test of a commercial add-on program that included many AFCADs to enhance airports. Those were not the primary element of the program but were included to augment it.

 

At some, but not all of those airports that used the same ILS frequency at both ends of a runway, the ILS indications were weird-squared. They worked OK if approaching from one end but essentially gave back course data from the primary end if approaching from the other end. Wind/WX changes forcing traffic to use the other end didn't correct the problem.

 

I only focused on three airports, EGLL, EGKK and KSEA. All three use the same ILS frequency at both ends but KSEA behaved normally and did not exhibit the problem - the other two did.

 

I determined that if I turned off the scenery layer that was installed by the program I was testing, the problem went away for EGLL and EGKK. KSEA worked properly whether that scenery layer was active or not. My conclusion was that something in the AFCADs were causing the problem, but I chose not to follow that particular dog up that alley.

 

I am hesitant to name the program or vendor here, but have the relevant beta reports in the form of the original e-mails that I sent to the vendor reporting the issue and some follow-up testing on it. If you want them, I'll forward them to you.

 

It's hard to say for sure but it sounds as if you may be having the same problem I found. If you have a scenery layer that includes any add-on airports for those where you're experiencing this issue, try unchecking that layer in the Scenery Library and trying again.

 

John

[Quickmarch 488]

Thanks aha in, JA,

I was so knackered after yesterday's museum marathon that I fell asleep in the evening and did not get to test the C-130 issue. I did load ADE and check the "stock" CYYJ. ADE showed the erroneous ILS for Rwy27 with the localiser offset to the right of the runway. I do have an aftermarket fix installed in my scenery files for CYYJ - the fix deals with the offset. I should check CYVR as well as there is likely to be an aftermarket upgrade to that airport in my scenery stuff as well.

I'm laying the blame on the Capt Sim C-130 for the issue because I use both airports all the time flying in both FSX Free Flight and AirHauler. I don't recall having issues (except for the CYYJ offset localiser) with either airport when flying other aircraft. But I cannot recall whether or not I've flown ILS approaches to minimums in complex aircraft. I do know that the offset localiser was picked up by flying a PMDG 737 into CYYJ and breaking out well to the right of the runway. I've recently flown the Q400 into CYYJ on the Rwy27 ILS (not to minimums) and do not recall any erroneous instrument displays.

I think I should start by flying the approaches in the default C-172 and see how the GS reacts in that aircraft. You have given me some serious food for thought and a bit of flying time to try to resolve the problem.

[allardjd 1,853]

I think I should start by flying the approaches in the default C-172 and see how the GS reacts in that aircraft.

 

 

I concur - see if the problem follows the aircraft or the airports. 

 

KSEA has a similar ILS setup and worked OK for me during the beta testing.

 

John

[Quickmarch 488]

OK

 

The problem is likely in the C-130. I just flew both approaches to CYYJ, 09 and 27. Both were spot on. The default Cessna chirped on the 1500ft marks.

 

Next, I'm set up to start the same approaches in the C-130. I saved the C-172 when inbound to the IAF at the correct altitude and heading, so barring any unforseen glitches during the aircraft switch over, I should be back in half an hour or so with the report on the C-130. If I get a chance, I might even take some screenshots.

[Quickmarch 488]

I'm back!

 

Definitely the C-130. 

 

So you'll know what I'm referring to, here's a clip of the RW approach plate for runway 09 at CYYJ, Victoria, BC. I'll be coming in from the left at the BRANY intersection. A little later I'll remark on the "high ground" - that's it just after the intersection, spot height 3027ft. I'm dropping down from 4700ft at 500fpm towards the 11DME point where I should be at about 3600ft and right on the GS.

 

 

 

The GS came up at 4500 ft. and showed a solid 1-1/2 dots on the needle.

 

Unfortunately, I didn't get a shot of this as I was too busy cleaning out my shorts. What actually happened was that the Gamepad didn't hook up right away (remember I'm taking a saved Cessna flight and inserting the C-130) and I had to pull the plug on it then plug it back in before I hit the high ground. So I got a brief glimpse of the needle where it should be before I realised I wasn't able to correct the sink.

 

Anyway once the excitement died down, I climbed back into the cockpit and took a look. The needle was already below the centre hash mark and nothing I could do would bring it back up. The following screenshot was taken after I climbed way above the GS. Note the altitude is 5100 feet and the GS needle on the left side of the ADI is almost buried below the scale.

 

 

I figured this approach was toast, but what the heck, I was already at VFE so I cut the power and started feeding in flap. The next shot is the approach angle you need in a C-130 when approximately 10nm from the threshold at 5000 feet. Sure are dirty engines, aren't they? No carbon credits for March today.

 

 

So here we are at 1200 feet coming down like a rock - about 2800 fpm, power going back on before we park it in the ocean. Note the solid white (too high) indication from the VASIS to the left of the runway.

 

 

Things were going much better than expected. Man, can this baby sink if it has to. So I popped out of the cockpit for a quick angel's eye view of the proceedings and captured the aircraft a few nanoseconds before touchdown. I'm flaring at this point, but there's still quite a bit of sink. Note the VASIS still stuck on white - 1500 foot markers just showing above the wing. My, this airplane throws a big shadow.

 

 

I grabbed the opportunity to use my newfound prowess with the Gamepad second stick and did a quick 90 degree swing out to port to get the touchdown. Smoke!

 

 

That's it folks.

 

What do we know? We know that for some strange reason the Captain Sim C-130 glide slope indicator, once heading south cannot be dissuaded. There was some talk in the manual about the computer loosing it's lock and the need to get back under the glide slope to reconnect, but I've tried that several times now and it doesn't work.

 

I'm going to look into JA's suggestion to put a separate window up with a Cessna 172 VOR/ILS instrument in it for now. If anyone can come up with a solution to this problem, I'd sure like to see it.

[allardjd 1,853]

Have you had a chance to look at the CS forums, assuming there is such a thing?  If it's that bad, others are struggling with it too.  I don't have this AC loaded in FS9 any more since changing computers but have flown many ILSs with it and it was always well behaved as long as you intercepted the GS from below.  It's an ancient and archaic Smiths AP, but it does what it's advertise to do in FS9 - you're right - no back course capability with that one.

 

John

[Quickmarch 488]

I'm not sure that's a good suggestion, John.

 

I joined their forum only to read that the forum is for "information only" and that any problems should be directed to their technical people. I did research as much as possible - that's where I found the reference to the disappearing electrics (not a unique problem at all). It sure doesn't sound like they are going to welcome any comments/criticism. It's hard to know because it feels like a very foreign sort of site. Here's a quote from one of their administrators in answer to a fairly simple question that was posted on their forum:

Quote

Please note, this forum is not for technical support. For technical support please check-in to Your Profile , click Product name link and use Customer Support link.

Un Quote

 

I like your suggestion to simply add an instrument with GS capability in a pop-up window. I'm pretty sure I can manage that. If I can't I know where there's a real friendly forum that can.

 

The possibility always remains that the problem is one of my own making. I need to spend a lot more time pushing buttons in that cockpit.

[allardjd 1,853]

It is a button-rich cockpit.

 

John

[Kasper 14]

I do have the Herc in FSX. I can not recall that I have encountered this problem but I will make a testflight tomorrow and report back.

[Quickmarch 488]

Thanks for you interest, Kasper. I'd appreciate your input.

[Kasper 14]

March see the screenshots. I do not have the same problem.

My guess is that the Herc's systems did not initialize correctly being switched in mid-air from a cessna. But that really is just guessing

 

 

[Quickmarch 488]

Thanks Kasper,

 

It does not seem to matter whether or not I start the flight from the ground or from loading a saved flight. The major issue is that it the Joystick (in my travelling mode, a Gamepad) must be unplugged on loading, then plugged in a few seconds after the flight is active. This can be exiting as the total time from connect to having usable control inputs is close to one minute.

 

Playing around with it early this morning yielded the following:

 

There is a switch in the VC that does not work - it just happens to be the one I need to activate the course computer. It is the one on the AP mode select panel that selects "Manual" or "Normal". I have been trying to use it in the VC. I used the switch in the "Normal" condition this morning from the 2D cockpit "AP" popup. This worked for manual approach using the GS needle. I also tried the same approach using the "Glide" setting on the AP and that works well too, allowing the AP to track the GS.

 

This seems to be the answer to the problem.

[allardjd 1,853]

So, this one is solved?

 

John

[Quickmarch 488]

Seems to be, John,

However, it will take me a few days to repeat the process. I'm now in Nice. Cool train ride down here from Paris at incredible speeds compared to our North American passenger trains. Almost like flying.

Do you know how to flag this thread with "solved"? The iPad interface is a bit challenged (or maybe it's the nut behind the wheel).

[allardjd 1,853]

Do you know how to flag this thread with "solved"?

 

 

Done!  Happy the problem seems to be behind you.  That's a great AC to fly and it would be a shame to have it so hampered by a bug.

 

John