CAPTAIN SIM COMMUNITY FORUM - Glide slope dead

dt

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Glide slope dead
Jul 01^st, 2012, 9:55am

Sometimes on ILS approach glide slope deviation shows 'above G/S' constantly on approach. I could follow it to the ground and still be 'above G/S' on approach. Problem seems to be random. I took off from Heathrow (EGLL), flew to Manston (EGMH) with GPS DirectTo, activated GPS vectors to final on 28 and did ILS approach with autopilot. Glide slope was showing proper reading and autopilot followed ILS perfectly. Go around and repeat with hand flying and same result - glide slope showing proper reading. Then flew back to Heathrow with GPS DirectTo, activated GPS vectors to final 27L. This time glide slope was constantly showing 'above G/S', even though I was below or at glide slope.

i1198.photobucket.com/albums/aa457/depenthene/egllgs1.jpg
i1198.photobucket.com/albums/aa457/depenthene/egllgs2.jpg

Checked Heathrow ILS with slew and got correct glide slope.

I had same problem in various different airports too (PHNL, KORD, PANC, EFHK), but problem is not probably the airports since never had problem with other aircraft on glide slope. I can't seem to recreate problem or circumstances leading to it.

Anyone else experience anything like this?

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windplayer Senior Member Offline Posts: 528 Izhevsk, Udmurtia, Russia	Re: Glide slope dead Reply #1 - Jul 1^st, 2012, 11:23am Something new to me. But most of my day time landings with good weather i do by PAPI\VASI lights. I'll check it.
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CoolP Senior Member Offline #299 Posts: 2430	Re: Glide slope dead Reply #2 - Jul 1^st, 2012, 7:42pm dt wrote on Jul 1^st, 2012, 9:55am: Anyone else experience anything like this? Not yet. Looks like a tricky thing with that random occurrence.
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dt Newcomer Offline Posts: 13 Finland	Re: Glide slope dead Reply #3 - Jul 1^st, 2012, 8:31pm Had same problem doing ILS to EFHK 15, but glide slope became active during on final. I did switch momentarily AP to AUTO GS, but not sure it was the thing that fixed the problem. Looking more into it.
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CoolP

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Re: Glide slope dead
Reply #4 - Jul 1^st, 2012, 8:48pm

Perhaps you need to toggle the AP mode once. Lou mentioned that before. This forces a reinitialization of that system.

Read this post on the details with that internal timer while using AUTO. http://www.captainsim.org/yabb2/YaBB.pl?num=1234458523/65#65 It's related to the 727, but I guess the 707 AUTO and MAN thingy acts in the same manner.

LOU wrote on Oct 28^th, 2010, 3:50am:

Once the ILS is captured by the autopilot a timer starts in the autopilot. As the aircraft gets closer to the runway the LOC and G/S get more sensitive. Boeing designed the glide slope to begin desensitization as the plane would get closer to the runway. In the 727-100 this was based on time. (the 727-200 used the radar altimeter - much better! Did not need to use this procedure.)

So, if you are on an extended (long) final and you have intercepted the ILS at a higher altitude the G/S would need to be re-sensitized during the approach. Here is how you do this: While in AUTO G/S and on LOC and G/S, you select a non radio mode - HEADING SELECT, then select MANUAL G/S quickly by pushing down on the switch and move to MANUAL G/S. Folks, this is way too detailed for this simulator. Just don't fly too long a final and intercept at a higher altitude. You can fly a 50 mile LOC (done sometines in KLAX or KLAS) just don't select AUTO G/S until 7 or 8 miles out.

I hope this information helps. It's a bit technical, but simmers like myself enjoy the detail. I find this CS-727 to be a blast and a lot of fond memories of the old plane which was always fun to fly.

Remember this is a "game" not a multi-million dollar simulator. I think it's a great simulation and it flys pretty much like the real thing which was not CAT-II. Give it a try and don't rush the approach and it will do a good job.

Lou

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dt

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Re: Glide slope dead
Reply #5 - Jul 1^st, 2012, 9:11pm

CoolP wrote on Jul 1^st, 2012, 8:48pm:

Perhaps you need to toggle the AP mode once. Lou mentioned that before. This forces a reinitialization of that system.

Read this post on the details with that internal timer while using AUTO. http://www.captainsim.org/yabb2/YaBB.pl?num=1234458523/65#65 It's related to the 727, but I guess the 707 AUTO and MAN thingy acts in the same manner.

Thank you for the information. Have to try play with AP on approach, if I only could figure out what circumstances causes the problem to appear. Never had same problem with CS727 or 737, could be FSX problem too.

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LOU

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727,707,747,757,767=
40years of Boeings

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Re: Glide slope dead
Reply #6 - Jul 1^st, 2012, 9:47pm

Most of the time any of the planes do a good job of tracking the LOC & G/S.

I say most of the time because every so often a fruitron gets lost and all the
other fruitrons seem to get tired as well. When this happens, I do what the guy did
in the video CoolP posted in general section. Grin

Lou

Is this your instillation? Shocked

I'm just asking... Wink

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CoolP Senior Member Offline #299 Posts: 2430	Re: Glide slope dead Reply #7 - Jul 1^st, 2012, 10:10pm Yeah, looks like my last one.
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Markoz Senior Member Offline Posts: 7888 Victoria, Australia	Re: Glide slope dead Reply #8 - Jul 2^nd, 2012, 4:59am LOU wrote on Jul 1^st, 2012, 9:47pm: *Is this your instillation?* http://img801.imageshack.us/img801/6263/messq.jpg I'm just asking... Uploaded with ImageShack.us Yikes! My wife would have me "drawn and quartered" if my computer looked like that!
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BrianG

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Re: Glide slope dead
Reply #9 - Jul 2^nd, 2012, 5:43am

DT,
I used to have that problem as well. By accident I found the cause was running the AP in Nav mode when using the Doppler or GPS. If I disengage the AP to land by hand while the AP was still in NAV mode, my GS would act exactly as you described. I found the solution was to flip it from Nav Mode to LOC/VOR before you disengage the AP. Then the GS would come alive and function as it should. Auto landings worked fine. It was just failing to go from Nav to LOC/VOR before turning off the AP for a manual landing is where the problems would start

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dt

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Re: Glide slope dead
Reply #10 - Jul 2^nd, 2012, 7:15am

BrianG wrote on Jul 2^nd, 2012, 5:43am:

DT,
I used to have that problem as well. By accident I found the cause was running the AP in Nav mode when using the Doppler or GPS. If I disengage the AP to land by hand while the AP was still in NAV mode, my GS would act exactly as you described. I found the solution was to flip it from Nav Mode to LOC/VOR before you disengage the AP. Then the GS would come alive and function as it should. Auto landings worked fine. It was just failing to go from Nav to LOC/VOR before turning off the AP for a manual landing is where the problems would start

That was exactly the problem and like you said solution was to go to LOC/VOR before disengaging AP. Thank you.

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BrianG Full Member Offline Posts: 156	Re: Glide slope dead Reply #11 - Jul 2^nd, 2012, 3:18pm Glad it works for you now. I struggled with that one for a long. Enjoy.
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windplayer Senior Member Offline Posts: 528 Izhevsk, Udmurtia, Russia	Re: Glide slope dead Reply #12 - Jul 2^nd, 2012, 11:21pm Guys! i just made some circles in 707. Another question appeared. Looks like F\D in NAV\LOC, GS AUTO\MAN turns off GS indicator just like in upper posts. I never used F\D really, and today i wanted to dig it, and thats what i found. Is that supposed to be like that? (I flew by hand)
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LOU Senior Member Offline 727,707,747,757,767= 40years of Boeings Posts: 1276 Central PA, USA	Re: Glide slope dead Reply #13 - Jul 3^rd, 2012, 2:56am That is not the way it is supposed to work. I never use the F/D in the 707 or the 727 because there is a bug in there somewhere. Lou
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CoolP Senior Member Offline #299 Posts: 2430	Re: Glide slope dead Reply #14 - Jul 3^rd, 2012, 8:07am So far, I was happy with the FD on the 707 when on the ILS. In another thread, I took some screenshots and the GS indicator and FD indication worked fine. www.captainsim.org/yabb2/YaBB.pl?num=1315732558/17#17
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