investigating Andersen 06L ILS - Localizer but no Glideslope

[Nealius]

Using the F-15C to idiot-proof the freqs. Winds 055 6~7kts. 06L ILS "works" in that I can hear the morse code on the full-fidelity modules, and I get localizer needles, but the glideslope needle doesn't appear to work; it's pegged at the bottom of the ADI . Possibly connected to the flipped lead-in lights that's already known, or maybe a separate issue. Could be an F-15 issue, but I don't recall if I got glideslope or not in the Viper. Not sure, but puts a damper on low-vis recoveries. 

 

 

 

 

Edited July 8, 2021 by Nealius

[Recoil16]

Unable to reproduce, I'm getting glideslope in both the F-15C as well as in the A-10C. Can you attach a short track showing the issue?

[Nealius]

I can reproduce, but only on 1+ hour missions. Should I send one, or will that be too long?

 

In short missions it mostly works, however I found two problems even when it does work:

 

1. The glideslope is way too high, putting my touchdown point at the very end of the touchdown zone, giving 2000~3000ft less room for braking. 

2. At DME6.9 2,200ft MSL I should intercept the glideslope (per Jeppesen charts). In DCS glideslope interception isn't until around DME4. 

 

I've attached a short track showing these two issues. Should I open a separate thread for these?

ILS HIGH.trk

[Recoil16]

8 hours ago, Nealius said:

I can reproduce, but only on 1+ hour missions. Should I send one, or will that be too long?

Yeah an hour is somewhat long. I've noticed after a couple more tries that in the F-15 if you don't intercept the glideslope from below in a certain way, it acts kinda wonky. This seems to be isolated to the F-15 though, so not sure if it's really a Marianas issue.

 

8 hours ago, Nealius said:

1. The glideslope is way too high, putting my touchdown point at the very end of the touchdown zone, giving 2000~3000ft less room for braking.

When I fly the GS below minimums all the way to the runway (which shouldn't be done in the first place), it puts me right about behind the thousand footer (about 1000-1500ft from the threshold), which is at least to me looking as if it is working as intended.

 

8 hours ago, Nealius said:

2. At DME6.9 2,200ft MSL I should intercept the glideslope (per Jeppesen charts). In DCS glideslope interception isn't until around DME4.

Note that the 6.9 DME (in USAF charts 7 DME) is in reference to the UAM TACAN, not the ILS, since Andersen does not have ILS/DME. The F-15C doesn't care though, it always references ILS/DME even though it may not exist. In my A-10 I get near-perfect GS interception at 7 DME/2200 ft:

[Nealius]

27 minutes ago, Recoil16 said:

Yeah an hour is somewhat long. I've noticed after a couple more tries that in the F-15 if you don't intercept the glideslope from below in a certain way, it acts kinda wonky. This seems to be isolated to the F-15 though, so not sure if it's really a Marianas issue.

 

That must be what's going on. I'll have two flights in a row where the glideslope is pegged at the bottom of the ADI all the way down, then I'll have a flight where it appears to work normally, then I'll have two flights where the glideslope tells me to aim at the end of the TD zone or even mid-field. It seems to work most reliably if I line up from >10nm out. If I try to line up within 10nm it seems to get weird. 

[Zoddom]

I have a similar issue in the M-2000C.

 

My virtual runway is being shown like 1 mile in the sky above the actual runway, plus the localiser leads me away from the airfield in a random direction. Pretty annoying.

Not sure if its only Andersen or also the other ILS approaches, gotta try those.

[Nealius]

3 hours ago, Zoddom said:

I have a similar issue in the M-2000C.

 

My virtual runway is being shown like 1 mile in the sky above the actual runway, plus the localiser leads me away from the airfield in a random direction. Pretty annoying.

Not sure if its only Andersen or also the other ILS approaches, gotta try those.

 

Do you have QFE set? Using QNH can cause issues with the synthetic runway, but the localiser should still work.

[Zoddom]

vor 13 Stunden schrieb Nealius:

 

Do you have QFE set? Using QNH can cause issues with the synthetic runway, but the localiser should still work.

I dont even know how to do that lol, Ill try.

 

UPDATE:

 

Okay fair enough, I just did it for the first time EVER and I made the smoothest landing Ive ever done. However instantly afterwards I tried it again without setting the QFE and it worked almost just as well. But yesterday the virtual runway showed like 1km above and its the same mission, except yesterday I landed after an hour. Maybe its a bug with the mission time? I have disabled INS drift .

Edited July 10, 2021 by Zoddom

[Recoil16]

3 hours ago, Zoddom said:

I dont even know how to do that lol, Ill try.

 

UPDATE:

 

Okay fair enough, I just did it for the first time EVER and I made the smoothest landing Ive ever done. However instantly afterwards I tried it again without setting the QFE and it worked almost just as well. But yesterday the virtual runway showed like 1km above and its the same mission, except yesterday I landed after an hour. Maybe its a bug with the mission time? I have disabled INS drift .

 

This one sounds like a different issue to me than the one this thread is about. If you think it is related to the map, open another thread for it here in the MI subforum, otherwise if you think it's an M2K issue, open a thread in the M2K subforum. Either way, a track showing the issue would probably be helpful.

[Zoddom]

vor 45 Minuten schrieb Recoil16:

This one sounds like a different issue to me than the one this thread is about. If you think it is related to the map, open another thread for it here in the MI subforum, otherwise if you think it's an M2K issue, open a thread in the M2K subforum. Either way, a track showing the issue would probably be helpful.

Alright I keep an eye out if it happens again and save the track.

Any idea how I can make the conversion of inHG to mbar easier in the M2000?

[NineLine]

On 7/9/2021 at 7:06 AM, Recoil16 said:

Yeah an hour is somewhat long. I've noticed after a couple more tries that in the F-15 if you don't intercept the glideslope from below in a certain way, it acts kinda wonky. This seems to be isolated to the F-15 though, so not sure if it's really a Marianas issue.

Hey @Recoil16thanks for looking into this, can you do a detailed report on the Tester forums on this please and thank you so we can see if it needs to be reported? Sounds similar to other issues that seem to heavily degrade over time in game.

[Recoil16]

32 minutes ago, NineLine said:

Hey @Recoil16thanks for looking into this, can you do a detailed report on the Tester forums on this please and thank you so we can see if it needs to be reported? Sounds similar to other issues that seem to heavily degrade over time in game.

I'll try and see if I can figure something out that is actually reliably reproducible. Could take until next week though.

[NineLine]

31 minutes ago, Recoil16 said:

I'll try and see if I can figure something out that is actually reliably reproducible. Could take until next week though.

No rush, I appreciate it. Thanks!

[Nealius]

9 hours ago, Zoddom said:

Alright I keep an eye out if it happens again and save the track.

Any idea how I can make the conversion of inHG to mbar easier in the M2000?

 

There's a conversion chart kneeboard somewhere in the User Files. What's easier for me is knowing the destination airfield elevation, and simply subtracting that amount on the altimeter. 1hPA is roughly 30ft. 

 

Example: Current QNH 1013, destination airfield elevation 600ft. 600ft/30ft = 20hPa. 1013hPa - 20hPa = 993hPa. Set altimeter to 993 for QFE.

Edited July 11, 2021 by Nealius

[Recoil16]

On 7/10/2021 at 9:42 PM, NineLine said:

Hey @Recoil16thanks for looking into this, can you do a detailed report on the Tester forums on this please and thank you so we can see if it needs to be reported? Sounds similar to other issues that seem to heavily degrade over time in game.

I've put my findings in the CB forum.

 

For the record of this thread though, it's not a map issue. The Andersen ILS 06L is perfectly fine.

[NineLine]

Thanks @Recoil16

[Nealius]

Revisiting this because now it's happened to me in the Viper on 24L. Exact same issue as the initial post, but different jet and different runway direction: Good localizer but glideslope stuck on the bottom. This is after ~70 minutes of flight and an aerial refueling. Viper ILS on 06L has worked well in my last ~8 approaches, also all in excess of 70-minute flights. I don't understand the randomness of it. Is there a DCS-wide issue with glideslopes going whacko after extended periods of mission time?

 

Track file (recommend fast-foward)

Edited July 19, 2021 by Nealius

[Recoil16]

8 hours ago, Nealius said:

Track file (recommend fast-foward)

You were flying the 06R localizer back course, not the 24L ILS. There's your issue.

Due to (afaik) DCS game limitations, the ILS for 24L is 110.15, not 110.1 as it is IRL. IRL the 06L and 24R ILS and the 06R and 24L ILS use the same frequencies, respectively, but in DCS the 24L/R localizers have .05 MHz added on.

Edited July 19, 2021 by Recoil16
clarification

[Nealius]

9 minutes ago, Recoil16 said:

You were flying the 06R localizer back course, not the 24L ILS. There's your issue.

Due to (afaik) DCS game limitations, the ILS for 24L is 110.15, not 110.1 as it is IRL. IRL the 06L and 24R ILS and the 06R and 24L ILS use the same frequencies, respectively, but in DCS the 24L/R localizers have .05 MHz added on.

 

 

Is the DCS limitation caused by duplicated freqs (06R/24L) not being possible in the code?

 

[Recoil16]

7 minutes ago, Nealius said:

 

Is the DCS limitation caused by duplicated freqs (06R/24L) not being possible in the code?

 

Not so much a code problem in regards to duplicate freqs probably as the fact that all localizers in DCS (to my knowledge) have a back course, unlike many modern systems (like the ones presumably installed at Andersen). IRL you probably wouldn't have been able to pick up the localizer back course at Andersen.

 

But yes, maybe also a code problem.

 

Bottom line though, this latest issue is also not really a bug.

 

Edit: And that kids is why you check the ident of the station you're tuning

Edited July 19, 2021 by Recoil16

[G.J.S]

http://ww1.jeppesen.com/documents/aviation/notices-alerts/chart-alert/PGUA_1803_eChart_Alert_and_Charts.pdf

 

 

[Recoil16]

Just now, G.J.S said:

http://ww1.jeppesen.com/documents/aviation/notices-alerts/chart-alert/PGUA_1803_eChart_Alert_and_Charts.pdf

 

 

How does this contribute to this?

[G.J.S]

14 minutes ago, Recoil16 said:

How does this contribute to this?

ILS Freqs shown, but aside from that approach procedure for those that would like them? I apologise for sharing, won’t happen again.

[Recoil16]

Just now, G.J.S said:

ILS Freqs shown, but aside from that approach procedure for those that would like them? I apologise for sharing, won’t happen again.

All I'm saying is that to me this appears to not contribute anything to the actual discussion of the bug (or not bug as it appears to be). I appreciate that you share these documents, but as far as I know that was already accomplished in another thread. I'm very clear on the IRL ILS freqs, but as I just pointed out, the ones in DCS deviate from that, so in fact these charts will only contribute to the confusion in this specific instance imho.

[G.J.S]

2 minutes ago, Recoil16 said:

All I'm saying is that to me this appears to not contribute anything to the actual discussion of the bug (or not bug as it appears to be). I appreciate that you share these documents, but as far as I know that was already accomplished in another thread. I'm very clear on the IRL ILS freqs, but as I just pointed out, the ones in DCS deviate from that, so in fact these charts will only contribute to the confusion in this specific instance imho.

So by inadvertently providing correct information I overstepped some mark?
Anyway, for those who enjoy procedure, these can be followed - correct freqs or not, should the freqs be left as is.

 

Again, lesson learned, climbing for height - I’m out.