reported ILS and PRGM issues

[draconus]

My speculation is that LSC on the edge of the HUD is no longer reliable (as is velocity vector marker) and gives you the impression that you're still on GS but you're actually understeering - thus drift with the crosswind - which explains the bent flight path.

[Newbie62]

At the risk of expanding the topic...  I tested that theory by using the mission editor to create a copy of the F-15C cannon training mission with reduced wind (but not reduced to 0), so that crosswind effects will be present but the velocity vector and LSC won't get pushed beyond the edges of the HUD.  Following the LSC brought me in pretty much over the runway.  I still crashed because with zero visibility I couldn't tell when to flare after I crossed the runway threshold and lost ILS, and I came in on the right shoulder - to which I may have drifted once I lost ILS, or ILSN may have guided me there.

Topic expansion: while reviewing the track (no need to share it), I tried to change views, F10 to see if ILSN took me off to the right (or was that all me once I lost ILS guidance) and F2 to actually see the plane and runway since from the cockpit it's almost zero visibility due to the weather.  My operating assumption is that I fucked up, but I wanted to see what really happened.

That didn't work.  Which is weird because just the other day when @Ironhand and I were dissecting this, I was doing that all the time: changing the view during replay without taking control.  Now all of a sudden, the view is locked to whatever is recorded in the track.

There hasn't been a game update.  So there is obviously some confounding variable as to whether the view can be changed in replay.  @Flappie, any comment?

[Ironhand]

8 hours ago, Newbie62 said:

…That didn't work.  Which is weird because just the other day…I was doing that all the time: changing the view during replay without taking control…

Sounds like allow external views got set to “no” in Options somehow. You can either open the TRK file with WinZip or something similar and edit the line in the Options file (use NotePad++) or just open the track file in the Mission Editor and select a light cloud preset. Save the track file as a track file with the new clouds. Now you will have visibility from the cockpit with external views locked.

EDIT: Or just post the track and I'll see if I can fix it for you.

Edited May 19, 2023 by Ironhand

[Newbie62]

"Sounds like allow external views got set to “no” in Options somehow."

Maybe, but I started seeing that on all my tracks yesterday.  On the "one more try" at F-15C ISL that I did with reduced wind, and other training missions I ran yesterday in which I ...ahh... didn't do so well and wanted to see just how bad I did.    Now today it has corrected itself, and I didn't do anything to change it one way or the other.  Weird...

[Newbie62]

I went to look at that F-15C "one more try" track just now, and this time I could switch to map and external view.  But the plane flew into the ground during lineup for approach, which isn't what happened.  So I guess the track was corrupted.  Between the arbitrary and persistent blockage of external views that I saw yesterday, and this today with replay not matching what I actually flew and saved yesterday, I suspect a memory corruption bug, that can just whack random bits of state and lead to indeterminate behavior.  As a software engineer, I've been there.  That's why I am a huge fan of valgrind.  I've worked that into continuous integration / regression testing for every project on which I was ever the lead engineer, and even when I wasn't, whenever I could "sell" the concept and get sign-off from the lead to do so...

https://valgrind.org/

[Ironhand]

@Flappie While the focus of Newbie62’s tracks has been the HUD cues, the ADI is obviously non-functional. Lose the HUD and you have no way to make a precision landing in IMC conditions. The pitch steering bar remains locked at the bottom of the ADI throughout. Only the bank steering bar is operative. Neither the glide slope nor course warning flags are in evidence either prior to or immediately after picking up the glide slope, though I don't know if the either should be in evidence.

While flying down the glide slope only the bank steering bar is active. There is no movement from either the pitch steering bar or the glide slope deviation indicator. With 4.3 nm (8 km) remaining in the approach, both the glide slope and course warning flags suddenly appear and the ADI now provides no steering cues whatsoever. The 4.3 nm (8 km) distance is notable because this is the distance at which the ILS needles/bars in all other FC3 aircraft become active not inactive.

I should add that crosswind has nothing to do with any of the above as the behavior is identical with no wind.

EDITED to add TRK file demonstrating ADI/HSI behavior, in case needed.

 

F-15C Preselected ILS Mozdok EDIT Views.trk

Edited May 20, 2023 by Ironhand

[Flappie]

Thank you all for the hard work. @Ironhand, your last track is perfect.

Issue reported.

[Ironhand]

4 hours ago, Flappie said:

Issue reported.

Excellent.

[Flappie]

Hi @Ironhand. Your May 20th track shows a landing a Mozdok, but Mozdok has no ILS, so it seems normal that ILS does not work there. Don't you agree?

Edited May 8 by Flappie

[Ironhand]

14 hours ago, Flappie said:

Hi @Ironhand. Your May 20th track shows a landing a Mozdok, but Mozdok has no ILS, so it seems normal that ILS does not work there. Don't you agree?

 

Duh! Talk about overlooking the obvious.

[Flappie]

Anyway, I was able to reproduce the ADI bug issue at Kutaisi in windy conditions yesterday. Devs acknowledged the issue.

[Ironhand]

36 minutes ago, Flappie said:

Anyway, I was able to reproduce the ADI bug issue at Kutaisi in windy conditions yesterday. Devs acknowledged the issue.

Excellent. I should get around to posting a bug report for the Flanker's ASC Landing Mode. It's been around for years. Or is it something they're aware of?

[Flappie]

1 hour ago, Ironhand said:

Or is it something they're aware of?

I could not find anything related. Please go ahead, create a new thread and feel free to ping me.

By the way, the present thread deals with to different complains:

• The ADI not working in some cases when getting close to the runway (4.3 nm) - reported.
• The ILSN directing the player to the ground - I could not replicate  this issue. Is this still a thing?

[Ironhand]

50 minutes ago, Flappie said:

I could not find anything related. Please go ahead, create a new thread and feel free to ping me.

By the way, the present thread deals with to different complains:

• The ADI not working in some cases when getting close to the runway (4.3 nm) - reported.
• The ILSN directing the player to the ground - I could not replicate  this issue. Is this still a thing?

Thanks for checking. I’ll make a report soon, then.

As for the ILSN directing the player into the ground, I don’t know. Haven’t been in the F-15 cockpit since this thread. If no one else checks, I’ll try to do so soon.

[Ironhand]

On 5/9/2024 at 2:17 PM, Flappie said:

The ILSN directing the player to the ground - I could not replicate  this issue. Is this still a thing?

Yes, if the crosswind component is more than 3 m/s (6-ish knots). It's fine from 0-3 m/s. At 4 m/s, it becomes problematic. The velocity vector will begin flashing from time to time and the system starts leading you off course. It might steady again and bring you back into alignment. Then begin flashing again and leading you off course again. Whether or not you make it to the runway depends on when it fails and when it begins working again. At 6 m/s you're screwed until moments before touchdown, when it suddenly knows where the runway is again. The problem is that the ADI doesn't start indicating the glide slope until 4.3 nm out by which point you might be lost in IFR conditions.

If the real system works this way, fine. But I doubt it. And I'm sure the ADI shows the glide path more than just 4.3 nm out. The ADI in the F-15C and the HSI in the FC3 Russian birds have that same 4.3 (8 km) glide path limitation.

(None of the American birds are my normal ride. So I hope I'm not just doing something wrong here.)

F-15C ILSN 3 ms crosswind OK.trk F-15C ILSN 4 ms crosswind Problematic.trk F-15C ILSN 6 ms crosswind Fail.trk

Edited May 17 by Ironhand

[Flappie]

Thanks a lot!

[Flappie]

19 hours ago, Ironhand said:

The ADI in the F-15C and the HSI in the FC3 Russian birds have that same 4.3 (8 km) glide path limitation.

Do you have a track showing the ADI issue in a Russia bird? I've just tried the Su-27 and it looks rather OK (at least, the horizontal bar is moving - it does jump from time to time, though).

 

Su-27 ILS ok.trk

[Ironhand]

4 hours ago, Flappie said:

Do you have a track showing the ADI issue in a Russia bird? I've just tried the Su-27 and it looks rather OK (at least, the horizontal bar is moving - it does jump from time to time, though).

 

Su-27 ILS ok.trk 693.72 kB · 0 downloads

In the F-15C, it's the ADI that gives you the ILS bars. In the Russian birds, it's the HSI rather than the ADI that has them. In both, they don't come alive until, magically, at 8 km (4.3 nm) from the runway.

Fast forward to 9km from landing. At 8 km from the runway, it'll magically come alive even though the HUD says it has the localizer and glideslope beams dialed in right from the initial transition from Return to Landing mode. The same thing is happening with the ADI in the F-15.

Flanker AP Landing Mode Test Maykop.trk

[Flappie]

Thanks, now I see it.

Edited May 17 by Flappie

[Flappie]

Yes, I corrected my post anyway because, like Ironhand said, other instruments already get the glideslope signal correctly way before 4.3 nm.

Thank you.

[Flappie]

I'll report this but first I'm testing all FC3 aircraft. It seems the MiG-29S never gets the ILS signal. Am I doing something wrong?

MiG-29S no ILS.trk

[draconus]

9 minutes ago, Flappie said:

I'll report this but first I'm testing all FC3 aircraft. It seems the MiG-29S never gets the ILS signal. Am I doing something wrong?

MiG-29S no ILS.trk 436.43 kB · 0 downloads

I didn't check the track but russian birds don't use ILS. They use RSBN/PRMG instead which is supported on 4 Caucasus airports only. Check the table here:

Note the blue numbers - some are only one direction, ex. Krasnodar-Center RWY 09.

 

btw: I tried to look for anything official on the ILS glideslope signal range.

https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap1_section_1.html

"The glide slope is normally usable to the distance of 10 NM. However, at some locations, the glide slope has been certified for an extended service volume which exceeds 10 NM."

Edited May 17 by draconus

[Flappie]

Thanks a lot. PRMG issue reported (HSI catches the signal 7.6 km away from the runway, when the HUD catches it 17 km away).

Affected aircraft: Su-25T, Su-25, Su-27, MiG-29, Su-33.

By the way, it just occured to me that the ILS issue also affects the A-10A.

 

Let's sum up this thread. 3 issues are now reported:

• F-15C ILSN does not work with a 20 kmh crosswind.
• Sometimes, the F-15C and A-10A ADI vertical bar does not work, then the ADI bars are stowed 4.3 nm ahead of the runway.
• For all Soviet aircraft, HSI gets the PRMG signal later than the HUD (7.6 km ahead of the runway).

Edited May 17 by Flappie

[draconus]

On 5/16/2024 at 5:56 AM, Ironhand said:

At 4 m/s, it becomes problematic.

13 minutes ago, Ironhand said:

And at 4 kmh crosswind it's already problematic in my tests.

Please decide or you got lost on the unit conversions? 5.5m/s is around 20km/h.

Edited May 17 by draconus

[Ironhand]

1 hour ago, draconus said:

Please decide or you got lost on the unit conversions? 5.5m/s is around 20km/h.

 

Yes. I wasn't fully awake yet, when I wrote that. I was lost in the units.