[NO BUG]No CV alignment possible in GPS restricted environment

It currently (version 2.5.6.49798) is not possible to perform a valid INS alignment on a moving aircraft carrier without GPS (meaning in a mission prior to 1994 or on REDFOR side with UNRESTRICTED SATNAV deactivated). This is driving me nuts as I would love to play carrier based missions without GPS, like MBot's Dynamic Campaign, which takes place in 1990!

I'm aware that the navigation system in the Hornet is still WIP, but missing something as essential as the ability to perform GPS-less carrier alignments two years after the module's EA release is pretty frustrating.

In the past there was the workaround to perform a TACAN FIX, as BIGNEWY explained here, unfortunately that doesn't work anymore for some reason...

I attached a very simple test mission with a cold start Hornet on a carrier, where one can test it. It's just not possible to get aligned properly! A TACAN FIX does not work with the carrier nor the nearby Al Minhad TACAN station.

The best thing you can do is to perform a NAV FIX on WYPT 0, but that is inaccurate as you have moved away from WYPT 0 by the time you can perform the NAV FIX. It's even more inaccurate in the abovementioned campaign, as you have a pre-briefed launch time, which is ~15 minutes after you spawn in, meaning you will have drifted much further at the time you start up your aircraft...

Test.miz

It currently (version 2.5.6.49798) is not possible to perform a valid INS alignment on a moving aircraft carrier without GPS (meaning in a mission prior to 1994 or on REDFOR side with UNRESTRICTED SATNAV deactivated). This is driving me nuts as I would love to play carrier based missions without GPS, like MBot's Dynamic Campaign, which takes place in 1990!

 

I'm aware that the navigation system in the Hornet is still WIP, but missing something as essential as the ability to perform GPS-less carrier alignments two years after the module's EA release is pretty frustrating.

 

In the past there was the workaround to perform a TACAN FIX, as BIGNEWY explained here, unfortunately that doesn't work anymore for some reason...

I attached a very simple test mission with a cold start Hornet on a carrier, where one can test it. It's just not possible to get aligned properly! A TACAN FIX does not work with the carrier nor the nearby Al Minhad TACAN station.

The best thing you can do is to perform a NAV FIX on WYPT 0, but that is inaccurate as you have moved away from WYPT 0 by the time you can perform the NAV FIX. It's even more inaccurate in the abovementioned campaign, as you have a pre-briefed launch time, which is ~15 minutes after you spawn in, meaning you will have drifted much further at the time you start up your aircraft...

This has been reported a while ago. But looks like we'll have to live with this until (if) they get to implement proper INS. Sorry :(

This has been reported a while ago. But looks like we'll have to live with this until (if) they get to implement proper INS. Sorry :(

I know, but what about the TCN workaround? It worked in the past, but not anymore for some reason... :noexpression:

Otherwise I would have to wait until somewhere in 2021 in order to be able to enjoy the abovementioned campaign and other cold war missions :(

DCS: F/A-18C Hornet Improvements in 2021:

[...]

22. INS / GPS full simulation and alignment (carrier and ground)

Seems to be working for me.

 

Updated using DSG and using TCN

 

If you are using TCN make sure it is On and selected, so it is saved in the MC

 

in your mission I changed the tacan to 71 for the CV and it worked

I tried again, this time with 71X, but the TCN FIX still didn't work. The DSG fix does work, as I mentioned above, but is inaccurate for a carrier alignment, as the aircraft will have moved away from WPT 0 by the time the DSG FIX can be executed.

In your screenshot there is no way to tell if you have actually made a TCN FIX or just an inaccurate DSG FIX.

For the TACAN FIX I attached a track file, where you can see how I did the following:

1) Perform CV alignment for 1:40 min, then switch the INS to NAV. No map is shown on the HSI.

2) Dial in the TACAN of the carrier.

3) Execute a TCN FIX on the carrier. Nothing happens. TCN was ON (range and bearing as well as the audio signal were there) and selected.

4) Execute a DSG Fix on WP1, in order to have a substantially inaccurate own position, which is more obvious than the inaccurate position of WP0 would be.

5) Execute another TCN FIX in order to correct the own position. Nothing happens.

Either I'm doing something wrong when executing a TCN FIX or the TCN FIX isn't working at all. :dunno:

TCN UPDT Test.trk

semi-OT question: how would a TCN fix work if the carrier tacan is used? I mean, the carrier tacan is moving together with the vessel and therefore not a "fix" point that the alignment process could use as a reference. Or am I missing something here?

semi-OT question: how would a TCN fix work if the carrier tacan is used? I mean, the carrier tacan is moving together with the vessel and therefore not a "fix" point that the alignment process could use as a reference. Or am I missing something here?

No, you're absolutly right. The whole NAV FIX system of the Hornet is borked and doesn't make a whole lot of sense.

The issue of not being able to get a properly aligned nav system on a carrier doesn't just affect navigation, but also CCIP accuracy (and probably JDAM accuracy as well):

Well I just flew a bunch of full campaign missions in the Hornet and noticed that while the WP0 designation method will fix the navigation system, it will not fix the twisted CCIP. This just goes to show how little I have actually flown the Hornet since the Tomcat was released. From land the WP0 designation works well also for CCIP, but from the carrier I see no other way to align the ballistics computer.

 

So did ED really purposely disable the Hornet's bombing capabilities when launching from a carrier pre-1993?

I would really like to get some info on how exactly one is supposed to get a properly aligned nav system in a GPS restricted environment...

BIGNEWY says a TCN FIX should work, but it has no effect at all in my tests. I would love to know why that is...

Can the red side use GPS munitions since they don't have GPS capability? I'm guessing no.

Can the red side use GPS munitions since they don't have GPS capability? I'm guessing no.

They can, as GPS munitions are actually INS/GPS munitions. They just need a properly aligned nav system. That can be achieved by performing a DSG FIX after alignment when starting on the ground. When starting on a carrier they will have the same issue I have reported here, unless UNRESTRICTED SATNAV is enabled in the mission editor.

I don't understand why this is tagged as NO BUG, as this is CLEARLY a bug. The INS when starting on a carrier pre-1994 is borked, resulting in very inaccurate positioning, the twisted CCIP issue, and a plethora of other positioning-related problems. @BIGNEWY please un-tag this as no bug, and forward to the development team for a fix!

I don't understand why this is tagged as NO BUG, as this is CLEARLY a bug. The INS when starting on a carrier pre-1994 is borked, resulting in very inaccurate positioning, the twisted CCIP issue, and a plethora of other positioning-related problems. @BIGNEWY please un-tag this as no bug, and forward to the development team for a fix!

... or explain how to properly perform a TCN-FIX, as you (BIGNEWY) are saying that it works, because for me it doesn't work, as I described in my previous posts. The manual (or EA guide), doesn't say anything about it either.

So, has anyone managed to get the TCN FIX to work in the current build? Because I still can't get it to work. It very much looks like to me that this feature is broken in the current build, despite BIGNEWY's assertion that it does work.

I don't know what else I can do to proof that this is in fact a bug. I have described the problem, have listed steps to reproduce it and uploaded a track of me demonstrating it as well as a mission for anyone to test it. So what else can I do?

I would also be interested to know how to align the align the INS on a carrier without GPS. I can get the nav system (correct own position and distances to waypoints) working with a DSG fix, but the CCIP remains all screwed up.

I can get the nav system (correct own position and distances to waypoints) working with a DSG fix

Are you sure about getting correct own position and distances with a DSG fix? I'm asking, because in my tests this was not the case as I described here: https://forums.eagle.ru/showpost.php?p=4356247&postcount=5

The DSG fix will take the position of the waypoint it is performed on. Usally that is WP0 and that works fine if the aircraft hasn't moved since it spawned. That is not the case though on a moving carrier, because the aircraft will have traveled away from WP0 with the carrier by the time one can perform a DSG fix when starting cold as it takes a bit to boot up the aircraft and its systems. If all this is done as fast as possible the inaccuracy of the DSG fix will only be a few hundred meters, as this is how far the carrier will travel in that time. Although its just off by a few hundred meters it is not an accurate own position!

However in some missions you might want to wait with aircraft startup. That is the case in your Dynamic Campaigns, as they give the player a pre-briefed launch time, that is ~15 minutes after spawning in. So in order to save fuel I wait 10 minutes before I startup my aircraft. By that time I will have travelled much further away from WP0 and the DSG fix will be much more inaccurate!

This is why I would like to be able to correct this inaccuracy of the nav system somehow and that's what the TACAN-fix was used for in earlier builds, but in the current DCS build the TCN-fix doesn't work anymore! It just has no effect anymore @BIGNEWY!

The DSG fix will take the position of the waypoint it is performed on. Usally that is WP0 and that works fine if the aircraft hasn't moved since it spawned. That is not the case though on a moving carrier, because the aircraft will have traveled away from WP0 with the carrier by the time one can perform a DSG fix when starting cold as it takes a bit to boot up the aircraft and its systems. If all this is done as fast as possible the inaccuracy of the DSG fix will only be a few hundred meters, as this is how far the carrier will travel in that time. Although its just off by a few hundred meters it is not an accurate own position!

Indeed you will travel a few hundred meters with the carrier before you can perform a DSG fix on WP0. But for navigation I consider this accurate enough. If ED would actually simulate INS drift like Heatblur does with the F-14, you would have similar errors anyway after a while in flight. Even a TACAN fix on a fixed station (if it workes) would technically not be able to produce a position fix that is more accurate then a few hundred meters. A TACAN fix with a moving station (carrier) doesn't make sense anyway, since the position of the station is unknown.

The big practical problem I see is that the dumb bomb computations don't work without GPS.

Indeed you will travel a few hundred meters with the carrier before you can perform a DSG fix on WP0. But for navigation I consider this accurate enough.

That's right for most cases, but an offset of a few hundred meters can be critical in certain situations (e.g. employment of PGMs or low level strikes where the target will only be visible at the very last moment). Also we're talking about the initial position here, which is already inaccurate. Drift would accumulate in addition of this initial offset and this initial offset will be even greater if you don't start up the aircraft right away as I explained in my previous post.

Even a TACAN fix on a fixed station (if it workes) would technically not be able to produce a position fix that is more accurate then a few hundred meters.

Absolutly true, but currently the TACAN fix doesn't seem to work at all in the Hornet...

A TACAN fix with a moving station (carrier) doesn't make sense anyway, since the position of the station is unknown.

Absolutly true again, which is why I actually used land based TACAN stations as an example in my initial post, but then BIGNEWY said, that it also works just fine with TACAN fixes on a carrier, so I tried that then, which didn't work either.

The big practical problem I see is that the dumb bomb computations don't work without GPS.

Yeah, it's another issue of not being able to obtain a accurate NAV system on a moving carrier atm.

@MBOT, I don't know exactly what the mechanical differences are between the INS of an airliner and the INS in the F/A-18C, but usually INS drift doesn't begin to occur until either several hours have passed, or a few thousand miles have been traversed. Most missions with an F/A-18C would realistically begin to see some slight INS drift... right around the time you arrive safely back to the carrier. A couple hundred meters difference after a 2 hour flight would be pretty severe in a precision aircraft.

INSs begin to drift immediately. With commercial aircraft, enough tolerance is/was built into separation standards that it would only start to become problematic after multiple hours without an update. But the INS does indeed drift the entire time, it doesn’t suddenly jump out to a couple nm error after 5 hours. Drift rates of up to 2nm/hr are not uncommon in older INS systems of the 70s & 80s.

It would seem that ED need to implement the CV datalink alignment feature to have a working solution to this issue. Hopefully this could be done as the first step to an overall improved INS simulation, as it would at least get aircraft airborne with working systems, with the detailed system to follow.

It would seem that ED need to implement the CV datalink alignment feature to have a working solution to this issue. Hopefully this could be done as the first step to an overall improved INS simulation, as it would at least get aircraft airborne with working systems, with the detailed system to follow.

Yes, that would be the ultimate goal, but ED implemented the TACAN-fix as a workaround, which did work in the past to get a precise nav system when starting on a moving carrier. The problem is, that this workaround isn't working anymore and ED either doesn't understand that or doesn't care :(

Until about a year or so ago, no workarounds were required at all and you could simply align your INS on the carrier. When I created my 1990 Hornet campaign, it was fully playable with working navigation and bombing.

Then it seems the INS alignment process was made dependable on the availability of GPS. This I was an absolutely thoughtless move without also implementing the alternative carrier alignment process when no GPS is available.

The easiest solution would therefore be to remove the GPS requirement again until ED later programs the proper CV alignment process (where your aircraft links to the carrier's INS for alignment).

Until about a year or so ago, no workarounds were required at all and you could simply align your INS on the carrier. When I created my 1990 Hornet campaign, it was fully playable with working navigation and bombing.

 

Then it seems the INS alignment process was made dependable on the availability of GPS. This I was an absolutely thoughtless move without also implementing the alternative carrier alignment process when no GPS is available.

 

The easiest solution would therefore be to remove the GPS requirement again until ED later programs the proper CV alignment process (where your aircraft links to the carrier's INS for alignment).

I don't think that would be a good idea, as this would be a global change, possible effecting other aircraft as well. I would prefer Hornet specific fixes, as it is the implementation of the NAV system in the Hornet that is lacking functionality.

Btw, if your interested how the GPS restriction got implemented you can read through the following thread, where those global GPS changes were discussed and requested: https://forums.eagle.ru/showthread.php?t=250276

Still no response from ED? I'm extremely disappointed in the devs handling of this. Major game-breaking bug, and ED basically says it's a feature.

Still no response from ED? I'm extremely disappointed in the devs handling of this. Major game-breaking bug, and ED basically says it's a feature.

Probably because there's no real easy fix for the issue. It would be a huge task to develop a complete & accurate INS simulation, including CV datalink. Given 95% of people never fly the Hornet without GPS, it's not affecting enough people for ED to acknowledged it needs work.