Compass re-sync after launch

[Jar72]

 Hello @Reflected, @IronMike, everyone (!),

In Bio's book "Tomcat Rio", he mentions one time where his pilot forgot to "sync" the compass after taking-off, in order to compensate for the magnetic deviation due to the carrier, and resulting in an offset of 60 Nm in their navigation. Or so I understand.

I noticed this offset myself early in the sim (bravo to Heatblur's fidelity !), but only after reading this book did I understand why and how to correct it. Now I always "sync" it after launch.

But, it seems to me that very few missions take this into account. So, sometimes the bearing from the Awacs is off, or the navigation waypoint, and sometimes it is right on point. A good example is mission 3 in HB's campaign in South Atlantic. Jester tells you to head 010, but with magnetic deviation to aim at 350. One can understand why finding the A-4 / Mig-21 in the valley can be tricky then, with 20° difference.

• So I am wondering : is the resync after launch a standard procedure ? I do not find it in the check list Reflected provided from Navair, and none of the campains refer to it. But then why not ? It seems quite mandatory, doesn't it ?
• Are bearing calls magnetic or true heading by the Awacs of DCS AI ? Do the calls by Jester, Bio, Paco, any scripted sentences... refer to Magnetic heading in A/C or True ? If Magnetic, do they take into account the re-sync ? In real life, should they be True, or Magnetic for simplification ?

• Should this sync procedure implemented in campains, with sometimes "problems" if they are not (like in the book) ?

 

Actually, this has embarassed me for 2 years and now I feel lost. No, sorry, a pilot never is. Let's say I'm momentarily uncertain of my position.  And since you guys are (close to) Gods in realism, I guessed I could ask for a quick vector (true or magnetic) to Mother please ?

Thanks a lot in advance for the clarification.

JAR

 

PS : The button I am referring to is the :

5. HDG knob/button

 In SLAVED mode it’s used to sync the directional gyro with the magnetic azimuth detector and set magnetic heading on the BDHI. Button should be held until the syncronization indicator needle is over the null mark.

https://www.heatblur.se/F-14Manual/cockpit.html#rsc

 

PS bis : In the documentation, in normal operation (but INS mode) all systems show Magnetic heading :

 

Bearing Distance and Heading Indicator (BDHI)

A BDHI is on the right side of the pilot and RIO instrument panels, see Bearing Distance Heading Indicator (BDHI). It displays aircraft magnetic heading with navigation bearing data and range information.

Note

• In the INS nav mode IMU true heading is used and must be converted to magnetic heading by adding or subtracting the magnetic variation to have a backup magnetic value, if needed. Under normal operation, AHRS magnetic heading is used for all displays.

[Ivandrov]

The compass resync is something I do as standard after reading about it in the Heatblur Manual. It's something more than likely that you are expected to do rather then the campaign necessarily holding your hand about it, but I don't know anything about this campaign. But the button itself is not really a "start sync" button, more like a "fast sync", as the jet will automatically compensate for changes in magnetic variance on it's own as you fly, even eventually correcting the drift caused by the Carrier if you fly for long enough. The button increases the sync rate when you have your jet in a proper flight profile for it.

I can't comment on any specific mission, but the DCS AI AWACS gives it's BRA callouts in True Heading which I've confirmed just now through testing. I would assume Jester's callouts are in Magnetic as long as they are the Jester AI callouts and not a scripted callout by the mission.

Waypoints in any mission are placed in the Mission editor in their absolute locations. If there's a problem in the jet that causes you to miss it by 20 degrees, that's probably on you. The most drift of the calculated magnetic variance that I usually see is about 10 degrees.

Edited December 26, 2024 by Ivandrov

[Reflected]

You need to sync the compass when you leave the magnetic field of the carrier, and you're flying straight and level. I do it at 7 miles. It's not part of the official checklists, it's jsut a thing you do regularly. There's nothing to 'implement' in the campaigns, it's already a feature of the F-14 module

[RustBelt]

The problem is it doesn’t seem like the needle changes. Having flown primitive Flux Gate HSI rigs I’m accustomed to checking the drift needle and it never seems to be out of whack like it should be. 
 

Once you’re clear of the boat shouldn’t that thing be cranked way over on one side?

Edited December 26, 2024 by RustBelt

[Whiskey11]

9 hours ago, RustBelt said:

The problem is it doesn’t seem like the needle changes. Having flown primitive Flux Gate HSI rigs I’m accustomed to checking the drift needle and it never seems to be out of whack like it should be. 
 

Once you’re clear of the boat shouldn’t that thing be cranked way over on one side?

You have to be going at a constant velocity and perfectly level.  Generally speaking, I set autopilot and dish the throttle back quite a lot. The needle WILL move to show the variation from the carrier's magnetic influence. 

[Jar72]

12 hours ago, Reflected said:

You need to sync the compass when you leave the magnetic field of the carrier, and you're flying straight and level. I do it at 7 miles. It's not part of the official checklists, it's jsut a thing you do regularly. There's nothing to 'implement' in the campaigns, it's already a feature of the F-14 module

Hi @Reflected, thank you for your answer. So I do the right thing by resync, good ! 

Sorry, I was not very clear, my proposal was not related to the feature itself to implement, but the learning of the procedure to do it. As I did not know it s something to do until recently, maybe others feel the same. I thought that this could be mentioned somewhere. Maybe in this thread :-). Maybe in a tuto. Maybe in a mission. That s what I meant by implementing in a campaign. For instance, how about Paco mentioning it, and then you setup a "trap" 3 missions later ? You have a cap to maintain, you are off by 60 Nm, you're in the wrong territory, problems start... Just an idea. Absolutely no disrespect nor suggesting of what you should do.

You are the judge on this. I m already honored you took the time to read and answer me.

 

@Ivandrov thank you for your answer as well, I learned a lot and it answers my question about true vs magnetic heading calls. Just to clarify please, I never meant it as a "problem", as you wrote it. I just raised my hand for help. Please do not change the meaning of my intent. I feel so sad by reading too many negative comments too often, I do not want to start a new one. I am very grateful to Ed, Dcs, Heatblur and Reflected, I am sorry if wrong was taken, or if it seemed I was criticizing. I spent 1 hour to write my message to prevent this exactly. And 1 hour again for this one. Thank you for your understanding.

 

Anyway, thank you all again for your time and help. It was not a trivial subject for me.

 

[The_Tau]

 

Edited December 26, 2024 by The_Tau

[Jar72]

Oh my gosh, this is perfect. I know faw content but not this video.

It kind of confirms my point, doesnt it? Not everyone knows about it and it s not widely documented if I may. Effect of de-sync can be important. So yes, this video is great great great. I would recommand more spreading of it. Maybe refer to it in guides, like chuck's, or my previous suggestions.

Thanks again.

Have a nice one.

 

 

[Ivandrov]

4 hours ago, Jar72 said:

Hi @Reflected, thank you for your answer. So I do the right thing by resync, good ! 

Sorry, I was not very clear, my proposal was not related to the feature itself to implement, but the learning of the procedure to do it. As I did not know it s something to do until recently, maybe others feel the same. I thought that this could be mentioned somewhere. Maybe in this thread :-). Maybe in a tuto. Maybe in a mission. That s what I meant by implementing in a campaign. For instance, how about Paco mentioning it, and then you setup a "trap" 3 missions later ? You have a cap to maintain, you are off by 60 Nm, you're in the wrong territory, problems start... Just an idea. Absolutely no disrespect nor suggesting of what you should do.

You are the judge on this. I m already honored you took the time to read and answer me.

 

@Ivandrov thank you for your answer as well, I learned a lot and it answers my question about true vs magnetic heading calls. Just to clarify please, I never meant it as a "problem", as you wrote it. I just raised my hand for help. Please do not change the meaning of my intent. I feel so sad by reading too many negative comments too often, I do not want to start a new one. I am very grateful to Ed, Dcs, Heatblur and Reflected, I am sorry if wrong was taken, or if it seemed I was criticizing. I spent 1 hour to write my message to prevent this exactly. And 1 hour again for this one. Thank you for your understanding.

 

Anyway, thank you all again for your time and help. It was not a trivial subject for me.

 

It was a problem in the jet I was specifically referring to as the 20 degrees drift that you mentioned is too extreme for it to be the error caused by the carrier or airfield. About 10-15 is what I usually see.

 

As far as putting it in a mission. You can probably reference it as an incident that happened to someone else in the squadron, as kind of idle chatter if that's something that a mission maker wants to do. I would not be a fan of being directly reminded to do it if I already know about it from reading the manual on day one and have incorporated it into my usual procedures.

Edited December 26, 2024 by Ivandrov

[Jar72]

I did not write 20 degrees drift. I mentioned I was lost between true and mag heading calls, depending on who calls, and whether Re sync has been done. I highlighted my question with an example. Sorry if I was not clear enough, but it was no trivial subject for me. I think we are on the same page now, no harm done, or so I hope.

Jester tells you to head 010, but with magnetic deviation to aim at 350.

 

I guess you are not a fan of any campaigns then. Because often in them, including reflected, heatblur, sandworm, and I m still a big fan 2+ years later, jester or chig or... briefs you about the case I pattern. Yet I read it from the manual way before knowing about resync.

Sorry, it is a joke, don t take it personally but everybody has an opinion. Yours is different, I respect that. Let me clarify again my original intention with my proposal. I believe the re sync procedure is not well known, and I suggested the community could benefit from learning it in one way or another. Your first answer and the video are great. I hope it can help others like me. I believe we can close this post ? 

Thanks again to everybody for sharing and taking the time.

Cheers

Jar

 

Edited December 26, 2024 by Jar72

[Reflected]

7 hours ago, Jar72 said:

Hi @Reflected, thank you for your answer. So I do the right thing by resync, good ! 

Sorry, I was not very clear, my proposal was not related to the feature itself to implement, but the learning of the procedure to do it. As I did not know it s something to do until recently, maybe others feel the same. I thought that this could be mentioned somewhere. Maybe in this thread :-). Maybe in a tuto. Maybe in a mission. That s what I meant by implementing in a campaign. For instance, how about Paco mentioning it, and then you setup a "trap" 3 missions later ? You have a cap to maintain, you are off by 60 Nm, you're in the wrong territory, problems start... Just an idea. Absolutely no disrespect nor suggesting of what you should do.

You are the judge on this. I m already honored you took the time to read and answer me.

 

@Ivandrov thank you for your answer as well, I learned a lot and it answers my question about true vs magnetic heading calls. Just to clarify please, I never meant it as a "problem", as you wrote it. I just raised my hand for help. Please do not change the meaning of my intent. I feel so sad by reading too many negative comments too often, I do not want to start a new one. I am very grateful to Ed, Dcs, Heatblur and Reflected, I am sorry if wrong was taken, or if it seemed I was criticizing. I spent 1 hour to write my message to prevent this exactly. And 1 hour again for this one. Thank you for your understanding.

 

Anyway, thank you all again for your time and help. It was not a trivial subject for me.

 

I agree, Paco could have mentioned it during the qual missions but somehow it didn’t even occur to him when he wrote the script. Perhaps it’s so ‘basic’ or ‘second nature’ for Naval Aviators? I mean they have to know the NATOPS inside out while we just play through a few missions

Again, I cannot influence this drift feom the mission editor. Also please note that the INS will drift if you pull too many g-s, and also if you start the alignment while the ship is turning into the wind .

 

[RustBelt]

No let’s be real. The Manual, that was put up as HTML because the intent was to revise it regularly, has been basically forgotten on the “After we’re out of Early Access” pile with a LOT of stuff.

[Nealius]

Sadly a theme across the entire DCS ecosystem.

Once I discovered the functionality of that button I started doing it as part of my CASE I departure procedure. Once level parallel BRC at 500ft 300kts I turn on the autopilot and press that sucker.

CASE III is trickier. I haven't found a good time to do it because it requires straight-and-level flight, which isn't achieved until hitting my departure radial. But even at 20 miles away from Mother, there's enough compass error that my actual position differs from the departure radial I should be on once I do level off and sync the compass. I remember someone in another thread claiming the TACAN CRS line is unaffected by the magnetic field, but this is false. The CRS deviation line references your compass, error/desync included.

Edited December 30, 2024 by Nealius

[RustBelt]

The course line doesn’t represent magnetic (at least it shouldn’t)  but you have to fly to center the needle on a set radial, not use it as an HSI. Whatever weird looking heading gives you an outbound course on the BRC radial you just hold even if it looks way out of whack.