Random DCS lock up (stops responding) with Viggen

[wired521]

I've had 2 issues today with DCS completely locking up while flying the Viggen (eventually causing the entire process to kill).

Both instances occurred when I was near a target area for a fairly simple mission; I've attached my log file for review.

One notable observation from the log was:

 ERROR   VIGGEN (Main): HeatBlur: Assert failed: Value out of range. Pitch stabilization. Was -nan(ind). Expected between -180.000000 and 180.000000

There's an entire block in the log with unexpected values (not always null) - please let me know if you need anything else!

dcs.log

[IronMike]

Thank you. Was this a one off, or can you reproduce it? If you can, the mission file would help. Thanks.

Edited November 2, 2022 by IronMike

[wired521]

Thanks for the reply @IronMike,

It's a fresh installation of DCS and the Viggen (among other modules), and I haven't had this problem with any other modules. I'll do some additional testing this afternoon to see if I can reproduce it - will also attach the mission file. 

It seems to happen after configuring for a dive bomb attack with slick bombs (after setting the master mode to anf), but will see if I can confirm that more definitively. 

[wired521]

Hey @IronMike I've had no luck reproducing this after ~10 sorties. Odd that it happened twice in a row, but not the first time I've seen something odd . Feel free to close the thread - thanks for peaking at the log for me.

[Machalot]

I will speculate this is a floating point precision issue with a degrees-based inverse trig function.  It should accept a value between -1.0 and +1.0, and return between +/-180.0.  But if the input is out of range you get a nan.

@IronMike There was a similar sounding issue about a year ago when the Viggen was temporarily unplayable broken by an OB patch. There was yaw angle out of range that gave a similar error message. Not sure if that is helpful. 

[IronMike]

2 hours ago, Machalot said:

I will speculate this is a floating point precision issue with a degrees-based inverse trig function.  It should accept a value between -1.0 and +1.0, and return between +/-180.0.  But if the input is out of range you get a nan.

@IronMike There was a similar sounding issue about a year ago when the Viggen was temporarily unplayable broken by an OB patch. There was yaw angle out of range that gave a similar error message. Not sure if that is helpful. 

Put down a card for it bud, please, just in case, we should look into it anyways. Thanks!

[Machalot]

20 hours ago, IronMike said:

Put down a card for it bud, please, just in case, we should look into it anyways. Thanks!

Done. 

[PluckyUnderdog]

If it helps, I had this exact same issue with the Viggen yesterday. Flew over a target, bombed it, and was in the process of swivelling my view backwards when DCS froze and I got a 'DCS has stopped responding' and the blue windows loading circle. I had no alternative but to end the program. First time in 6 months DCS has ever done that to me. And I only bought the Viggen a few days ago in the Halloween sale. Strange.