Interesting observation. I always take note of the ACARS OOOI times for my records. Pushed back at 2058, ACARS recorded it precisely. Took off at 2117, ACARS recorded it precisely. Aircraft was the 747-8i.

Then, the sun set shortly after takeoff from JFK (destination FRA) and my FPS did drop to single digits (for some reason, during dusk and dawn I seem to have this issue although other times of the day I have 50-60 FPS in the VC of any complex aircraft, any scenery).

The low FPS must have caused the already recorded ACARS times to change. I checked an hour and a half after takeoff and the values changed like this:

OUT changed from 2058 to 2105
OFF changed from 2117 to 2123

Also the constantly updating flight time and block time counters in the lower right corner of the ACARS OOOI status page were no longer accurate, in fact, were showing 6-7 minutes less than the actual, respective elapsed times.

I think the built-in clock in the aircraft is somehow affected by the low FPS and that's why it happened.

I am gonna upgrade my GTX 1070 to a GTX1080ti soon, hopefully the sunrise/sunset FPS issue will be gone too. I have been having it since I switched to P3D in 2016 although for some reason I did not have FPS loss from late 2017 until June 2018, when I left P3D in favour of DCS. Then I returned a month ago, fresh install, everything up-to-date... and the dusk/dawn FPS nosedive is back too. Wish I knew what is the main cause.

Edited February 14, 20197 yr by kityatyi

There's some intentional messing about with the times to ensure everything matches up if people mess with the times (intentionally/unintentionally).

Think of it this way: someone takes off at noon and shifts the clock to 1800, flies for 4 hours, and then lands and parks for a total of 5 hours between takeoff and landing. The total actual flight time is 4 hours; block time is 5 hours. Without adjusting the clock times, you'd see that the flight time was 10 hours, and block time 11 hours.

5 minutes ago, scandinavian13 said:

There's some intentional messing about with the times to ensure everything matches up if people mess with the times (intentionally/unintentionally).

Think of it this way: someone takes off at noon and shifts the clock to 1800, flies for 4 hours, and then lands and parks for a total of 5 hours between takeoff and landing. The total actual flight time is 4 hours; block time is 5 hours. Without adjusting the clock times, you'd see that the flight time was 10 hours, and block time 11 hours.

Makes perfect sense.

It's obvious that this clock self-adjustment was caused by my low FPS since it was the first time I flew the 748 during dusk/dawn - that killed my performance. I need to cure the root of this issue, and hopefully the 1080ti will take care of that.

Thanks for your reply!

7 minutes ago, kityatyi said:

Makes perfect sense.

It's obvious that this clock self-adjustment was caused by my low FPS since it was the first time I flew the 748 during dusk/dawn - that killed my performance. I need to cure the root of this issue, and hopefully the 1080ti will take care of that.

Thanks for your reply!

the 1080ti can't do magic. I had the GTX970 before and never had any FPS drops related to dawn or dusk. WHAT I had were FPS drops and stutters when ORBX lights were loaded. But I still have them even with the 1080Ti now. 

what you COULD do (which helped me a bit) is experimenting with the fiber_frame_time_fraction tweak. avsim and other forums have many discussions and a lot of advice on this. Also preload and texture tweaks can help if set up correctly according to your system. 

6 minutes ago, Ephedrin said:

the 1080ti can't do magic. I had the GTX970 before and never had any FPS drops related to dawn or dusk. WHAT I had were FPS drops and stutters when ORBX lights were loaded. But I still have them even with the 1080Ti now. 

what you COULD do (which helped me a bit) is experimenting with the fiber_frame_time_fraction tweak. avsim and other forums have many discussions and a lot of advice on this. Also preload and texture tweaks can help if set up correctly according to your system. 

Thank you for the advice, really appreciate it! I will look into this!