A lot of new planes have LED strobes that are in sync...

I'm having a similar problem. When using Vladimir Gonchar's FSX version ("Touch O' Texas") of the Shupe/Thomas Beech 18 freeware aircraft, the beacon light creates flashes in the cockpit also. This is quite annoying in flight so I have to turn the beacon light off always. Does anyone know if this can be fixed as well so the light doesn't flash inside of the cockpit?

I think Premier Aircraft Design came up with a beacon effect for their aircraft that does not produce a flash inside the cabin.  You might try downloading one of their more recent aircraft and trying their beacon effect.

stans: Thanks for the tip! With a little bit of digging, I found a couple of articles [1] [2] that informed my inexperienced self how to replace that beacon light. I already had an instance of the PAD beacon light in my effects folder from a prior freeware aircraft download, and I simply replaced all instances of 'fx_beacon.fx' in the Beech 18 aircraft.cfg file with ''fx_PADbeaconh.fx' instead.

 

It worked like a charm! The light isn't flashing in the cockpit anymore but is flashing on the outside of the aircraft. I haven't caught any glitches with this yet. The only thing I noticed is that the wings also get a soft light outside of the aircraft when the beacon is turned on. I'm not sure if that's normal, but it doesn't bother me at all. I'll post here if I run into any other problems (but I don't expect I will).

 

Thanks again!

Yeah!  I helped someone!  Glad it worked out for you.