No IFR GPS uses Glonass AFAIK. Or Galileo for that matter…
It would depend on who did the launch. If it was N Korea, all GPS would be shut down immediately.
If it was Russia, they would not want anybody else to use Glonass to shoot at them so that would be gone too 
But in any of these scenarios, GA would be banned in Day 1, like it was in WW2, so this isn’t an issue, so the fact that nobody actually knows the answer is not important.
If the launch were one cruise missile by Daesh?
Don’t they always give 45 minutes warning?
And if you are more than 45 mins from the nearest suitable airport and you only have RNAV approaches as destination and alternate?
Actually, given 45 minutes warning, what proportion of airborne aircraft could you land, if they all need GPS?
The 45 minutes I was alluding to are in connection with the well-known users of WMD.
I lost GPS during the LPV at LFLY 16 today at about 700 ft agl. Reported to tower who said there had been other reports and they suspected jamming. Fortunately it was a nice CAVOK day so continued visually.
This is from today’s flying – Garmin Aera 660
So much for Glonass… it’s barely relevant.
Noe wrote:
I lost GPS during the LPV at LFLY 16 today at about 700 ft agl. Reported to tower who said there had been other reports and they suspected jamming. Fortunately it was a nice CAVOK day so continued visually.
The penalties are quite severe in the US if one is caught importing, selling, or using a GPS jammer. See this Notice local copy. The jammer is broadcasting their position and can be detected with the right equipment, so reporting to the authorities is important.
Unfortunately, Europe has actual and potential incentives for jamming GPS. One is apparently to prevent recording truck mileage, so drivers can drive for longer than the maximum legally allowed time. A really big one will come if/when road pricing is introduced, based on GPS feedback of vehicle position; jamming will then become widespread.
