You cannot shoot Santa down. You blow yourself up.
You shoot the presents and get perk points!
I have flown near him a few times years ago and there is a truce called so you don't shoot enemy planes flying with Santa. I and others would have kids with them showing Santa dropping gifts and is really bad form to shoot down enemy during that.
If I remember right, in the past Dale would make 3 runs. 6 PM, 9 PM and midnight all US Central time, Dallas TX.
But I am not sure about this year...