I collected all the rules from GURPS 4e for flying, high speed, and mounted combat into one document here:
https://empireofnightnewdawn.fandom....Mounted_Combat
There are some house rules in there (the Dragon rule, the distinction between wiping out and losing control, treating dives as turns, and some others) but it's a good place to start. Though the Dragon Rule is just expanding the ability that Griffons already have in DFRPG to all flyers.
My group used these rules for a massive aerial dogfight (6 PCs on pegasi and giant eagles, 6 NPC fighter-wizards on pegasi and dragonback) which was a little complicated but pretty amazing.