While we pretty much assume normal tripping fails on flyers what about using Ki throw would that allow someone to get a flyer onto the Ground?
Both RAW and RAGM would be nice but specify which your talking about.
I don't mean to throw a monkey wrench into the works but my group has always played with the 3.5 stall rules which allowed you to trip only fliers with wings. So, I'm not really playing devil's advocate here so much as saying that I don't know if it is even safe to assume that you can't trip any fliers.
Either way, Ki Throw should do it.
Beholders? Gelatinous cubes? What effect does tripping
have on these creatures? Can a prone character be tripped
again? What about flying and swimming creatures? Many
creatures have neither legs nor any relationship to the
ground or gravity. How does tripping affect them?
Anything using limbs for locomotion can be tripped.
Things that don’t need limbs for locomotion can’t be tripped.
You can’t trip a snake, a beholder, or a gelatinous cube. You
won’t find this in the rules, but then it really doesn’t need to be
in there—the rules can leave some things to the DM’s common
sense.
A creature flying with wings can be “tripped,” in which
case the creature stalls (see Tactical Aerial Movement on page
20 of the DMG). You can’t make an incorporeal creature fall
down. You also can’t trip a prone creature.
Creatures can’t be tripped when they’re swimming (the
water holds them up). Likewise, a burrowing creature is driving
its body through a fairly solid medium that serves to hold it up.