Tripping winged creatures

[Dragon Mage]

I know I read somewhere the rules for tripping creatures that are flying with wings. Can someone tell me what they are or where I can find them?

Thanks

 

[rvalle]

And would the rules be the same for someone with a Fly spell up?

rv

 

[Sektat]

You find those rules here:

http://www.wizards.com/default.asp?x=dnd/arch/rg

in the "all about movement" sections.