Need ideas on restricting flying in a fantasy world

[Varyon]

I'd go with having highly unpredictable magical "currents" once you get high enough. On the ground, it's easy to predict how magic is going to move around, but up in the air you can easily hit a small patch of Very High Mana, causing you to suddenly zip out of control - or No Mana, resulting in your flight stopping and a long drop. If there are flying creatures that rely on magic (like dragons), they would likely have the ability to notice (and possibly make use of) such "magic thermals," and avoid the patches of No Mana.

[Sunrunners_Fire]

Originally Posted by tantric

I'm one of those guys who likes to have a fairly rational explanation to give my players, and I'm having a hard time with restricting flying. Possibly magic comes from the Tree and its roots, and thus the farther you get from the ground, the less functional it is? Any other thoughts?

Flag the energy/fatigue cost of the magical flight (and other things you wish to permit but severely restrict the usage of) as Hazard: Missed Sleep.

[Joe]

Originally Posted by tantric

The idea of limiting flight speed is pretty brilliant. If you can't fly faster than a bird, global (diskal?) society is limited.

One thought for you, in case it helps: watch out for bird-speed flight! Many birds travel long distances much faster and much more easily than medieval people did. Realistically playing out the consequences of this can spoil a psuedo-medieval setting pretty quickly.

I had this trouble in an Ars Magica campaign once.

One of the characters could shapechange into a migratory bird. Suddenly fast long distance communication was fairly simple, and the borders of the setting could be crossed quite easily. To preserve the feel of the setting, the player had to start coming up with all sort of implausible reasons not to fly off and solve the mysteries of the Frozen North, the Hot South, and the Mysterious Orient...

[Otaku]

Emphasizing the dangers (or at least complexity) of flight can do wonders... especially once you add in the magical fantasy aspects. Magical travel tends to ignore these things in many settings, so discouraging magical flight may just be a matter of not glossing over the details. No one wants to attract a large, flying predator... and who wants to have their great mage die because he collided with a flock of birds at high speeds in midair?

If you really want a reason for not allowing such magical flight... make it obvious by having it be via intervention. Be it divine ([insert god/] claiming the skies for himself) or mundane like government (it is a threat to a monarch's sovereignty) or something else (merchant's guild protecting their trade, powerful wizards denying access to the majority, etc.).