This section of the rules outlines the basics of aerial movement to assist the GM with flying monsters and movement on flying mounts or otherwise in the air. Flying creatures gain altitude at half their movement rate and dive at a 45° angle, descending 1-ft for every 1-ft of forward movement. Creatures with aerial agility level VI are not subject to these two restrictions (see below). Diving attacks over 30-ft grant a double damage bonus vs non-diving targets, including ground targets. Attacking while climbing incurs no damage or attack penalty. The GM may wish to consider an operational flying ceiling of 5,000-ft above sea level, the upper limit of breathable air without special means on Earth, though a campaign world might be quite different.
Apart from aerial agility level I, the lower level classification of fliers are generally larger, more massive creatures. Lighter and smaller creatures tend to be classed in the higher levels.
Except for very large creatures, such as dragons, riding a flying monster reduces its aerial agility by one step.
The levels enumerated below represent stops along a spectrum of ability, so the GM may assume a small amount of variance within each level. Turning capacity assumes full movement rate; creatures moving at half-speed turn as one class higher. Level II, III, and IV creatures must be moving at least half-speed to remain airborne.
Level I: Barely a flying creature, these creatures float on the air, allowing the wind currents to carry them from location to location. These creatures can sometimes slightly alter their direction of travel or move at very slow speeds, but otherwise manoeuvre like a hot air balloon (e.g. //levitate// spell). This category also includes gliding creatures, such as flying squirrels or flying fish, that travel through the air but do not truly fly.
Level II: Creature requires 5 rounds to reach full aerial movement rate and can turn 30° per round (e.g. dragon).
Level III: Creature can reach full aerial movement rate in 2 rounds and can turn 60° in one round (e.g. sphinx).
Level IV: Average agility. Flying creatures of this type reach full airspeed in 1 round and can turn 90° per round (e.g. flying carpet, giant bat).
Level V: Full airspeed is reached in 6 segments and the flier can turn 120° per round. These creatures can also come to a complete stop in 6 segments and are capable of hovering in place (e.g. //fly// spell, mephit).
Level VI: These are creatures born to fly, taking to the air as naturally as a human walks on the ground. Such fliers can reach full speed or complete stop in 1 segment, and can hover. Level VI fliers can easily reverse course in flight, gracefully executing turns of 180°. A Level VI flier has nearly complete control over their movement in the air (e.g. genie, air elemental).