Are there established rules about gliding? How far can I glide? What is my Speed while gliding? How much altitude do I lose per second while gliding?
3 Answers
Gliding is not a thing in 5e
And in fact, Gliding is just a form of flying (just with less effort). Colloquially, we envision gliding to not take movement, but in 5e Movement is simplified and generalized to mean distance traveled. From the Basic Rules:
Your speed determines how far you can move when traveling (“Adventuring”) and fighting (“Combat”)
Your fly speed as an Aarokocra is 50, so any time spent "gliding" would still use up that 50 fly speed.
Flying is falling and missing the ground
When Flying, you've basically got a choice between flying with movement, hovering (if you can), and falling. Gliding isn't an option, so it must fall within one of those possibilities and you probably don't want to be falling.
Flying creatures enjoy many benefits of mobility, but they must also deal with the danger of falling. If a flying creature is knocked prone, has its speed reduced to 0, or is otherwise deprived of the ability to move, the creature falls, unless it has the ability to hover or it is being held aloft by magic, such as by the fly spell.
If falling, you can reference this question for information on that.
There are no rules for gliding.
Creatures either have flying movement, or they do not. The only variation is the ability to hover, which just determines whether or not the creature will fall when unable to control their movement.
Flying creatures enjoy many benefits of mobility, but they must also deal with the danger of falling. If a flying creature is knocked prone, has its speed reduced to 0, or is otherwise deprived of the ability to move, the creature falls, unless it has the ability to hover or it is being held aloft by magic, such as by the fly spell.
In the real world, gliding may not require propulsion, but it is most definitely movement.
Interestingly, the only ability where the word "glide" seems to appear is in the Earth Glide ability of certain elemental creatures.
There are no specific rules on gliding.
Your fly speed already factors in all means of flight, including gliding.