First, welcome to the boards!
Second, way to start off with something nice & easy!


Things to remember about air battles:
- They are in 3 dimensions. Aerial attackers- especially those who are trained or are naturals- will be attacking from unexpected angles, including from beneath. This is because "landlubbers" tend to think in 2D. Even if they remember to look up, they may not look down...or vice versa...so use ALL of the angles on them. Classic film examples include Wrath of Khan and Dragonslayer.
- Falls can be fatal. If you don't want a botched roll to send a PC tumbling to certain death, have some kind of failsafe. Perhaps the airship has safety lines that attach to a harness for anyone involved in combat. Or perhaps the attackers have nets to catch the falling.
- Don't disarm the PCs unless its for a story-arc reason. While not fatal, dropping things can turn the tide of battle in an instant. Because of this, you might want to avoid using "fumble" results or NPCs who "disarm" since dropped items may not be recoverable.
In addition, you may find minis and/or wargames to be quite helpful for helping you depict the combat. Games like
Sky Galleons of Mars or
Crimson Skies have minis and/or rules that may help your players visualize what's going on.