I am running a Dark Fantasy Basic sandbox/hexcrawl campaign for several sessions now. I'm using DCC and LotFP adventures, monsters from OSE and AD&D... it is a bit of a mess. At the same time, I've been reading the original DMG and looking for ideas to apply to my own DFB / B/X campaign.
Last night, the PCs went exploring the wilderness and ran into a small pack of griffons. I imagined they would do some kind of "swooping attack" like a bird, but I had no rules for that (either in DFB or B/X, as far as I could remember)... so I made some rulings, and took inspiration from the DMG, 5e (the owl has a "flyby" attack) and even 4e!
This was my ruling: the griffon would attack only with its claws, without landing. If you win initiative, you can attack first... IF the griffon is attacking you specifically. Otherwise, you had to use ranged weapons.
[Fun fact: the 2e MM mentions these tactics but not any actual mechanics for that AFAICR].
I got hand-wavy with "actions": yes, you can trade a bow for a sword without affecting your attacks, as the griffons fly over you to attack again. One minute rounds can justify lots of stuff...
And then I used an idea from the DMG: winged creatures cannot fly at less than half HP (which 4e call "bloodied" and uses for multiple monster actions) since their wings are probably hurt. There could be other useful rules in the DMG I ignored... let me know if you remember anything.
Eventually, the PCs got together with their hirelings in a tight pack so any could attack a griffon with their magic swords.
The griffons landed after a while... and then they got to use their claws AND bite, becoming more dangerous (but more vulnerable). Notice that if they had been protecting their nests they'd probably just stand and fight.
It was a fun fight, bigger than the sum of its parts. Just thought I'd share this with you.
It is good to have a favorite version of D&D or, even better, create your own. But I'm also glad to mix bits and pieces, even from editions I don't like or play anymore. And to come up with my own stuff.
In conclusion, I don't think I'll be able to play anything RAW anytime soon...
UPDATE: turns out this is already in the rules, as pointed out in the comments (X27):
Swoop: This is a diving attack, used by certain flying monsters. If the flier has surprise the swoop attack does double damage. Swoop attacks cannot be attempted against opponents hidden by dense forest or jungle cover. In addition, on a roll of 18+, the creature has grasped the victim and will try to fly away. If the character is too heavy, the monster will release him or her and attack normally the next round.
B/X doesn't see to specific which attacks (should we include bite?), nor does it mention swooping for griffons or giant hawks (only for rocs), but this is covered if you check the 2e MM as suggested above. Still, it doesn't quite answer the question "can you attack a flying griffon?", AFAICT... so maybe there is some point to my ruling.
So, I guess the rules are there, if you look for them... My bad. At least my instincts (or memory) made some sense during the session.