Thanks for all the replies, guys!
"How does the standard adventuring group cope with this scenario?"
Ranged attacks.
D'oh!
Without reading the creature before answering the post I would say that you should probably ignore the shift before and after attack part of the basic bite attack when using the flyby attack (though I suppose strict interpretation of the rules would allow you to do it).
But I would imagine that any PC group would be able to land a status effect on the dragon that would stop or reduce its aerial antics.
Any immobilise or stun effect would bring the creature down, also a sky rending bow (if memory serves) would stop all that flying. There is also the possibility that readied actions could be used to act when the dragon comes into range...... etc etc.
EDIT:
having read the creature for myself I would now say that it should indeed shift before and after the basic bite attack during the flyby attack. It certainly is a mobile little bugger! (which fits its skirmisher type)
Its nice to see a dragon that at least stands a chance at being able to live up to its reputation!
Yeah, this is what I thought as well, cool to have a REAL flying dragon for once. And for the record, I'm not convinced that immobilizing a flying creature (that has hover) causes it to fall, but...
Note that tripping a flyer brings it out of the sky too.
...knocking it prone does on the other hand. Which makes for quite a funny mental image!
Which is usually good to acceptable for half the party. One of 4e's designs is your character is set
strongly into a niche by their available powers. For a character without access to many, if any

powers, a solo or even elite playing keep away is going to take a long time to whittle down because it's the characters Powers that add the lion's share of effectiveness to attacks.
While 3e had issues along these lines, those were usually
far more with player control to counteract.
But it still depends on the terrain. If the party has the option, they can retreat to a more defensible position and wait for a better time to fight. Of course, there're also potential plot considerations as they might not have this option if the encounter occurs just outside of town and the heroes have to defend the town.
My players, even at level 4, have a wide variety of immobilize, knock prone, and forced movement powers. This is where the controller (and defender) classes should shine... either imposing movement restriction on the skirmisher, or placing damaging zones to try to convince the skirmisher to stay put.
Failing that, there is always readied actions.
The problem is that the bite is reach 2, so the only thing you're likely to get it with is a readied charge, which is a basic attack effectively.
It looks like this is a monster that you only use if your players are likely to have fun against it: which means either your players have lots of ranged powers that can ground and restrain a foe, or you cripple it with adverse terrain. Otherwise it's going to end up as round after round of "the ranged characters fire/ready a shot for when it's in range, and the melee characters ready a charge".
That said, maybe this is a problem with flying monsters in general? Even if you do hit a foe with something that grounds it, typically it's only grounded for a round. Maybe taking flight needs to be more difficult to do once grounded?
I guess I better give you the lowdown on the encounter I was planning. The party (5th level, going on 6th after this encounter) consists of an elven beastmaster ranger (with a little ranged capability), a genasi trickster rogue (throwing dagger/shuriken), a half-elf bravura warlord (dilettante: cutting words, but can you pull a flying creature?) and an eladrin illusionist wizard (phantom chasm, grasp of the grave). Two members of their party, a goliath earthstrength warden and a human artificer, are not present. Thus they lack a defender, eeek!
The party are on a covert hunt after a group of kenku assassins, and have just reached the city of the kenkus base of operations when they are spotted. The kenkus, alarmed at the adventurers rapid and secret approach have organized a haphazard ambush along an old cliff-road near their nest, hoping to take care of the pursuers once and for all at the risk of losing everything.
The kenku have set up boulder-traps and rock-slides from a higher ledge that they trigger at the PC's arrival, trapping them on the road below while raining death from above. The encounter should be moderately difficult, considering the PC's have nearly all of their resources available to them (some loss of healing surges due to the arduous journey etc.).
The party shouldn't get to arrogant though, as the leader of the flock, a young copper dragon, joins the battle some rounds later with a wave of kenku reinforcements (minions). The boulders and debris on the road can provide some cover, but the mobility of the dragon will be difficult to counter.
A couple of design note's:
- The road is relatively broad, but a it is flanked by a roaring river below and a crumbling cliffside above, so it should offer a sense of both open and closed terrain.
- Since they are lacking party members and a defender, I think I'll introduce a
seemingly benevolent NPC that fights at their side. I actually came up with an interesting concept (swordmage/warlock hybrid) that I could slip in. I might even give him a flying mount, perhaps a hippogriff?
- The real gamebreaker here is how fast the party go through their resources, especially dailys. There will be some form of Perception checks to notice the approaching creature. I'll probably set the dragons arrival as a milestone, granting them an action point and refreshing their second winds at the same time. I honestly don't want to slaughter the PC's!
- The terrain should preferably be disadvantageous to the PC's at first, but be more helpful as the battle continues and changes dynamically (reflecting the unpreparedness of the kenku and a lack of communication with the dragon). Perhaps a ballista on a higher ledge, which can be used to take down the dragon?
- I'm actually adjusting the dragon to present a greater threat, putting it somewhere between young and adult in terms of power, and adding abilities that sync with the kenku. Secretly I don't want to kill the dragon so I'll have it broker a truce at 1/4 hp, and supply the characters with the information they need in exchange for it's life. Hopefully at least one of the PC's are standing at this point!
What do you think?