In case you were wondering, air traffic is a concern in Lake Erie City. There's not a ton of people who can fly but there is a not insubstantial amount of them, which is something to expect in a metro area of over 10 million. For the most part, civilians aren't allowed to fly above 200 feet. Some do anyway. It's not really a law that can be enforced all that easily. But most abide by the law. If only because it's safer and leaves emergency lanes clear.
That brings us to law enforcement and licensed superheroes. They're cleared for up the height of the tallest building in the city for the purpose of rescue and patrols They can be allowed to go higher should the need arise. But the general rule is don't go higher than Cape Tower.
But that still leaves the matter of avoiding collisions. There are speed limits but most of the laws are common sense. Like looking where you're going, no distracted flying, and signal when able. Also don't fly where planes are. That's a big one, but you shouldn't be surprised that more than a few people have ignored it.
Both Evey and Izzy are breaking the law right now. But I don't think that's the foremost issue on their minds right now.