Fly speed, Vision and visibility

[benbash]

How do perception visibility conditions affect flight speed?

As a specific example of what I mean,
An Adult Green Dragon has has Fly speed of 200 ft. (poor)

Dragons have darkvision 120 ft. and blindsense 60 ft. They see four times as well as a human in dim light and twice as well in normal light.

Outside on an cloudy, moonless night ("Darkness" according to the CR), with no other light source,
is the dragon's top speed limited to 120 ft /round (same as the darkvision range?)

What about in a massive fog effect where all vision (including darkvision) is limited to 5 feet? Does the dragon's blindsense ability of 60 ft limit the Fly speed to 60 feet/ round?

What do other Game Masters do here?

Thanks!

[evolved]

Considering that the point of origin of sight moves as a creature does, I don't see why it would reduce their speed. A human in a dungeon with a torch could run at full speed, no?

[Kayerloth]

The only problem is one of real world issues and physics ... planes flying into mountains despite radar/instruments or folks running into a deer crossing the road at night (aka overdriving your headlights). You not only have to see the object you have to have enough time to react to avoid hitting the object. A dragon flying fast in heavy fog might very well crash into a tree line, a barn or whatever simply because while he can see it with his blindsight he can't react, particularly with Fly (poor), well enough or fast enough to avoid it. Folks driving most definitely smash into each other in heavy fog because they drive too fast for the circumstances. Someone running in a dungeon with a torch might have more trouble avoiding tripping over something but generally isn't going to move so fast he'll run into a wall before he could stop, doing so when your vision is down to 5 feet or so is another matter.

Now whether you worry about that is up to the GM and his group. A dragon might not worry much about running into the upper reaches of a tree or even a barn ... the castle wall or a mountainside, however, is pretty darn solid. Guess it depends how much you've pissed him off :D

[DeltaOneG]

Mind you, planes and cars are moving mighty fast.

Unless they are using a method of movement that restricts turning (charging, running, etc) then sight should not limit movement. The fly skill has rules to help determine if a flying dragon can avoid large object in the way and ground movement allows you to turn/stop as soon as something gets in the way.

Generally speaking, 120 ft of vision gives you plenty of time to react to new objects. 60ft may cause problems, but only if your fly skill isn't good enough.