@CT
I'd say fuel for the Zep isn't that much of an issue, it'll have fuel cells and a recharging battery for more or less continuous (slow) flight. It's a big gas bag though so not that bullet resistant! Visibilty as mentioned is poor and getting worse...treat as light smoke around the convoy going to heavy about 100m out and max normal visibility is probably 200m. Thermal is a bit screwy too because of the ash (although my physics might be a bit dubious on that one so feel free to set me straight if that sounds like bollocks!)
Any breeze? Right now I'm seeing a -3 penalty without range penalties due to Thermographic Vision, although not sure about the ash. To me, ash is fairly cool, it's main problem is that is clogs the air space and makes it hard to breath. It's mainly a matter of where the ash comes from. If it's just falling from the upper atmosphere, it's about the same temperature as the atmosphere (just a bit of quick research, may not be 100% true all the time). Still thinking that being up in the zeppelin is bad idea if it gets shot up and literally explodes while I'm next to it.
On the Low-light and Thermographic Vision argument, I always thought of them as two separate types of vision that you had to switch between. Like, you could have low-light all the time, but when you want to see in the infrared spectrum you had to conciously switch to it.
Kind of fun seeing Torrent's response. Boy did I get backhanded, and Ghost knows it. Still wouldn't have played that any other way; I'm not gonna do something that my character would never do simply to metagame.
I'll have an IC post up soon.