Prevailing winds would need to be taken into account (location and time of year). The actual range could be significantly more or less when this is taken into account. Strong enough winds in the wrong direction could stop the airships cold (or force them to move to altitudes where the wind conditions are different. Strong enough winds in the right direction could make the entire process much, much easier (just floating along in the currents like a raft heading down stream.
Just a thought.
__________________
 "It is better to be feared than loved" - Nicolo Machiavelli
|