It is a precondition for air travel without additional
actions that one be clothed, holds(clothed(traveller),s), that one
not be lame 
,
and 
,
etc. With a bow towards later explaining how to make this happen
using formalized contexts ([McCarthy 1989] (McCarthy 1991,1992)
we'll abbreviate the above to the
propositional fluents clothed, 
and 
.
In one respect these conditions are similar to the condition
that one have a ticket. However, one is willing to specify as
part of the formalization of air travel that one have a ticket,
but it is not reasonable to refer explicitly to these other
conditions.
Here's an approach to doing it. The simplest approach
would be to have a fluent ab7(traveller), abbreviated ab7,
and have sentences 
, etc. We then
use 
as a precondition for flying. We then circumscribe
ab7. This doesn't work well enough for two reasons. First
we still have to mention all these other conditions in the
circumscription and circumscribe them also. Second, suppose
one of the conditions fails, e.g. the traveller is lame so a
wheelchair must be provided. Then we lose , and
we haven't got rid of the other conditions.
At present I think the first problem has to be solved by some form of present resembling the scope of [Etherington et al. 1991]. If we circumscribe it, we are jumping to the conclusion that the interfering phenomena aren't present The second problem may perhaps be solved by introducing a parameter exceptions to ab7 and requiring that none of the exceptions be unresolved.
Both of these ideas require details.