How this works
Why a Charter Quote Expires
Somebody used to booking hotels finds this the strangest thing about charter. The explanation is simple and it is the reason this whole site is arranged the way it is.
A quote is a stack of answers with different lives
Nine things sit under a charter price. Three of them are true for hours, three hold until the trip changes, and three never change at all.
A quote is only as durable as its shortest lived part. Two of the three perishable answers, where the aircraft is standing and whether it is free, move by the hour, so the whole number moves with them.

What is not expiring
The runway does not shrink. The field does not stop clearing customs. The party does not get bigger by itself. Those parts of the quote are as good next month as today, which is why the desk asks them once and keeps them.
What expires is the part that belongs to somebody else's fleet on somebody else's morning.
Why this desk timestamps instead of hedging
Every quote carries the date and time it was assembled and says plainly that availability was true then. That is more useful than a vague warning, because it tells a reader exactly how much weight the number will carry.
A quote with no timestamp asks a reader to guess, and readers guess generously.
What to do with an expired quote
Ask again. That is the whole answer and it costs nothing here. What comes back is a fresh answer rather than a renewal of the old one, and it may be better: an operator badly placed last week may be sitting at your field this week.