.... And don't have the cash available on delivery?
Thanks! :-[
You go into debt (cash becomes negative). This is not a problem if you are only a little in debt compared to how much money you are making and are able to pay it back quickly. It is a problem if it takes you a while and you start missing plane maintenance, are not able to renew leases, etc. The game will also give you a bankruptcy warning, but it takes about a week real time to be forced into bankruptcy.