Slot Error.

[Carnacalla]

Last night before sleeping I had bought a used aircraft off the market and set up routes for it, but I was having it delivered to the wrong airport. Woke up this morning and ferried it to the right airport and scheduled the routes, which had just got a slot warning but they were still in place. So both the routes ran for 2 game days with passengers, but I just got a message today (game day) stating that the slots were removed on the route, and I just had to repurchase them.

Disgraceful, I am already short of money and I dont need slots being removed for no reason. I had suspected errors before but today is the first day I have seen that there is an error without any reasonable doubt.

[wildavidson]

Its not an error - when you set up a route will a full weeks schedule (1234567) and you are getting slot warning mails you need to fly all slots assigned to the route until the slots are classed as being flown and the warnings go away. In your case as you only scheduled the routes and flew them 2 days before the deadline, the slots are correctly taken away.

Best thing to do is to make the routes up but don't buy slots until added to your aircraft and if you have already done so and the intended aircraft has been sent to the wrong base the best thing to do is to move one of your existing schedules from a plane already operating and using the newly available plane, rebase it and set your schedules from there as if you do that you wont lose the slots.

[Kadachiman]

From theManual

Airport slots are a valuable asset for your airline, although they cannot be traded. At crowded airports slots may be the thing that decide which airline can actually operate to that airport - a new airline cannot start operations if he cannot get the slots.
The airport slot system operates with a simple use-or-lose principle. Each slot you own must be actively used or otherwise it is removed. If you are in the danger of losing some slots you will first get a warning to your game message box about this and if you do not react on it the slots will be removed. There is no monetary penalty for losing the slots. Aircraft maintenance does not lead to losing the slots. The amount of inactive days for each slot before removal depends on various factors but is usually about two game weeks.

As the previous poster has stated it appears that you had a MTWTFSS schedule and only manged to fly a few of the days but not all of the days of the schedule before the slots were due to expire
Used aircraft take 2 weeks to deliver, therefore setting up schedules with slots at the same time as ordering the aircraft is a very risky strategy that will generally see you losing the slots