Originally Posted by AICUS
CTOT = Calculated Take-Off Time
the 'Slot' is 5 minutes before and 10 minutes after the CTOT. Therefore if you have a slot the earliest airborne time is five minutes before and latest ten minutes after.
Not quite. The -5/+10 is there FOR AIR TRAFFIC CONTROL ONLY. It's a buffer to allow for final sequence changes.
True, the CTOT is the calculated take off time - i.e. the time the flight is expected airborne.
The CTOT IS the slot - there's no difference, just terminology.
If you want I can send you a WHOLE lot more on CTOTs and how they're worked out and all sorts of other stuff.
As for flight plans - they're active once filed, they become LIVE at EOBT minus 20 hours, they are ACTIVATED by a mechanism called FIRST SYSTEM ACTIVATION or FSA, they expire according to a somewhat complex procedure (which also encompasses AIRCRAFT OVERDUE action), if you don't FSA a flight plan it becomes suspended.
In a nutshell, any change to a flight plan departure time of more than 15 minutes should be notified to IFPS Brussels (because it could mean the difference between a slot or no slot, on time or otherwise).
Again, it's a complex algorithm; I can elaborate if you let me know?
SATCO