View Full Version : CTOT's, SLOTS, & FLIGHTPLAN EXPIRY...

11th Jun 2006, 20:00
Hi guys, been asking around a few of the guys where I work, and have managed to confuse myself completely about what all the above, basically if someone can explain all of the above and their implications on everyday affairs I would be most grateful



11th Jun 2006, 21:04
CTOT = Calculated Take-Off Time

For the purposes of airports, en-route traffic management and arrival at the other end this gives everyone a chance to regeulate the flow of traffic to keep things manageable (in theory).

as i understand it, 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. If you get to the holding point early they will leave you there and if you are looking for push/taxi close to the slot they may tell you that it is too late and you need to apply for another slot.

As far as flight plan expiry...can't remember all i know it's happened to me a few times:{

Hope that helps

11th Jun 2006, 21:18
I think Flight Plans are 15 before to 30 after filed dep time?

Standard Noise
11th Jun 2006, 22:59
Depends what you mean by 'expiry'.
The way we have to work it, is that once the clock ticks past EOBT+15, your plan must be delayed before you can start, this may or may not bring up a slot. Marvellous, oh, and we hate it too, pain in the a**e!

11th Jun 2006, 23:50
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?


Check Airman
13th Jun 2006, 21:31
yes. please expand if possible. always good to know what atc is thinking...

13th Jun 2006, 21:55
The -5 +10 mins seems to be a bone of contention with some ATC units.

I know its for their use but any mention of airborne at -5 mins gets the old its for us not you lecture. Ok but but it takes 2 to tango. If we don't have our engine's running checks complete and ready for departure neither of us can use this bonus in the system.

A reply of "rodger be ready to taxi x mins before slot" would be alot more helpful than a lecture how how its for ATC use not the pilots. It would be very handy for us as well, especially for us as well when operating out of airports which we are "strangers" to. And the ATCO has a clue on the likely traffic loads at the time and when THEY need the aircraft ready for. It would also let us have a clue when we need to refile if we won't make the taxi time required.

And save the lectures for people that deserve them getting stroppy at the holding point.

BTW EGCC seem to have it sussed when it comes to this sort of thing. I have never heard a lecture on freq and Clearance give's all the details required for an effecient use of time and tarmac. If you call them they will always give you the heads up.

It would be easier for the local airport to issue a ready for taxi time instead of getting into debates with this -5 plus 10 mins stuff. Let the ATCO's deal with what they are good at, shifting tin and pilots do what they are good at getting the aircraft ready for a certain time point. If they can't they will tell you, if they can they will do it.

13th Jun 2006, 23:03
Try CFMU Handbook (http://www.cfmu.eurocontrol.be/cfmu/gallery/content/public/userdocs/docs/handbook_systems_8.pdf) and IFPS Handbook (http://www.cfmu.eurocontrol.be/cfmu/gallery/content/public/userdocs/docs/handbook_ifps_11_v2.pdf)

14th Jun 2006, 13:45
May I assure you there's no lecturing involved with my post. And I'm mindful of the pilot's point of view. But as with so many other things, if we don't all play the game together we aren't going to get very far. -5 and +10 are tight enough buffers as it is; there won't BE that leeway in a couple of years when the slot time MEANS the slot time, with no -5/+10 or anything else. (Last I heard, it'd due to come down to -2/+5; the timing I'll have to investigate).

15th Jun 2006, 22:05
Sorry I hadn't taken it as a lecture.

The The -5/+10 is there FOR AIR TRAFFIC CONTROL ONLY

It seems to be a very jealously guarded right for ATC. And I must admit I can see that this reaction must be because of the minority of pilots taking the piss and getting stroppy on the RT because they haven't got the desired -5 on the slot.

if we don't all play the game together we aren't going to get very far

Sums it up quite nicely the way I understand it. Same with taking the piss by asking for start 5 mins before the is slot about to finish and you still have to taxi for miles. And I hope the tone of my post conveyed team work and nothing else.