View Full Version : Slot time question
Check 6
28th Jul 2000, 12:25
This is a question as to why a slot time is assigned, but while en route, there is little air traffic along that route, both visually and also based on how quiet the radio is. A specific example was on 26 July from Rota (LERT) to Sigonella (LICZ). The routing was to Alicante (ALT) then splitting the Med. Sea over Mallorca. Do any of you controllers have any idea why this happens? Any suggestions? Thank you for your help.
Check 6
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Kick the tires, light the fires, first off is lead, brief on guard.
Numpo-Nigit
28th Jul 2000, 21:33
Whilst I obviously cannot comment on the specific route mentioned (it's a little too far south of my sectors), there can be many reasons for the annoying apparent lack of traffic after a slot delay. Slots can be issued for various reasons, not just en-route congestion. There may be too much traffic for a particular destination's runway or apron capacity, or military activity may have reduced the levels available to civil ATC. In some cases your route may be crossing a very busy route, and "your" controller retains you on his quieter frequency, having co-ordinated you through the busier sector - then you won't hear much and, if we get it right, you won't see much either. This is not an exhaustive list, just an indication of some of the many factors involved - we don't delay aircraft with slot times just for fun!!!
Slots are often allocated unnecessarily when operators file "yo-yo" flight plans (anticipating delays on a particular route); this obviously leads to a greater number of flight plans being in the IFPS system than flights actually taking place. This practice is not actually against any rules, several operators seem to have stopped doing it following requests from area centres.
Plus the hundred-or-so other reaons of course......
Smoketrails
29th Jul 2000, 03:22
I agree with NN and 1261. However, the truth is also that the flow control system just isn't optimal (yet). Despite everything our unit still manages to get sector overloads one moment and bu**er all happening the next! It's frustrating for us too. We often see bunching over a particular RP followed by gaps of 10 to 15 minutes with almost zero tfc over that same RP. It's almost impossible to get an even spread on all sectors at all times. Multiply that by all ATC units serving Europe and you can see how compounded the problem becomes. The CFMU is striving to improve all the time but it ain't going to happen tomorrow.
[This message has been edited by Smoketrails (edited 28 July 2000).]
Findo
29th Jul 2000, 16:43
Check 6 - the simple answer is that somewhere on your route and ATC sector or airport had more aircraft planned than it could safely handle. The sector capacities are all published. You probably have no idea of where that sector was but your company ( USN ?? ) should have known by the slot message that was issued. That information is available to all companies. It would identify the reason for the slot ie a sector capacity or a capacity reduced because of weather.
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Go with the flow ... or you'll miss your slot.
Check 6
29th Jul 2000, 18:12
Thank you all very much for your feedback. USN - yes. The only other question/comment I could add is that I typically file my flightplans 48+ hours (approx.) in advance. I have been told that this sometimes can eliminate a slot, due to first come, first served. Does this make a difference? I appreciate the work ATC does in Europe. Cheers, Check 6.
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Kick the tires, light the fires, first off is lead, brief on guard.
Findo
30th Jul 2000, 23:38
No because when flow control is imposed it will allocate slots to all aircraft entering that airspace during the period flow control is necessary. Slots will only be issued at the time flow is imposed. If you have filed 3 to 4 hours you will be in the queue with everyone else.
48 hours in advance is only likely to mean the plan gets lost !!
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Go with the flow ... or you'll miss your slot.
Check 6
31st Jul 2000, 10:32
Thank you all for the responses. This helps me have a better insight into slots.
Cheers, Check 6
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Kick the tires, light the fires, first off is lead, brief on guard.
Good to hear that Seville ACC have at last got the hang of "DOF" in item 18 on FPLs. I lost count of the number of times I had to re-file because their computer had deleted the FPL at midnight the day before. Then again, maybe it was political, it only happened to Military FPLs in or out of Gibraltar.
Stay Frosty,
LXGB.
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