Slot Question

[Critical Mach#]

I had an EOBT for 1500z, with no slot assigned. Requested clearance and start at 1455z and... so far so good.
Pushed back and requested taxi clearance...all ok. Taxi to holding point and transfer to TWR. As we became number one we were instructed to moved aside and give way to two more traffics. Out of curiosity I asked for the reason ( I figured someone with a tight slot) and was told that while we were taxing to the active rwy, Clearence Delivery informed twr that a slot just came in for us and that we had to be held to meet slot.

My question... Flow control can issue a slot to an aircraft that already has its clearance and is on its way to the holding point?.

TX
CM

[vintage ATCO]

I have known it happen, albeit rarely. We would normally ring the Flow Manager and ask why and to see if there was any leeway. However, I see you were somewhere posh with clearance delivery . . . .

[almost professional]

normal procedure for our unit, which I have had confirmed verbally by flow is that if A/C has pushed/taxying when a slot is issued then you disregard the slot

[5milesbaby]

You may have been subject to a departure interval suddenly imposed by En-Route. Normally the flow off Heathrow say is 1 a/c every 2 minutes on the same route, speed dependant. There are a few hours in the morning and evening where this increases to 1 in 3, and sometimes during heavy traffic En-Route will impose 1 in 5 without warning due to high demand. Then I would expect you to have to move aside and let some through.

[055166k]

Tactical Decision

Occassionally an airway sector can experience a short duration burst of traffic which may result in a request to an airfield to hold a couple of departures for a few minutes. The request may be with little warning and is not the fault of the airfield. There may be an ultimate benefit to the traffic concerned, instead of level capping at an uneconomic cruising level, a gap of 2 or 3 minutes may be all that is required to ensure a better en-route profile......additionally there may be other reasons which are not readily transparent to either the airfield or the traffic on the ground. In the instance you report it is quite possible that the airway sector had agreed not to impose flow at all, to the benefit of the overall traffic situation....in other words agreeing to short duration overloads to keep delays to a minimum....but reserving the right to impose short-term tactical measures as and when necessary in the interest of safety and service provision.

[Point Seven]

The point about MDIs (Minimum Departure Intervals) is quite correct but you probably didn't have one imposed on you or that is what the Tower Controller would have told you.

Stupid as it seems, CFMU slots often come through when planes are at the holding point. My own personal method to deal with it is selective deafness when I'm told.

And are there really aerodromes WITHOUT clearance delivery? How quaint.

P7

[The Highlander]

If your slot came from CFMU then a quick call to your ops and get them to speak to them. CFMU cannot issue a slot to an aircraft at the hold. I have successfully negated many such occurences by stating that you are at the hold. |The helpdesk operators generally do something to exclude your flight from the regulation. Not very jnice for other operators i know, but if we have to obey the rules then so do the CFMU.
Hope this helps for any future occurences.

Rgds
Highlander

[Critical Mach#]

Tx for the answers...

I talked to the twr ATCO and the clearance guys the next day after I posted my message and they both agreed that they shouldn´t have passed the slot onto us and that CFMU should have been imformed that the aircraft was already out of the gate and in the holding point with a request from their part to disregard the slot under those circunstances.

Again, tx for the answers.
CM