New Format Lhr Arrival Instructions?

[G3LMO]

Why is Swanwick giving inbound trans oceanic aircraft from overhead Cork (towards Strumble VOR on 129.375MHz initial London contact frequency), an arrival instruction of:

"Cleared direct NUMPO, BEDEK, for OCKHAM 2F arrival".

When it is quite apparent many times that they will NOT be completing an OCKHAM 2F arrival at all, but turned NE (080 deg) from BEDEK to hold North of LHR.

Surely it would be more appropriate to leave until on 133.6 MHz east of NUMPO just before starting descent to the usual FL140, for the onward clearance to be more positive and therefore less possibility of being 'confusing'?

[The Fat Controller]

You HAVE to give them something in case of radio failure and that is probably what they have flight planned to do.
Whatever happens subsequently cancels the previous clearance.

[Cartman's Twin]

The above is correct and it does provide RT Fail clearance limits. A significant majority of the aircraft on this route complete the OCK arrival and it is only when the OCK hold becomes full that a 'stack swap' is considered. (There are alternatives such as holding en route (at Malby) or bringing the a/c in at a higher than normal level.

The initial clearance is given well in advance and as the aircraft holding for EGLL are varying continuously it is sometimes quite late (after Bristol) that it becomes apparent that a plan B is required.

Hence all a/c are given their expected STAR and if this is changed, the new arrival route will be given as soon as possible.

Hope this helps

Cart

[Scuzi]

Also, stack swaps from OCK to BNN are usually initiated after the aircraft have passed STU, sometimes by quite a bit.

If you are overhead Cork then it won't be apparent if you will be required to move north to BNN. It may be apparent that one or two aircraft *might* be required to move but the particular aircraft cannot be chosen until they are much closer in.

Hope that makes sense.

[anotherthing]

G3LMO


When it is quite apparent many times that they will NOT be completing an OCKHAM 2F arrival at all, but turned NE (080 deg) from BEDEK to hold North of LHR.


a bit of a disingenuous statement there, really. What do you quantifiy as being 'many times'? I would hazard a guess that on average throughout the summer you would be lucky if it happened to more than 10 aircraft a day.

Thats a high estimate, so when considered against the amount of aircraft that carry out the full OCK2F Arrival it's a tiny percentage.

Swanwick AC controllers (who you would be speaking to at the time) would not have the time to issue an arrival instruction to every aircraft as some point further down the airway in an effort to get it 'right' first time, they are just far too busy.

Quite often as TC controllers we give late calls to AC, sometimes because we are a bit behind, but mostly because something happens which changes the dynamics in the TMA. Then we tend to cherry pick the aircraft - UK first as it tends to be easier to explain to them and/or aircraft at the specific request of Heathrow approach if they are in TEAM mode.


To be fair, although a good crew will have already started thinking about the arrival, all you have to do is punch the new one in... if you are being moved across, chances are you're going to have plenty time to re-brief the new arrival as you're gonna be holding for at least 20 mins!!

It's not ideal, but it works and it's what busy controllers have to do

Although Cartmans Twin knows what he is talking about, his statement ...it'sonly when the OCK hold becomes full that a 'stack swap' is considered.is a little misleading and might make a non ATCO think a late change is due to poor planning (though sometimes it can be)!

Stack Swaps are considered well before the stack at OCK gets full - done by counting back on the strips. Waiting until the stack was full is too late, and the sector would be going under!!

[Topofthestack]

Stack swaps from OCK to BNN are also done (mainly in the period between 0600-0645 and when LHR are landing on westerlies) to put aircraft who are parking on the northside of the central area closer to the runway for their gate. This is done to maximise the landing rate during that period. It means that the final director (the guy doing the final turns onto approach) is not faced with the issue of having to cross-over aircraft and ATC can stagger landing aircraft at 3nm intervals.