Are you thinking of WCO before BNN? There was nothing like a "WCO snatch" when Heathrow were on Easterlies.

A WCO snatch at the end of a tour was always a special treat.

Thanks Heathrow Tower. Very interesting. The scheme seems to use a series of a variables in a systematic way, which suggests that it lends itself to automation. I assume that controllers would have the final say and ability to override any automated system but do the tools that you use suggest an optimised sequence based on these variables?

I'm not sure automation is the right solution. Where there's humans involved, automation can go to pot very quickly!

Excellent post Heathrow Tower.

I think you elude to it with CTOT and calculated push back times, but is there some element of the system trying to create push back times in order to deliver the aircraft at the hold points for the runway in roughly an optimal order, or is this purely a human endeavour?

I could envisage automation helping to resolve the multiple variables in the equation, and offering a 'best solution' to ATC. I'm not sure that the input end of that process would work terribly well, though ... again, to many variables (lack of tug, late pax etc.). And once the aircraft is actually moving the options for revising the departure sequence diminish.

There is an alogrithm.

It takes the TOBT (target off blocks time) reported by the airline which may / may not be the same as the schedule. This is the time the flight is expected to be ready to depart.
The alogrithm then adds in a load of variables (aircraft type, flight plan, stand, runway in use, estimated taxi time etc) and looks at everything else wanting to leave around that time and builds a departure sequence.
This determines the TTOT (target take off time) and displays the TSAT (target start approval time) to the flight deck on the screens in front of the aircraft
If there is regulation either locally or in wider EU airspace then a CTOT may be issued which is fed into the algorithm to determine the optimal time to release the aircraft from the stand - if there's a shortage of stand space you can be moved to a remote holding point.

Assuming the flight deck call ready at TOBT (there is a +/- 5 minute leeway) then the aircraft will either get immediate push back approval or be held on stand until TSAT. If the CTOT is generating a much later TSAT then the ready call gets fed into the wider system at Eurocontrol to push for an improvement and reduce the delay.

Some airlines try to game the system by moving TOBT by 5 minutes every 5 minutes when they have a delay but that is actually self-defeating as it creates instability in the departure sequence and can lead to delays for other flights as the algorithm tries to fit them in.

Have a look at ACDM on the Eurocontrol website; it's interesting stuff (and something I worked on with Heathrow and, to a much lesser extent, at Gatwick many years ago).

EDIT: I hasten to add that I didn't work on the algorithm itself, but more the underlying processes the airlines and ground handlers need to follow with analytics to monitor and measure performance (I just realised my sentence above made my role sound way grander than it really was!)

So that's why we get photos of A380s looming over the A320 they are following? :)

More seriously, do you (ATC) have any influence over the choice of departure route, in particular when it doesn't increase the distance much? Can you, for example, influence the use of a northerly departure in the evenings for some flights? Or is this entirely the choice of the airline and Captain?

Apologies for not replying sooner, thank you all for the comments. I'll reply to any questions in this thread throughout the day!

Not in this case - was thinking particularly of the predecessor beacon to BNN for North-westerly arrivals.

Frequenting MAN-LHR, I too offer up a silent prayer for a snatch shortly after we level off (i.e. a few minutes before we get handed off to the LTMA controller) if I know Heathrow is on Easterlies.

Are you thinking of Honiley or Daventry? They are the next two heading north west.

https://t.co/N2UsyikkQu

No, this is a long-gone beacon... gone some time in the 1970s. :D

I just remember seeing it on a rather old approach plate. I think it was actually co-located on Leavesden Aerodrome, and got replaced by BNN when Leavesden shut down, I suspect around the same time as Ongar was replaced by LAM.

What sort of thing? Anything in particular you'd like to know more about?

I mean apparently we have plenty of long breaks...... :D

In terms of wake turbluence, 747s of all flavours are Heavies. However, and this can catch an unsuspecting ATCO out, on the ground we also classify aircraft based on their wingspan, and undercarriage dimensions etc, into 'Codes', when we talk about taxiway and stand restrictions.

Code C is A319/20/21, 737 etc
Code D is 757, 767, A300
Code E is A330, 787, 777, 747-400
Code F is A380, AN124 and B747-8

(and also the 777-8 and 777-9 will be Code F on and very near the runway, but Code E at other times).

They are going wheel-to-wheel towards RWY 09L now. Who is going to be last on the brakes?

BAW283 goes off-track, off goes BAW213.

THROUGH GOES BAW93, UNBELIEVABLE STUFF COMING OUT OF THE FINAL CORNER.


​​​​​​​+bonus points if you read it in Crofty's voice