Who goes first?
 

I was a pax departing Singapore and there were two lines of taxying heavies converging on an intersection, to reach the departing runway. It raised the question in my mind: How does the ATC decide who gets priority in a converging queue? Would it be booked slot time, size/climbing speed of aircraft, departure SID, first come first served? Or a combination? I assume there is a procedure, not just at the whim of the controller? Quite a complicated decision if all factors are taken into account, and has to be reviewed for each pair as they reach the merge.

And I guess every pilot feels he/she should go first?

Thanks!

Easy, in that situation in Singapore, Singpore Airlines always goes first, on the ground or airborne, it doesn't matter! :}

Regards,
BH.

It`s easy, the airline that gives the best discounts and most frequent upgrades for Atco`s goes first! Well there has to be some clearly understood method lol!

<<not just at the whim of the controller>>

Well, yes, it is the controller who makes the ultimate decision about the departure order. However, he takes into account many factors, some of which you already mentioned. He has to determine separation, based on the route after take-off (SID - left or right turn-out), type of aircraft (speed consideration) and whether wake turbulence separation is required. Slot times play a part too, which is why aircraft are sometimes taken out of the queue to depart ahead of those in front.

It is a complex job but, much like the work of a pilot, it becomes second nature to properly trained controllers.

The aim is to achieve the best overall departure rate (maximum number of aircraft airborne in the minimum time) without in any way compromising safety, and taking into account the factors mentioned by HD.
A similar principle applies to inbounds to achieve the best overall landing rate.

james ozzie,
You're right about pilots wanting to be first.We have a certain airline that arrives and departs all together.Their pilots have been known to phone ATC complaining that they were number whatever, behind their own company aircraft.:rolleyes:

It certainly can be and when all factors are equal we invoke the "tie-break" factor. Which airline upgrades controllers?

On the beach :ok:

Speaking from personal experience in Singapore it seems to be first-come-first-serve. I haven't experienced much "tactical shuffling" of departures in the region.

S.

How is the departure sequence changed when ac are taxiing in a line?

Cottam... I thought you were an ATCO?? At major airfields there are usually a number of routes to the holding points and plenty of room to have several aircraft hold to one side so that others may pass. Have a look at some charts of major airfields and I think you'll see what I mean..

I was a Mil ATCO, doing area at the College at the mo. Not something we do in the Mil

Ah OK. Good luck wherever you end up..

<<there are usually a number of routes to the holding points and plenty of room to have several aircraft hold to one side so that others may pass.>>

HD, in view of last weeks report on this very subject at our very own favourite ex- workplace, that's a very brave statement;)

Yes, M, I remembered that right after pushing <return>!!!!

Not at all ! As this picture would show you !
Photos: Airbus A330-342 Aircraft Pictures | Airliners.net

AFAIK, arrival a/c have priority over departure a/c at most intersections. And it also involves the slot times(off chocks) as well.

<<AFAIK, arrival a/c have priority over departure a/c at most intersections>>

Only when the arrival is leaving a runway. Otherwise, there is no such priority.

"Who goes first?" Now there's a question. My experience to date:

In the UK, Netherlands, Denmark, Norway, Italy, Finland, Sweden, most of Germany, most of France a first come, first served approach (or departure) is followed subject to a bit of shuffling for slots, improved departures sequences or plain common sense.

But, I have fond memories of waiting for Brussels Airlines at BRU (many times), Luxair at LUX (lost count), German Wings at CGN (one morning in particular), being squeezed out at NIC for an AF, moved aside for an Iberian descent in BCN, made to give way to a Nikki or two at VIE (yesterday) and so on. Some of these were so blatant as to beggar belief and some were very subtle, but local favouritism still rules OK in many places.

PM

Sure, and locals will always tell you that foreigners are always favored.

When speaking of local favoritism:
The local pilots tend to know a little bit more about the local geography and are more willing to do tighter approaches. If two similar A/C (one foreign, one local) is going to be overhead the inbound fix at the same time, and I see an opportunity to tighten in the local, I'll do it.
But that's on approach.

On departures I try to be fair, but safe and expeditious flow of air traffic is my main priority ;-)
We have some slow movers at my field, and they have to be let go sometime.

Normally it's GND that makes the departure sequence. TWR may change it if necessary.