CTOT -5 at LGW
 

Over the past few months I've noticed that LGW hardly ever allow us to go at CTOT -5.

Is there a policy of always aiming for the exact slot time even if an opportunity exists to allow a departure at -5?

The only time I've got away at -5 recently was when nobody else was at the hold.

Thanks

SW

Sky Wave,

No policy for not letting you go at CTOT -5, we are just aiming to maximise the utilisation of the runway, if CTOT -5 helps that then you'll go then, if it is CTOT +10 that suits then we'll depart you then.

I suspect that it is a factor of us getting busier that you are departing into your slot more regularly.

SH

CTOT -5 at LGW
 

Over the last week I have had a slot caused by en- route issues and the controllers at LGW have done an excellent job of getting me away at exactly CTOT-5. I think it's down to how busy the airfield is.

If you're number 1 to depart at CTOT -5 (and note that doesn't necessarily equate to arriving at the holding points first) then you'll go at CTOT -5. But there are a shedload of factors which decide where you are in the sequence including start times, route, delay already taken (on stand or remote), relation to other traffic types/speeds/climb performance, type and performance of the landing aircraft between which you're going, etc.etc. If you're LGW based, come and visit us....speaking personally, there are some airlines I'll very rarely try to depart in a tight gap because I know they'll be slower to roll than others even when told to be ready for immediate:ugh:

Thanks for the replies everyone.

I realise it's impossible to know the plan but it seems that regardless of how early we get to the hold point we'll still wait for our CTOT if any other unrestricted aircraft is ready. The average seems to be arrive at M1 or J7 around CTOT -10 and then wait until CTOT for line up clearance even if you've been remote holding for the past 30 minutes.

It's not a problem and I'm not criticising, I just wondered if it was a new policy or if it's considered "professional excellence" to get aircraft away exactly on CTOT. ;)


I've been up a couple times before, it's a bit more difficult these days because the company won't pay for the bus when we're on airport standby. It will probably have to be a case of visiting after work one day but no idea how I'd get out to you.

Hope it's not us with the orange bandanas! If it is then all I can say is we have more than our fair share of training flights and lower experienced FO's.

Cheers SW

Sky Wave,

I think you have just been unlucky with the traffic situation, I have just had a quick look at todays stats. 19 of your company aircraft have departed with CTOTs today, 13 departed in the 5 minutes before the CTOT and 6 in the 10 after.
Just a random sample from a single day, but I think it helps to show we have no policy of holding you back for the exact CTOT.

SH

With regard to remote holding we are sometimes guilty of starting you up a little too late to get airborne in the first few minutes of your slot window. This does get noticed and conversations had so we are trying to improve!

On the other hand it is not uncommon for us to approve your start and be told that "we would like to wait another 5 minutes".

With it being very busy now both these scenarios occur with little time on both sides to get into a discussion about earliest airborne times and how busy it is at the hold etc.

Personally I take it as a personal failing if I don't get you to the hold in order to be airborne as close to -5 as possible.

If you started with no delay I'm afraid it's luck of the draw. Anytime between -5 and +10 is acceptable if using the runway to its max and departing as close to start up request order as possible.

CTOT -5 at LGW
 

Officially its airborne exactly at CTOT. The -5/+10 is to accomodate taxi delays. Fly to Sweden and some Spanish airports and you'll know...

The -5/+10 window is for atc sequencing if needed.

I work as a tower controller in Sweden and have no problem letting you depart at CTOT -5 if there's no other factors to consider...

Then you are doing it wrong and ruining it for the rest of us!
If there are no other factors to concider (a departure sequence) then the aircraft shall depart on CTOT.
This is exactly why pilots get confused!

So hang on, the OP wants to get away at -5 but you want to get away at CTOT?

Last time I checked the AIP says "A slot window of -5 to +10 minutes is available to ATC to optimise the departure sequence."

Where I work the above means we would most likely start the aircraft in good time to make CTOT....prob 5 mins early....and then we sort it out depending on when aircraft requests taxi, other traffic, etc., etc.

So sometimes you get to go a few minutes early, sometimes (rarely) exactly at CTOT, sometimes a few minutes after.

It's not rocket science.

When I worked in the UK (a long time ago now) I used to try and hit the CTOTs on the money but there are times when you have two or three departures with the same CTOT going to different places and some unrestricted traffic and you used the window accordingly.

I thought then, and still do now, that a 15 minute window (with the +15 some airports were allowed to utilize) on a flight as short as an hour or so, was hardly a guaranteed method of smoothing the flow down the line.

Where I am now most flow control is dynamic. Times are requested on taxy and tolerances are much finer. +/-3 minutes for most destinations and ORD is just -3. A 3 minute slot window should provide a better flow but it does mean that on a mixed mode runway you have at best two gaps to hit it and sometimes just one.

When Ground Delay Programs (GDPs) are in effect we are expected to hit the time as close as possible, all things considered.

If there is no departure sequence, meaning the aircraft concerned is the only departure you have, then our duty as ATC is to get you airborne bang on your CTOT. (Arrivals permitting) Its that simple.
All ATC units with departures subject flow control from NMOC (previously Eurocontrol CFMU) must follow these rules.
So yes, sometimes it feels pretty pointless to wait at the holding point for 5 minutes when theres noone else around you but the system is there to protect both ATC and operating agencies.

CTOT -5 at LGW
 

My solution is just to ask "what's our earliest airborne".

Seems a bit crazy to have aeros sitting on the ground at the holding point just because they've arrived there 5 mins ahead of their CTOT, especially when EASA, NATS and Eurocontrol are all shouting "reduce fuel-burn, reduce costs, reduce CO2", etc. I wonder how much changing the name of the CFMU to NMOC has cost?

According to? Reference please.