Question for ATC folk.

[Mouton Rothschild]

Picture the scene.

We are on finals in our 737 and there is another 737 about to depart from the same runway. The TWR controller has said "Expect late landing clearance, one to depart ahead" The one ahead now commences his take off run. During his take off run, we have an indication that requires us to carry out a missed approach. He is following a SID that requires straight ahead to say ALT 4000', and the standard missed approach procedure is also straight ahead to a similar level. His configuration means that he will have a higher ROC than us. Is there a standard procedure for resolving this type of conflict, or would the TWR controller still need to co-ordinate with APP/RAD ?

[opnot]

mouton
In this situation the published sid and missed approach are thrown out the window, both acft would be given turns away from each other.if necessary using the words avoiding action. co-ordination would then be carried when the situation had been resolved.

[Mouton Rothschild]

Thanks for the info opnot. Although I never saw this scenario for real, the Airport I was based at had a standard missed approach altitude of 4000' and the normal level for downwind was 4000' presumably due to the London TMA being above. If you turn one or both a/c, I would imagine you guys don't have a great deal of time to deal with the situation or co-ordinate! The system clearly works though. Thanks for doing a great job.

[HEATHROW DIRECTOR]

Most tower positions at busy airfields have radar too so the controllers can see what's going on around them. They will also be totally familiar with all the routes and restrictions around their airfield. They know what they can and cannot do and can certainly provide safe separation without immediate reference to the radar controllers, as opnot suggests.

Happy landings..

[opnot]

mouton
At Manch the standard missed approach of rwy 23 turns right onto a specific heading and climbs to 3500ft. Approach can, if they stay within the radar vectoring area descend to 3000ft whilst downwind for 23 ,however we do not descend below either 4500 or 5000ft until clear of the missed approach area, therebye ensuring separation between arrivals and go arounds

[Mouton Rothschild]

Thanks opnot,

I actually haven't flown for about 4 years now due to enforced retirement, but I dug out an old set of approach plates and sure enough my last post was total rubbish, the missed approach altitude was 3000 not 4000 as I had indicated. So we would not have conflicted with the downwind traffic. It was mainly how you dealt with the go-around with one ahead, which you have cleared up for me. What does hurt, however, is that you refer to Rwy 23 at Manch. This makes me feel really old cos it was still Rwy 24 last time I was there and 24L was still a building site!

[radar707]

Surely you wouldn't use the words "avoiding action" and would use the correct phraseology of "essential traffic information", or do you have SRG approval to use the ATM to establish separation in the tower????

[macker]

It's probably the main nightmare scenario for a tower controller, and where I work, it is dubiously referred to as a "piggy-back".

The conflict can become dangerous well below the missed approach altitude - even with similar types involved, the aircraft going around can catch up rapidly with the departure.

Prevention is far better than cure here but if it does happen this would be the drill:

1. if in VMC ascertain whether the aircraft going around can see the one in front - may not be possible with high angle-of-attack.

2. issue turns to both aircraft starting with the go-around aircraft. 20 degrees is about enough - may not be possible depending on local traffic or previous departure.

3. co-ordinate with radar asap.

The emphasis here is on avoiding a collision and then restoring standard separation as soon as possible.

It has to be regarded as an emergency situation, and hard-and-fast rules do not really apply. "Nothing in these rules shall preclude the controller, in his judgment..." and so on.

And yes it happened to me once. A real holes-in-the-cheese job. I resolved it but my life has probably been shortened by about 10 years as a result!

[GunkyTom]

To radar707

Surely you wouldn't use the words "avoiding action" and would use the correct phraseology of "essential traffic information", or do you have SRG approval to use the ATM to establish separation in the tower????

Yes, you would use 'avoiding action' if necessary. 'Essential Traffic' gives the preamble before any instruction or alternative clearance and is just time wasted if the situation needs resolving asap.I am surprised that an 'ATCO' from 'Warwickshire' would feel the need to ask that question as I too was an 'ATCO' in Warwickshire for many years and it is not something I or any ATCOs I worked with would feel the need to ask and YES we were authorised to use the ATM for that purpose but you could also use the Mk 1 eyeball!!!

[HEATHROW DIRECTOR]

I find all this talk of "avoiding action" and other stuff on here a bit scary! The aircraft should be under the positive control of ATC employing visual separation in the vicinity of the aerodrome.

[GunkyTom]

HD

What happens when the wx is such that you can't use vis sep ?

[HEATHROW DIRECTOR]

Use radar, as already described... I must have seen situations like this many times in my career but never felt the need to say "avoiding action".

[GunkyTom]

HD maybe I misunderstood when you talked about Vis Sep in vic.....etc It read as if that is how we operate all the time .I am in agreement re using the ATM. The point I was trying to make is Avoiding Action is an option, maybe you fortunately haven't had to use it but I have seen/heard it on more than one occasion in my many years as an ATCO

[chiglet]

I was on a "Fam Flt" in a Ba146. At "Decision Height" on rwy 24 at Manch..we didn't have a "Cabin Secure" signal which was an automatic Go Around. As the crew called this the Air Controller gave us a non-standard g/a [right turn heading 300degrees climb 3500feet] because we were IMC [cloud ceiling 200'] and there was a departure rolling...no real probs just the "one armed paperhanger" actions of the crew on this manual jet
watpiktch
Sorry about the punctuation but my comma key has gone AWOL

[vintage ATCO]

Use radar, as already described... I must have seen situations like this many times in my career but never felt the need to say "avoiding action".

Yep, 'avoiding action' is used. We had 'advances uses of ATM' and were permitted to use the ATM to resolve situations. Part of the TRUCE training in the sim.

[opnot]

HD
At Manch in dual rwy ops, our MATS pt2 says the words avoiding action will be used if g/a traffic is in conflict with departing tfc.

[Tarq57]

Miles away from the UK, here, but this sort of situation is guarded against in our neck of the woods. Where the weather is suitable for a visual circuit, the overshooting aircraft does that, and the tower controller provides visual separation in the usual way. Where circling minima doesn't prevail a departure will not be cleared to go once an arrival is inside a pre-set distance, which varies depending on the types and runway. This can be fairly conservative, as terrain nearby limits early variations from the standard miss. The distances have been determined by placing multiple scenarios on the sim, then rounding up the distance required, to pretty much guarantee that the radar separation will be maintained throughout.
The downside is that when the weather is bad the delays can start to mount up, as gaps have to be created between arrivals to allow for departing flights.
It's a bit of a blunt tool, designed to guard against a situation that doesn't actually happen that often, but the view (correct, IMO) is that if the weather is below circling, an aircraft can make a missed approach at pretty much any time, for any number of reasons, some of which mentioned above, and when that happens, even if it's just once a month, it should not be necessary to treat it as an emergency situation.
It's a right pita when the weather is bad and traffic heavy, but it's default-safe.

[2.5 miles]

"Avoiding action" almost certainly been added to the scenario due the urgent need for a turn from the G/A traffic. Problem being that, as I understand it, the G/A traffic needs to be stable and in the climb plus other checks made, before it can make a turn. I think the instruction was incorporated following a particularly late G/A of a foreign 747 "piggy backing" a departure at Manch? A turn may be "non standard" in relation to the published missed approach, but surely any procedure comes with the caveat "unless otherwise instructed by ATC". The point being that it is the ATCO's responsibility to establish standard separation between the 2 a/c as soon as practicable (reduced sep in vicinity aside).

[HB-UAE]

separation

Kind of depends on what sort of RWY separation the ATCO is using. Basically said if there is enough space between the both of you there is no need for major coordination, however since a g/a is an *unusual* situation there will be coordination done anyway.

The way I look at it is... the landing a/c will usually climb better then the departing a/c lighter, TOGA power etc. the stress level for the go around crew is usually much higher as well so I tend to try to keep it simple, safe and sound for the g/a. The departing crew can usually without problems stop climb.

e.g. SID to Alt 4000... go around initiated whilst dep is passing 1000ft then just tell the dep to stop climb at 2000. by the time the go around actually is realised or can be dealt with it is usually already climbing though 2000ft or higher because boy do they like to climb ;-)

Hope that makes sort of sence, probably doesn't but anyway bottom line is: always depends on the situation and aircraft type involved. Mostly reclear the departure and let the go around climb or simply if they are too close, turn them in oposite directions!!!!!

cheers

HB-UAE

[anotherthing]

I find all this talk of "avoiding action" and other stuff on here a bit scary...

I assume that I am in the minority when I think that the phrase "avoiding action" is under-used?

Avoiding action is a tool that should be used... even recently I have watched controllers sweating buckets waiting for separation, but they still never utter the 'avoiding action' words.

They just turn the aircraft without giving the pilots any indication of the neccesity for a hard turn.

I can only think that it harks back to the days when you had to fill in a report every time the words were uttered (in civvy street) - a completely ridiculous and obstructive course of action.

Fortunately it is no longer how things are done, but controllers who have no military experience are still very reluctant to use it.