Formations & Squawks.

[Toadpool]

An incident the other day has started me thinking about this issue.
I was vectoring traffic inbound, in class G airspace when I observed conflicting traffic. 2 contacts on parallel tracks, 1 squawking high level, the other not squawking.

Due to time constraints I elected to avoid the non-squawking traffic rather than co-ordinate. When I checked with the other unit working the high level traffic it was confirmed that the second was in formation with the other and were "just joining up".

In the present environment, when ACAS/TCAS is becoming more important, certainly in the civvy ATC world, would not be preferable to have all elements of a formation on individual squawks, unless they were garbling?

I feel that making the assumption that as the traffic is travelling in the same direction and speed it must be in formation a bit dodgy, particularly when the elements of a formation can be 3 miles or more apart, and often at a significantly different level.

[radar707]

By the very nature of formation flying they are close together therefore you will get garbling of squawks, so having individual aircraft in the formation on individual squawks would not really help.

Sadly it's just one of th eperils of providing a radar service outside CAS, you have to do the best job you can to provide a RIS / RAS, otherwise just go for a FIS and let the pilots have the problems of flying outside CAS.

At the end of the day in this litigous society that we live in, I'll be surprised if employers will start to allow non LARS ATC units to provide anything other than a FIS

[Spitoon]

I'm going to assume you are talking about UK airspace - don't know the rules that might apply elsewhere.

Following an incident a few years ago the rules on formation flights were reviewed and clarified. The revised procedures are in MATS Part 1 (Section 1, chapter 4, paragraph 16) and they say that within CAS only the lead aircraft squawks. IIRC the incident that led to the review involved a very loose formation and an AIRPROX with one of the extreme aircraft (nearly 1000ft below the lead I think). The procedures were tightened up to specify the maximum spread of the formation and what to do if it needs to break for any reason.

Of course, the incident happened on an en-route sector which doesn't have PSR (one of the reasons that the controller had no idea hat was about to hit him/her) and the review involved people from that environment. Perhaps there might have been a different outcome if someone who works PSR outside CAS had been involved....

And dodgy isn't the word - I wouldn't make any assumptions about more than one target doing much the same thing!!! But at least the en-route people don't need to worry about such things!

[orgASMic]

We (Mil) would run out of squawks pretty quickly if all elements were given individual ones. They start to garble surprisingly quickly even if the aircraft are a mile or 2 apart, which is no use to anyone as the display will often default to 0000 and lose the Mode C.
Stream formations will be given extra squawks, typically to the lead of each section or to the middle and tail elements to aid identification.
If aircraft are joining up, all elements will have individual squawks and be separated vertically until visual with the leader and cleared to join, at which point they will squawk standby to avoid garbling.
In CAS we will confirm that all elements are same level within 1nm (what used to be called 'holding hands'), though my idea of 1nm can be quite different to a pilot's.

[danieloakworth]

As stated lead only squawks in formation. However, should a formation become stretched I tend to offer ATC the option of the rear and front squawking, as I guess it helps (particularly if the stretch is vertical rather than horizontal).

[anotherthing]

Daniel

I would be very worried if a formation became 'stretched' vertically. If they do by more than a handful of feet then they must be considered separate units.... otherwise the poor ATCO providing 1000' separation against a formation he believes to be occupying the same level is going to get a bit of a shock when he has an airprox.

Our tolerance for mode C is plus or minus 200'... I suggest that formation flying in the vertical plane (sic) that deviates from anywhere near this figure (and lets be clear, it could only happen like this if you were VMC or very intermittantly IMC at the very worst) must be considered to be separate units. They are not holding hands.

orgASMic has already posted the rules regarding formation flying and squawk allocation.

[CleartoFire]

I do lots of formation joins and I tend to keep all elements squawking individual discrete squawks (allocated to our unit) until they are "holding hands". Once the aircrew have confirmed they are in formation then I will instruct all aircraft except the lead to squawk standby.