Traffic Info - above or below

[tori chelli]

It has occured to me, pottering from unit to unit at not quite 3 figures, that I receive TI from different radar people in different ways.

Some give "Unknown traffic...indicating (say) FL35, unverified" and some give "Unknown traffic...(slightly) above/below".

I notice your MATS Pt 1 refers to the latter, but the former seems just as relevant to me. Is there any preference as to which is used by which unit?

Slightly confused,
Tori

[average-atco]

For me giving a service outside controlled airspace I would specify the indicated level and confirm that it isn't verified , also climbing or descending if that is relevent. I think the point is to paint the best picture you can with the radar derived information you have.

[Dr. Evil]

also climbing or descending if that is relevent

as well as:

moving left to right or right to left
slow/fast moving
o'clock postion
distance

[Evil J]

I tend to use either depending on the context. If two are merging and I think it will be more beneficial for the pilot to know relative height ie "two hundred feet above" or "slightly above" I will use that. If its a bit more generic I'll use the levels "Traffic one o'clock 6 miles indicating 3 thousand feet" so I wouldn't say there are any hard and fast rules.

[almost professional]

evil j
you are more sad than me-shouldnt there be something better to do when we get home from work!

[AirNoServicesAustralia]

I know when an aircraft has a clearance and you give them traffic information as a heads up as to why they have been levelled off below their requested final level, and also to help them with when they can expect to get further climb, I never say "traffic crossing from your right to left 5 NM FL280". I would always say "traffic crossing from your right to left 5NM 1,000 ft above". The reason is two fold for this, one is to avoid the transmission being possibly clipped or over transmitted and the pilot hearing their callsign and a FL, and going ahead and climbing to that level. Also in many parts of the world the level of English comprehension is basic to say the least so these pilots are known to hear and understand only the basics and again, may jump to the wrong conclusion and start to climb to said FL.

I know the giving of low level traffic information is a little different, but I was always taught the blanket rule, that you should never say a FL or Altitude unless you are happy for the pilot to climb to that level/altitude. Same goes with when a pilot says "request FL360", my response would never be "FL360 not available", I would always say "requested level not available", and tell them what is available, or just sayer "higher levels not available" and give a reason if time permits.

[tori chelli]

Thank you for the replies. I realise that additional information such as "crossing" etc is also added.

My main query was the insistance, or otherwise, of Unit bosses insisting that TI on unknowns was only given as per MATS Pt1. I prefer being given a 'target' level to look out for rather than a generic 'above' or 'below', so I'm pleased to hear the latter is not mandatory.

Any other units got an opinion?

Tori

[PPRuNe Radar]

I think the MATS Part 1 makes sense.

If the aircraft is displaying a squawk which is not deemed validated (e.g a conspicuity code), then we can't assume the Mode C is correct. If it's not correct, then by stating that the aircraft is above/below may lead the pilot to concentrate lookout in the wrong place, thus the method I prefer is 'Unknown traffic, (position), indicating FL/Alt, unverified.'

It's then up to the pilot to assess where to look, initially at the indicated level, but they might also get their scan going up as well as down if they don't find it there.

For traffic where the Mode C is verified, then using the vertical distance above/below is the way it should be done to avoid the problems ANSA alludes to.

As an aside, ANSA, do you get a lot of unknown traffic in the Upper Airspace in your part of the world ?? Would imagine there might be a few mil things whizzing about as laws unto themselves.

[DFC]

I personally prefer ATC to specify that a flight is xxx ft above/below and add "unverified" if that is what it is.

The reason being that it saves me having to compare my height and work out the difference..........much simpler to think 3000ft above...not a problem, 300ft above....eyes on stalks.

Yes one can'e be sure of unverified transponder mode C. However, airworthiness requirements keep an eye on the accuracy of mode C and hand on heart, I can only think of 1 case of a mode C being out of limits in the last 25 years.....and that one was 30,000ft out!

As to the problem of a mode C error causing the aircraft to be above when it is indicated as being below, considder the following;

You point traffic out as same level 12 O'Clock.........I will not always see that aircraft in my 12 O'Clock. It can be in either my 10 O'Clock or my 2 O'Clock depending on my TAS and the Wind. The reason being that you see my track and I see my heading when I look out and with a strong wind and slow aircraft there can be 30 deg difference..........but do ATC warn us that the clock may be slow? ;)

Regards,

DFC