Radar information - what's the altitude?

[Riverboat]

When being given an RIS, I don't like the current practice of advising aircraft that they have conflicting traffic at (for instance) 10 o'clock "2500ft below" or "1500 ft above". 2500 ft below isn't very helpful to me when I am descending, because I have to do some arithmetic and by the time my slow brain has worked it out I am probably 1000 ft closer to the traffic than I was! I'd rather be told that it is at a particular altitude - "3000 ft", so that I can quickly and easily picture where the traffic is, and assess the significance.

Why did the practice change?

[Defruiter]

As far as I know, there were some instances where people were mistaking that as an instruction to climb/descend to that altitude, so they changed it soay it was a certain number of feet above/below. Im sure someone can confirm/correct me...

DF

[neilmac]

As an PPL IMC Holder for 12 years and a current ATC for 6 years, we tell you what it is on our screens! Under RIS i should remind you are responsible for your own separation! And why would I know what pressure setting say a 7000 squawk was under? can only go on what the screen tells us!! Do you want me to fly the plane for you?

NM

[airac]

Why did the practice change?

It hasn't . If in doubt ask the ATCO to give you the contacts level , be it verified or unverified


And why would I know what pressure setting say a 7000 squawk was under?

neilmac

Isn't the altitude displayed dependent on the pressure set in the equipment, therefore what the A/c has set is irrelevant?

Any way under the proposed changes all you might get in future will be
" :eek:, that looked close "

[neilmac]

Your right radar set on 1013mbs, I have PM 'd Riverboat to explain!

[BurglarsDog]

As NM says the current hourly regional QNH should be typed into the radar database. All acft flying away from the circuit below the TA would be on this If memory serves me corectly, the controller will then see an altitude relevant to that setting. Cant remember exactly how the computer assimilated the altitude of acft above this. I think that what you saw was always displayed relative to the QNH value entered just that above 3000, the altitude had a 0 put in front of it to show a FL?:confused:

Anyone??

As to whether its verified or not the give away used to be in the ATC phraseology. If the conflicting traffic was wearing a known SSR code then its vertical position would be described to you using the term :
" ....AT 3000 etc"

If however the SSR was unknown i.e 7000 then the term :
"... INDICATING 3000 etc" was used.

Was 10 years ago though so things in the UK (MIL) may have changed.

DogGone:ok:

[Chilli Monster]

Your right radar set on 1013mbs, I have PM 'd Riverboat to explain!

Not a lot of use when the QNH is significantly different - don't you input that into the console? (means the levels displayed below transition altitude at least have some bearing on reality).

All acft flying away from the circuit below the TA would be on this If memory serves me corectly, the controller will then see an altitude relevant to that setting. Cant remember exactly how the computer assimilated the altitude of acft above this. I think that what you saw was always displayed relative to the QNH value entered just that above 3000, the altitude had a 0 put in front of it to show a FL?

Correct (apart from levels 100 and above which are shown as a whole number with no preceeding '0'). Database knows Transition Altitude for your airfield (in our case 4000 ft) and adjusts displayed data accordingly.

[HEATHROW DIRECTOR]

<<I have to do some arithmetic >>

Hold on... let me get the Kleenex hankies out!

[Dont tell um pike]

This covers it i think , more rasy than risy but you get the idea

"Under some circumstances, controllers may consider it prudent to inform a pilot of other traffic which is separated from his aircraft. In such cases, to prevent any possible confusion, no reference should be made to the actual level of the other aircraft. If necessary, the pilot should be informed that the other aircraft is '(number) thousand feet above/below'".

DTUP

[Giles Wembley-Hogg]

On a point of pedantry. I believe the term "Regional QNH" is incorrect. As I understand it there is a "regional pressure setting" and a QNH.

The Regional Pressure Setting is a forecast of the lowest QNH value within an
altimeter setting region. The values which are made available hourly for the period H + 1 to H + 2, are given in whole millibars. MATS Pt1 Sec 1 Ch 6 Page 1.

I'd be interested to know if it is the QNH or the RPS that is being fed in to the Mil radar sets.

BurglersDog is not quite correct when he says that all aircrsft away from the circuit would be on RPS. No datum is specified (except when flying beneath a control are). I fly around on the local QNH whenever I can. Getting this from a military radar unit can be like pulling teeth though!

The "traffic 1000' above you" type of phraseology works well in controlled airspace where people tend to fly around at specified levels and there is scope for confusion. Outside controlled airspace I don't believe such confusion would be generated by actually reporting the level of the conflicting traffic eg. " traffic indicating 3200' unverified" etc.

I am all for standardisation, but I believe it can be taken too far so that the unexpected consequences outweigh the expected benefits. Giving the runway entry position at the same time as a line up instruction is another case in point. I now have to read back so much before I can get on to a runway that I hold all the information in my (very) short term memory. If you asked me 30s later what I had just read back I would struggle to remember. So whilst someone in an office thought they were making things safer by making me say "After the departing Midland A320 line up and wait runway 27L via N1" (even though the holding point between me and the runway is NB1), the key fact that I should line up after a Midland aeroplane is potentially lost as I try to resolve a bit of confusion as to where I should line up. There should be no confusion as there is only one way to get from where I am on to the runway, but still I am made slightly uncertain.

I rambled there a bit. The point I was trying to make is that we are starting to overcomplicate things. If you hear "Wembley-Hogg 001" on frequency, please just tell me what level the other traffic is at if I'm outside controlled airspace.

G W-H

[BurglarsDog]

GWH Correct :D
I was only generalising. RPS it is: Barnsley Holyhead etc
And of course being the lowest forecast for the period anyone flying on that instead of a local QNH will always be higher/ safer where terrain is concerned - but of course nearer to anyone overflying them, on the local QNH (or in the case of the mil within a MATZ- QFE), at what appears initially to be a safe alt above.
I cant remember what the mil or civs put into their radars,(1013 maybe as a standard ref) Im sure someone will soon tell. But I do know that when trying to coordinate arrivals and deps with LARS traffic, quick, accurate mental arithmatic was part and parcel of the daily tasks in order to work out whether you had the 500 or 1000' needed. Indeed as an RAF Instructor I often found that the pressure questions in an ATC groundschool phase were always a good test of the speed of a students processor so to speak. Often those that struggled to add or subtract correctly under a modicum of time pressure werent so good in the sim.
DogGone:ok:

[NorthSouth]

neilmac: we tell you what it is on our screensBut that's just what you don't do - as riverboat said, what you actually do is read the Mode C of the other traffic, check against the Mode C of your own traffic, subtract one from the other, and give the result to the pilot of your traffic. Must be quite a lot of extra workload when busy, and lots of scope for error and confusion, not that I'd suggest ATCOs ever make errors:)
NS

[Radarspod]

Transponder outputs altitude report in 100ft (or 25ft if Mode S and capable) based upon 1013.25 mB pressure. Setting QNH on altimeter, etc, will have no effect on the transponder. This will lead to transponder reported height being different to altimeter report based on QNH. Some of the more advanced radar processing and display systems will QNH convert the transponder altitude report when below transition altitude to give aircraft altitude in feet based on QNH rather than a Flight Level on 1013.25mB
What will be consistant is the difference in height between targets using the same 1013.23 mB pressure reference. So it is probably more correct to state differences in height of local traffic rather than their actual height AMSL that the radar display shows.
oh, and before someone makes a smartarse comment about transponder altitude reports being called Mode C, Mode S equipped aircraft (88%+ of all transponder equipped aircraft) do not use Mode C when responding in Mode S - hence I didn't call it Mode C.:ok:
I'll get off my Mode S soapbox now.........:}

[Spitoon]

As Radarspod points out, most radar display systems can be configured to convert the level reported by the transponder to another datum (instead of 1013.25 hPa). The setting chosen is going to be that which best suits the ATC operations. I'm an aerodrome person and all the radars I've ever worked have used the aerodrome QNH but if a unit provides a service that is not orientated around a particular aerodrome, a LARS for example (OK, a very UK example), it would probably make more sense to use the RPS because it is likely that many pilots will be using this setting.

Again, Radarspod pointed out that what we can be reasonably sure of is that the relative difference in reported altitudes is correct. As a controller providing services outside controlled airspace, I am going to be very aware of the differences in actual levels that may exist because of the different pressure settings used, quite legitimately, by different pilots. Where I give traffic information on another aircraft that I know is on a markedly different pressure setting I will probably give the level in relative terms - because, quite frankly, I can't be bothered to do the math. If I know the aircraft are using the same - or very close - data for altimeter setting I will probably give the level reported by the transponder. Bear in mind that the level information is likely to be unverrified anyway!

I would make one final observation. The pilot is flying according to the VFR - the information that the controller provides is intended to assist the pilot, not to replace looking out of the window, and is subject to workload and other factors. If a pilot wants more assurance of collision avoidance from the air traffic service there are more appropriate services to request.

[airac]

At the end of the day if I am providing a service to A/C they will be on my pressure setting, unless they are flying on 1013.2 .Therefore why have I got to worry about what pressure setting they are on .
Thats why I give the a/c my QNH.
If I am not working them, depending on the service I'm providing the maximum I have to do is , either seek to achieve 5nm or 3000' if I'm going for vertical.
If the squawk and charlie readout is validated and verified by an adjacent unit and co-ordination is acheived the slight difference between QNHs will hardly be noticed since the mode C readouts are to the nearest hundred.
Besides QNH is adjusted locally and A/c have A next to the level and Flight level has F next to it .
Where is the problem guys?

[ShyTorque]

In my experience, ATC may say something along the lines of: "Traffic 11 o'clock, 3 miles, indicating 2400 feet unverified".

I take this to mean they are not in comms with the other aircraft and are merely reading off his Mode C indication. All encoding altimeters use 1013 as the datum so if necessary I might dial in 1013 mb on my second altimeter to check how his altitude compares to my own. Not difficult and is normally enough to help spot and ensure separation from him.

It is important to realise that his transponder may be giving a false readout; it would not have been confirmed in real time by the other pilot, due to the lack of ATC comms with him.

I also have the benefit of a TCAS; my readout should match the ATC report. However, as it also relies on his (the other pilot's) transponder being correct, it isn't completely infallible (in reality a transponder is only seldom very far out, it is checked at least annually, as part of the C of A airtest).

[AlanM]

Traffic 11 o'clock, 3 miles, indicating 2400 feet unverified

Good to hear that someone likes my traffic info!
It is ambiguous, and short and choppy. I also emphasise the INDICATING and UNVERIFIED bit.

[Gonzo]

I usually add "OH MY GOD HE'S HEADING STRAIGHT FOR YOU!!!!" and that tends to get someone's attention. :ok:

GWH, I agree with the new line-up phraseology. Hate it. One has to say it all very slowly to many operators to ensure they understand you, and it seems to go on forever! :ugh:

[Talkdownman]

""In my experience, ATC may say something along the lines of: "Traffic 11 o'clock, 3 miles, indicating 2400 feet unverified".I take this to mean they are not in comms with the other aircraft and are merely reading off his Mode C indication. All encoding altimeters use 1013 as the datum so if necessary I might dial in 1013 mb on my second altimeter to check how his altitude compares to my own. Not difficult and is normally enough to help spot and ensure separation from him.""
It is pointless to dial in 1013. Below the Transition Altitude the Mode C is automatically converted from that encoded on 1013 to altitude, verified or not. Remain on the controller's QNH. That is the setting fed into the radar.

[ShyTorque]

Talkdownman,

Ah, point taken, but I might not be on the local QNH at all; I might be on RPS if it's a military radar unit. Local QNH at military airfields seems to be a military secret ;)

I did say my second altimeter (co-pilot's side and I don't have a co-pilot). I obviously don't fly on 1013 if not at a flight level. I do sometimes need to have 1013 set on the other altimeter anyway, for example if climbing IFR to cruise in Class G under airspace which has a lower limit defined as a flight level.

[Say Again, Over!]

:)

Riverboat,

I use this practice where I work simply to avoid an uncommanded climb. You shouldn't have to do math from it though. If we report traffic that's 1,000 feet above you, then that's all you really have to know. You don't even have to know your own altitude even; you know the traffic is a thousand feet above you.

I use it too when someone is climbing to 7,000 and another is level at 8,000. I'll say to the one that's level: "Traffic will stop a thousand feet below", especially, in an approach environment, if the pilot might be expecting descent soon.

It would be unwise to use it when the traffic is inconflict and at an incertain altitude or if it is unclear whether it is climbing, or level. So if I see traffic ahead of you at 2,700 and you're level at 2,500, I'll say the altitude since that traffic might be on the way up or down or level and either way still a conflict since he's within IFR and VFR sep minima.

I always found that "He's at the same altitude as you headed straight for you" works better than giving the altitude, position and direction and letting you figure it out a second later. :}

This being said, you won't hear me give out traffic info unless you cross the pond... :}

Cheers,

SAO

[Widger]

To get back to the main thread. It was indeed changed because there had been incidents where aircraft under RAS had climbed or descended to the level reported. There is nothin wrong with providing a direct readout but, sometimes it is easier to say indicating 500' below. If you are military you are also taught that indicating means unverified and at means it is verfied so no need to add those phrases on the end of the transmission.

Also, setting the QNH is all well and good for terminal issues but if you are providing a radar service across a number of ASRs then 1013 is better.:ok:

[tori chelli]

I believe we are dealing with 2 phrases here for 2 situations:
1) KNOWN trafic which is said to 1000 feet above, 1500 feet below, etc, and
2) UNKNOWN traffic which should be said to be above/below/slightly above, etc..
MATS Pt 1 E (attach) refers
Tori

[2 sheds]

You need to be careful to differentiate between procedures and available standard phrases.

UK MATS Part 1:

15 Traffic Information

15.1 Traffic information shall include the following:
• Bearing from the aircraft in terms of the 12 hour clock (when the aircraft is turning,direction of the unknown aircraft by compass points);
• Distance from the aircraft in miles;
• Direction in which the unknown aircraft is proceeding, e.g. 'traffic is opposite direction/crossing left to right', etc.
• Height information when available, this may include the unverified mode C of unknown aircraft.

15.2 Under some circumstances, controllers may consider it prudent to inform a pilot of other traffic which is separated from his aircraft. In such cases, to prevent any possible confusion, no reference should be made to the actual level of the other aircraft. If necessary, the pilot should be informed that the other aircraft is '(number) thousand feet above/below'.

[tori chelli]

Thanks 2sheds, point taken, but the phrases, which you acknowledge as Standard Phrases, in the part E should be used if applicable, and you're using the available unverified mode C information to make your assessment of "indicating above, below" etc.
Of course we could always have a clear ruling from SRG!:hmm::ugh:
Tori

[NiceVectoring]

Transponder outputs altitude report in 100ft (or 25ft if Mode S and capable) based upon 1013.25 mB pressure. Setting QNH on altimeter, etc, will have no effect on the transponder. This will lead to transponder reported height being different to altimeter report based on QNH. Some of the more advanced radar processing and display systems will QNH convert the transponder altitude report when below transition altitude to give aircraft altitude in feet based on QNH rather than a Flight Level on 1013.25mB
What will be consistant is the difference in height between targets using the same 1013.23 mB pressure reference. So it is probably more correct to state differences in height of local traffic rather than their actual height AMSL that the radar display shows.
oh, and before someone makes a smartarse comment about transponder altitude reports being called Mode C, Mode S equipped aircraft (88%+ of all transponder equipped aircraft) do not use Mode C when responding in Mode S - hence I didn't call it Mode C.:ok:
I'll get off my Mode S soapbox now.........:}

From what I've read somewhere, the transponder doesn't pass an actual level, it passes the current pressure it reads at it's level, whatever it may be. Maybe I've misunderstood something, feel free to correct me.

[2 sheds]

If the Mode C information is unverified, one cannot state that a particular aircraft is actually above or below. I think it is possible to read too much into the application of standard phrases - I suspect that this particular one is a leftover from the days of heightfinders!

[airac]

heightfinders!

Now there was a piece of equipment:D

[RAC/OPS]

ShyTorque, I may have missed the point of your response, but ATC and the radar have no way of knowing what pressure setting the unverified 2400 traffic is on. It would make sense that it is either local QNH, RPS or 1013, but who knows.

I don't like the indicating above/below, and will always say "indicating xxxx unverified."

Widger: I read .......but if you are providing a radar service across a number of ASRs then 1013 is better

as '...providing a radar service for a number of ARS*S....', but that is probably more to do with the day I have had!

[Defruiter]

It was indeed changed because there had been incidents where aircraft under RAS had climbed or descended to the level reported.

I was right then - Thank you for the clarification :)

[ShyTorque]

RAC/OPS,
I'm not sure which response you mean as you didn't make that clear.
I think I agree with your statement - but his encoder and mine work from the same datum, 1013.2, irrespective of the subscale setting in either cockpit.
Sorry, it's been a hard week for me too!

[Radarspod]

From what I've read somewhere, the transponder doesn't pass an actual level, it passes the current pressure it reads at it's level, whatever it may be. Maybe I've misunderstood something, feel free to correct me.

Feeling free :}

The transponder will relate a measured pressure to an altitude based on a fixed "QNH" of 1013.2mB. It will then provide a message in either a Mode C reply or Mode S DF=5 reply to a Secondary Radar with an altitude measured in feet to 25 or 100ft resolution depending on aircraft capability.

[2 sheds]

"...to an altitude based on a fixed "QNH" of 1013.2mB..."

"...to the pressure datum 1013.2 mb..." would be a better way of expressing it. With respect, the reference to "altitude" and "QNH", albeit in quotes, only serves to confuse!

[tori chelli]

2sheds you're putting words into my mouth. The book says "indicating above/below/ etc." for the same reason you say indicating XXXXft in your traffic information.

As nicevectoring points out, the altimeter encoder encodes and transponds based on 1013.2, and any local conversions are done on your radar based on your local settings and Transition Altitude, so irrespective of the pilot's setting, the readings will be equivalent for all contacts.

This shows when a pilot hasn't reset his sub-scale, and is flying (typically) an altitude with (typically) 1013 set and is a few hundred feet adrift from his stated level. A technical bonus which I have used a few times to some pilots' advantage to prevent their further embarrassment :)

Also to re-state Widger's point, this phraseology doesn't date from heightfinding equipment, but from the mid-air at (Delhi??) when the quoted level was taken as a level to descend to and - surprise, surprise - they met. The ICAO guidance thereafter was to refer to relative levels (known traffic) or no level at all (unknown traffic).

Tori

[NorthSouth]

If you are military you are also taught that indicating means unverified and at means it is verfied I wonder how many pilots know that? Precious few beyond the readers of this thread I'd wager. Makes you wonder what the point is...
NS

[2 sheds]

...as long as they also understand that "at" means plus or minus a couple of hundred feet!

[NorthSouth]

then of course there's the question of whether any pilots know what 'verified' and 'unverified' mean.
NS

[Radarspod]

Being nether ATCO or Pilot, I'd like to know:confused:

Is it a case of asking the pilot what height is thinks he is at and checking his response is what the radar is showing?

[Gonzo]

Verified means that the Mode C height information on the radar screen that the ATCO reads off is accurate, to within +/- 200 feet of what the pilot said his level was.

Unverified means that the height information has not been checked for accuracy.

[tori chelli]

radarspod
basically - yes. Obviously unknown A/c squawking 7000 with mode C will by definition be unverified (also referred to as "indicating") because you're not talking to the pilot to effect verification! :)

tori

[ATCO17]

When passing traffic information, the Mil only refer to traffic being "At" a level, altitude or height, when that traffic has been co-ordinated or under the control of the same controller and the Mode C has been verified. With regards to the original post, by inputting the regional QNH into the radar every hour, Mode Cs below the Tansition Altitude are calculated by the computer to the same QNH and displayed as an altitude, ie A30. When aircraft climb/descend through the TA, the Mode C will adjust on the display to a 1013 conversion. Therefore, during periods of high/low pressure, an aircraft displaying FL060 can in fact be at the same level/altitude as an aircraft at 5500 ft on the regional QNH.

[RAC/OPS]

When passing traffic information, the Mil only refer to traffic being "At" a level, altitude or height, when that traffic has been co-ordinated or under the control of the same controller and the Mode C has been verified.

What does the Mil do with Mode C associated with another unit's discrete code, if no coordination received?

[Spitoon]

basically - yes. Obviously unknown A/c squawking 7000 with mode C will by definition be unverified (also referred to as "indicating") because you're not talking to the pilot to effect verification! Strictly speaking it simply means that the mode C has not been checked for accuracy by the controller that you are speaking to (or, in the UK and subject to certain conditions, a previous controller that has handled the aircraft on that flight). It is immaterial whether the controller is talking to the pilot. There are many occasions when I might talk to a pilot but leave him/her on 7000 and not check the mode C - just to be contentious, I'll also note that I might identify the aircraft on the 7000 squawk even though I don't subsequently provide a radar service. I think the good book still allows that........

[tori chelli]

"I might identify the aircraft on the 7000 squawk"

Interesting idea Spitoon,

what method of ident would you use...not a secondary method I hope? :eek:

'Good Book' page 1-5-6 para
4.1.c) Observing an IDENT feature when it has been requested... Aircraft
displaying the conspicuity code are not to be identified by this method.

[Spitoon]

Position report, of course.

That's assuming you've got primary.

[BurglarsDog]

For RAC/OPs.
If an acft is wearing a validated mode 3A code then the mode c displayed is deemed by other viewers as verified - so the mil would describe its level as "AT" even without coordination. If the controller working that traffic notices an error in the acfts mode C it is normally turned off - unless mode C and A are linked as in some older kit and cant be turned off without also turning off the Squawk. Then the controller should pass the word down the line to adjacent units/ viewers that the mode c is corrupt.

DogGone:ok:

[Riverboat]

Well I must admit that it is a bit more complicated than I had thought! I do dislike being told that an aircraft is "2000 ft below" when I am in descent, because I suspect that I was higher the last time the ATCO looked at me on her radar screen, and therefore the other aircraft isn't 2000 ft lower at all.

It is the uncertainty that I don't like, and I'd certainly feel happier if I was told that the aircraft was "at 3000 ft" whether verified, unverified, or "at". Then I would feel I knew where it was, +/- 200 ft or so.

However I am not knocking the service, which is usually very good and only making a pilot's subjective comment. Not many other pilots have joined in with my view, so maybe it is not widely held.

I do feel that we sometimes make quite odd changes to the way things are said because "something once happened". I know we have to learn from experience, but I feel we do rather overdo it at times.

[mr.chaps]

Riverboat

You could level off until you are clear of the traffic and then continue with your descent.

That way you wont have to do any of those nasty sums!:ouch:

[NorthSouth]

Not if you want to remain in VMC and levelling off would involve entering cloud. If I was in that position I would seriously consider requesting a RAS cos I would have lost all possibility of seeing the traffic.
NS

[Pierre Argh]

Whilst all in favour of clear, concise and helpful R/T the problem comes when reported height information is based solely on SSR Mode C. I think the verified/unverified part is a red herring - the following applies whether verified of not.

As many above may have already said, the Controller is using a display where all Mode C information is converted to the same pressure setting(s). It is therefore deemed better for the Controller to relay relative height information than the observed height readout.

For example: Let's assume you're in receipt of RIS, decending through 2800' to 2000' on an QNH of 983mbs. The controller has unknown traffic indicating 3000' on the display. This height readout has been corrected to the SAS so is actually reading 900' high (1013-983 = 30. 30x30=900). If you were told the a/c was at 3000' you might be fooled into thinking "I'm below that and descending, it isn't a factor", whereas in truth you're still descending towards the other traffic.

To avoid this situation therefore, the Controller should compare your SSR height read-out (that has also been converted) with that of the other a/c and only pass relative height information i.e. "indicating 700' below you". True there will be a minor time-lag due to SSR data-transmission/display update rates/RT time - but ISTM that is still safer than giving a completely false impression?

[tori chelli]

Pierre
I believe you're 1/2 right...the levels shown on the screen ARE transmitted on 1013.2 AND converted to the same datum (below TA) which will be whatever is input into your radar display/system.
Some use 1013 (scary) and some input their local QNH. If QNH is input, and we are talking at or below TA (which in your example of 3000' you are), then unlike in your example, the mode C readout will be relevant, i.e. 2800ft descending will be below unknown traffic @ 3000ft...and better still, this will be based on 1013.2 set in the encoding altimeter and not dependent on the pressure set by the pilot on the sub-scale. WYSIWYG

[dscartwright]

With regard to the "Traffic XXX feet above/below you", the useful part of it for VMC flight is the "above/below". Over the years I've had plenty of controllers say: "Traffic below you in your 10 o'clock". So long as you know to look up or down, and vaguely what direction to gaze in, you're most of the way to spotting it.

David C

[Pierre Argh]

torichelli is, I suggest, being a bit pedantic - factually correct but over emphasising the wrong point - let's take it up a couple of thousand from 3000 to FL50? (In my expereince I have never seen/worked at a unit that inputs QNH on the grounds that it is inviting an input error - but that's not to say there aren't units that do?)

DScartwright has hit the nail - such traffic information includes advisory height information, it isn't going to be spot on accurate! all that is surely important is a guide whether to look above, well above/ below, well below?

[2 sheds]

"I think the verified/unverified part is a red herring"
(Still can't get the "blue panel" quote system to work!)

Hardly a red herring - the inclusion of "unverified" in the case of most unknown traffic is saying that there is a chance that the height information could be completely wrong.

[Pierre Argh]

the inclusion of "unverified" in the case of most unknown traffic is saying that there is a chance that the height information could be completely wrong Totally True, but not relevant to the question posed at the beginning; which would apply whether reporting Verified or Unverified traffic i.e. whether to call the height indicated or relative position, hence it is something of a red herring in this instance surely?

(Politely) Get back in your shed - either of them!

[tori chelli]

Pierre

"In my experience I have never seen/worked at a unit that inputs QNH"...in 4 units over 21 (radar) years, that's the only kit I've ever worked with :\

"DScartwright has hit the nail - such traffic information includes advisory height information, it isn't going to be spot on accurate! all that is surely important is a guide whether to look above, well above/ below, well below?"...isn't that what the standard phrase for unknown traffic in the MATS Pt1 says? as per my original post on this thread? :D

Tori