what do you understand by "unverified" ?

[Legs11]

:O Hello all.

As an ATC providing traffic information to you, when I tell you that another aircraft's level is "unverified", how many of you know what I'm talking about?

I would appreciate any comments you might have as I sometimes wonder about the understanding of this term.

Ta very much:ok:

[topcat450]

I'd take it to mean you didn't know it's altitude....so if it was in my general area I'd keep an eye out & if spotted I'd let you know if it was above me or below:confused: simple as that innit?

[nasib]

That you can see the aircraft on radar, that they are squaking with mode charlie but that, since you are not talking to that aircraft, you cannot guarantee that the altitude readout is correct.

Nasib

[Timothy]

I've always taken it to mean as nasib says...you can see Mode C, but you have no idea if Mode C (a notoriously error and failure prone bit of kit) is telling the truth.

You assume that a pilot looking at his altimeter (a) is telling the truth (b) has an accurate altimeter and (c) has set the sub-scale correctly, and is therefore in a position to verify the C readout.

You are probably right to trust the pilot above the Mode C capsule...but maybe not totally :)

W

[Whipping Boy's SATCO]

The controller is telling you that he cannot confirm the Mode C information of a particular aircraft to be within acceptable tolerance (+-200ft). Controllers who can validate a particular code (Mode A) as being allocated by another ATC unit that can be expected to be controlling ac within that piece of airspace can also assume that Mode C information has been verified.

[Chilli Monster]

WBS - I think the question was aimed at pilots who aren't ATCO's ;)

[FlyingForFun]

Ok - so now we all know what "unverified" means, thanks to some good answers on this thread.

Next question: you're flying along at 2000', receiving a RIS, when ATC tell you that you have "converging traffic in your 10 o'clock, left to right, 2000' unverified". You can't see the traffic. What do you do? Do you act any differently to if the traffic's altitude had been verified?

How about the same scenario, but the unverified altitude is 500' below you?

FFF
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[IO540]

FFF

I think you act the same. All you can do is keep looking for it, as usual...

But if I was in IMC, I would climb or change heading. The safest assumption is that the other man's transponder IS working.

[FoxRomeo]

Just a short add-on from this side of the Channel.

Everything we (controllers, FIS, RAFIS, etc..) say goes onto tape to be examined after an incident. Things we know for sure, because they are confirmed, we tell you (pilots). Things we got through pilots reports, we tell you as reports. Things that are not verified, we tell as such.

For example: When issuing traffic information, I will indicate how I received the altitude information. E.g. "... altitude reported 2000 feet ..." or "... radar indicates altitude 2000 feet ..."

I'm usually the one surviving the incidents, so I get to answer the attorneys questions. That's the way it works over here, it can't be much different over there.

Never the less, given the technology used nowadays you can take all of those values as sufficient for VFR operation.

Keep them in the air, FR

[bertiethebadger]

FFF,

I'd probably ask for the range of the converging ac & also listen to see if the ATCO is warning them of me.

Seeing as I'm on the right, if it wasn't immidiate (or there abouts), I'd see if the other ac is going to give way. This is all time dependant.

If the ATCO was not in contact & the threat was imminent, of course, I'd have to manouver.

As it's my right of way, I'd let them maouver 1st as I wouldn't want to match there actions. If not, I'll move.

[FlyingForFun]

Bertie,

Very good point about you being on the right - for the sake of the example, I probably should have made the traffic in your 2 o'clock, right-to-left ;) However, I will always give way to traffic, even if it's on my left, unless I can clearly see that he has seen me and is taking avoiding action - I know there's a very good chance he hasn't seen me.

That aside, the point of my question was that you don't have the other traffic in sight. You know where he is laterally, but the only height information you have is unverified.

As IO540 says, the safe assumption is that the other guy's transponder is working, and it's worth taking some avoiding action (especially if in IMC) if the unverified altitude is the same as yours.

More interesting, though, is the case where ATC say he's 500' below you, unverified. What if his transponder is 500' out? Would you take avoiding action? Personally, I wouldn't... but I do sometimes wonder whether I should.

FFF
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