Conspicuity squwark
 

Hi All,

I'm trying to understand a bit more about the circumstances in which a conspicuity squwark is given rather than a discreet squwark.

On the level of a basic service, is there any difference in the service level if you have conspicuity squwark as opposed to a discreet squwark?

What's the correct RT to request a discreet squwark instead of the conspicuity?

Many thanks all.

D

Firstly, "squawk" is so spelled. There is essentially no difference in service provision on a basic service for discrete or conspicuity codes. With a discrete code you will be identified, but that is it - there is still no surveillance derived traffic information (or at least, there shouldn't be). If you want a traffic or deconfliction service then you have to be identified and you will probably be given a discrete squawk. Note that transponder carriage is not mandatory for these services and the controller can identify aircraft using the PSR if required.

Bear in mind that some units have conspicuity codes that look like discrete codes - just one of their octal block is allocated for basic service use (or whatever) and may be assigned to more than one aircraft. When mode S really takes hold, then the aircraft ID will be taken from the downlinked parameters (already is in some units) and the flight may be identified on surveillance equipment this way, with some provisos.

I'm not sure why you would want a discrete squawk particularly, and there is no standard RTF that I'm aware of for this purpose. A controller issuing a squawk will only ever give an appropriate one (mistakes aside) so I think maybe you're over-thinking this one. Has there been a specific instance that has sparked this question?

Many thanks reportyourlevel, that's very clear!

I was given a conspicuity squawk recently for the first time in 4 years, so got to thinking about the differences........

Why would you want a 'discrete' squawk in lieu of a 'conspicuity' squawk on a Basic Service? A Basic Service is not a 'surveillance' service. Discrete squawks aren't issued on request, they are issued in accordance with ATS procedures, not just because someone fancies one. They might be used for internal or inter-unit identification. Some squawks are allocated by units which are not equipped with SSR but the code is of value to other units which have SSR.

Imagine a discrete squawk is the controller lending you money. You might get five bob, or you might get a quid. He'll sure as hell want it back at the end. The important thing to remember is that on a Basic Service do not expect to be issued with specific traffic information. The SSR code allocated by ATS is of no concern to the pilot.

Conspicuity squwark
 

ATCOs lend money?

Conspicuity squawks are normally issued by non-radar units so that adjacent radar units can see who's talking to who. That way if an aircraft was to infringe controlled airspace, the radar unit will know who to call straight away rather then ringing round the units.

dabinett
 

I don't know the depth of your interest but if you want a good read I suggest the following:
NATS | AIS
click on "IAIP"
left hand column click "ENR Index"
click "1.6"
Hope that is useful.....rgds

I have always understood the primary purpose of a conspicuity squawk to be to let those operating adjacent zones know who you are in radio contact with.

^spot on. Doesn't even have to be validated or verified so be careful.

Direct link to the AIP page mentioned above.

I'm not sure I agree entirely. Yes, they do allow for easier tracing of an infringing flight but that is not always possible (e.g. in the case of 7000) nor is it, I believe, their primary (ho hum!) purpose.

Without a transponder (or a transponder set to STBY) there is no SSR plot on the controller's situation display. This means that the aircraft is being tracked by the PSR only and can be lost for various reasons (e.g. clutter or poor coverage to name only two). Selecting the transponder to ON (ideally with ALT) allows the controller to see an SSR position symbol on the surveillance display. However, it will show up with whatever code is selected on the transponder. Obvisouly, some flights are allocated a unique, discrete code and confusion may occur if a second flight happens to randomly select the same code. (Remember, not all flights need be working an ATS unit so they may not be issued with a code themselves.)

So we need another code which allows you to select your transponder to ON and therefore be more conspicuous on the situation display. You also become more conspicuous to any aircraft fitted with ACAS. Hence conspicutiy codes - by far the most common being 7000. Some units find it useful to have their own conspicuity code and these codes do, indeed, serve the purpose you both state, although looking through the AIP entry above many of them are surveillance equipped. Listening squawks can also be very useful here.

Again, I refer to the AIP link above, which states: "Controllers are reminded that codes annotated with * are used for conspicuity, co-ordination or special purposes and the Mode A and associated Mode C pressure-altitude reporting data must be considered unvalidated and unverified." So it's not that they don't have to be validated and verified, it is that controllers must not treat them as such (even, in my understanding, if they have issued them and undergone the procedures to validate and verify). That is not really a pilot problem though and, being honest, I suspect many controllers would apply a more liberal, if incorrect, interpretation of the rules on this.

I would like to point out that there is a difference beteen different conspicuity codes.
In EBBU FIR, 7000 is used by VFR flights. This use is very different from 1000 which is used by a/c operating in Mode S declared airspace. 1000 means that aircraft will be identified by using the Mode S a/c ID instead of a discrete code.
UK airspace is not Mode S yet so the 1000 code would not be used.

P.s.: just read through the relevant section of the UK AIP and it seems they do not see 1000 as a conspicuity code... Seems we have a different definition for 'Conspicuity code'

Probably not a different definition, just a different assignment of codes.

But don't worry, EASA will sort it all out for us.