Sqwark ident

[Camel]

When asked to sqwark ident by ATC, is there a set time, how long should the button be pushed ?

 

 

[Guest Maj Millard]

I tend to hold it down for around 5 seconds, don't know what the book says about it...........Maj...

 

 

[Guest Andys@coffs]

its irrelevant. Once pressed your transponder and the other end will do the job asked. The speed of rotation of the radar head on the ground determines how often the radar paints your aircraft (and the SSR Tx/Rx head requests a Tx from your transponder) Short range radars spin faster, long range slower. Unless you know the range of the radar(s) that will be painting you you have no idea of how long the ident button needs to be pressed so that is taken out of the equation as info the PIC generally wont have.

 

And that's just SSR (Secondary Surveillance Radar or IFF depending on civilian/military basis) that is attached to ground radar stations. When you then consider airborne Tx requests (RAAF Aircraft or TCAS) it really isn't something that most pilots should know and be concerned about.

 

However for a definitive answer look in your transponder users guide (or google for a copy of that)

 

Andy

 

Andy

 

 

[metalman]

Very handy Andy Andy

 

 

[Camel]

Thanks Andy, very informed answer, I'm going to keep doing what I've been doing, never been any complaints.

 

 

[facthunter]

Your aircraft "paints" if you are high enough. and reflect enough. The ident is for that purpose alone. The screen would have a lot more clutter if the ident was continuous. Sometimes you get a heading change instead. That may be for "identification and separation". Nev

 

 

[Patrick Normoyle]

A few misleading ideas here, once the "ident " function is activated on the aircraft transponder we will see the effect on the radar for as long as the transponder is emitting the ident ( typically 10 sec plus ), the SSR radar only receives there is no real transfer of data, this has nothing to do with primary radar at all.

 

Camel, check the manual ( someone else idea but a good one) it will tell you how long you need to press the ident button to activate the feature and it may tell you how long it transmits for.

 

 

[kgwilson]

Sqwark is actually Squawk. Just replace the R with a U and rearrange the letters a bit. Close but no cigar.

 

 

[Patrick Normoyle]

Thanks for the spelling lesson !

 

 

[Guest Andys@coffs]

A few misleading ideas here, once the "ident " function is activated on the aircraft transponder we will see the effect on the radar for as long as the transponder is emitting the ident ( typically 10 sec plus ), the SSR radar only receives there is no real transfer of data, this has nothing to do with primary radar at all.Camel, check the manual ( someone else idea but a good one) it will tell you how long you need to press the ident button to activate the feature and it may tell you how long it transmits for.

Patrick, I beg to differ. I have formal avionics technician training and spent quite some time in Melbourne learning about IFF and SSR .

 

You are right that primary radar and SSR are different things....but the SSR Antenna head (usually 2 to 3 degree directional beam width) is generally on the same radar head as the primary radar and is pointed in the same direction as the primary radar so that ATC or the ATC system can correlate primary returns and SSR returns. The SSR Antenna on the primary radar head transmits a transponder interrogation request (1030Mhz) , and then listens for the transponder response (1090mhz). Peoples transponder triggers when the SSR head (via the primary Radar head) is pointing at them due to the narrow beamwidth of the SSR antenna.

 

When someone pushes the indent button a single bit in the transponder response message is set and at the receiving site the ATC computer system chooses how long and what to show when the ident bit is received and decoded. The receiving end will display for as long as its setup parameters choose to display which may be completely decoupled from how long the transponder chooses to have the ident bit set in the messages it responds to.

 

Patrick SSR definitely isn't one way only and there definitely is transfer of data. Details of the types of interrogation requests that can be sent can be found here http://en.wikipedia.org/wiki/Secondary_surveillance_radar Furthermore mode S extended squitter (ADSB) has the potential to contain a great deal of data inc lat/long alt speed ground track, unique Serial number etc.

 

It may well be that in the fullness of time ( or even where no primary radar exists today such as inland areas) the current connection between SSR and Primary radar that exists today will disappear, the inclusion of all the ADSB data elements means that tieing ADSB which is the natural evolution of SSR and primary radar is not necessary at the primary radar head and the SSR interrogation request will become Omni directional rather than narrow beamwidth as it is when tied to primary radar.

 

Andy

 

 

[Mriya]

Well described Andy. As a LAME who has done the relevant CASA Basic exams for transponders and getting close to applying for the licence rating, your description of radar systems is well presented and displays an in depth knowledge of the various systems in use today.

 

The only thing that I would add which takes us back to the original question regarding time needed when pressing the ident button is to note that when performing a AD/RAD/47 check one of the items tested is to confirm that the IDENT bit response continues for approx. 20 secs following operation of the ident button. Therefore holding the ident button makes no difference to operations as once selected it latches in the transponder and sends the IDENT bit when interrogated for the next 20 seconds or so anyway.

 

 

[Guernsey]

I have a Crow who comes in from the north east every morning and squawks ident and I usually respond "yea, yea. I heard you".

 

Alan.

 

 

[skeptic36]

I have a Crow who comes in from the north east every morning and squawks ident and I usually respond "yea, yea. I heard you". Alan.

That's nothin, I have several crows that come in to the fig tree from all directions squarking all sorts of stuff and I usually respond with

 

 

[frank marriott]

What confuses me is why should you be asked to squawk ident when flying OCTA. If flying in CTA it should be covered in your endorsement. ??????

 

 

[kaz3g]

What confuses me is why should you be asked to squawk ident when flying OCTA. If flying in CTA it should be covered in your endorsement. ??????

Usually so that ACT can separate your return from another one probably flying an IFR plan.

 

Kaz

 

 

[mothra]

If you are OCTA you wont be being separated , more likley youll be being passed as traffic to an IFR.

 

If youve called up for nav assistance youll be asked to ident so they can be sure where you are to start with.

 

 

[frank marriott]

Interesting, just I have never struck it, as a matter of fact I can't recall being asked even in CTA since the introduction of mode C.

 

 

[Guest Andys@coffs]

And with ADSB well entrenched its a practice that will absolutely disappear completely. ADSB has a unique serial number allocated per transponder and any response by the transponder to a challenge will always carries the unique transponder S/N so no need for ident function which when all said and done was merely a human initiated way of differentiating between 2 close SSR returns....

 

Squawking will be limited to crows ......and forums it seems

 

Andy

 

 

[Mriya]

Once again Andy is right. ADS-B and Mode S will make IDENT a redundant feature. However in the meantime ATC can request it allowing them to positively identify the various Mode C traffic that shows up on their radar screen. I have had it happen once as I was joining the Kilmore VFR lane at Sugarloaf in a RAAus Tecnam. I had just made a position advisary call on the area frequency and Melbourne Centre then requested me to IDENT. It turns out I had the transponder set to Mode A, so once they positively identified me they advised me to switch to Mode C. With that done we were all happy. My understanding is that ATC would always use the ident before attaching your rego to a 'blip' on their screen to avoid any possibility of mislabelling you in their system. Most of the time as uncontrolled traffic they are content to leave you be, but they always have the option of attaching your rego to their display and if they decide to do this they need to know which 'blip' is you. Once you have Mode S installed your aircraft identifier is coded into the reply sequence and so they can positively identify you without the manual IDENT process.

 

As an aside, if you are in the Melbourne or Brisbane areas you should keep an ear out for an opportunity to visit the respective Airservices Australia air traffic control facilities via your local club or flying school. I tagged along with a group from our local flying school visiting the Melbourne facility and it was a most informative evening. You get to see in person the 'voice' on the other end of the radio and come to appreciate the resources that are available to help you get back on the ground safely, especially if you manage to get into a 'pickle'. I'd recommend it to all pilots as it 'demystifies' the whole system and gives you confidence that lots of help is available if you need it one day. Airservices Australia was also happy to host the event as it ultimately makes their job easier once pilots know the processes and systems and work with them rather than against them.

 

Talk to your flying school or aero club and arrange a visit.

 

 

[Jabiru Phil]

Interesting, just I have never struck it, as a matter of fact I can't recall being asked even in CTA since the introduction of mode C.

Frank

 

I was about to divert around c t a Townsville on my way to Horn Island a couple of years ago and was invited to overfly.

 

I accepted and the controller asked me to squark and ident. Not having done it before, it took me a while to find the ident button.

 

Just gave it a push and the controller said that she had me identified.

 

I thanked them for allowing me to transit, saving about 15 minutes. Controller said he can't understand why we are compelled to deviate when all is quiet. I had to change to two freq during the overfly.

 

I have a texts mark on the ident button now, just in case.

 

Phil

 

 

[ben87r]

"What confuses me is why should you be asked to squawk ident when flying OCTA. If flying in CTA it should be covered in your endorsement. ??????,

 

G'day frank. We get asked to to do it nearly on a weekly basis on a busy VFR route (SUB SPR/ WRR DMW). Helped me a few times with separation from other VFR OCTA

 

 

[frank marriott]

No big deal, just I have not came across it for some time.

 

Ben, the answer probably lies in the low density traffic up in NQ, when you give a position & request clearance generally you are the only aircraft in the immediate area and at your reported altitude.

 

Phil, your case is interesting. For CTA I always submit a flight plan so you are then expected at the particular position and height. (Plus you are given a discrete code which identifies you anyway - as opposed to unidentified 1200 traffic)

 

But in any case, no problem just push the button if requested to do so. Everyone should be made aware of what is required.

 

I remember when transponders were being used but not mandatory at YBTL you would be given heading changes for identification if operating an aircraft without a transponder. Maybe procedural but we always thought it was a hint that transponders were preferred - especially when you were the only traffic for miles in any direction (even after giving a VOR/DME position)

 

 

[DWF]

A transponder is the device in your aircraft that replies to an interrogation signal from an ATC Secondary Surveillance Radar (SSR). There are a number of transponder modes. The most common transponders used in RAAus and GA aircraft can only operate in mode A (replies with the code set on the aircraft's transponder - usually 1200 for OCTA aircraft) and mode C (replies with the code set on the transponder plus the aircraft's Flight Level i.e. level reference 1013.2hpa).

 

When an aircraft operating OCTA and squawking 1200 Mode C (the norm) is within SSR range the controller will see a symbol on the screen with a tag attached showing 1200 and the aircraft's altitude (from information send by the transponder) plus the aircraft ground speed and track (computed by the radar system). The controller knows there is someone out there but doesn't know who it is.

 

Before the controller can give the aircraft instructions (should this be required) or traffic information the aircraft must be POSITIVELY identified. The controller has a number of ways of doing this. The easiest and quickest way is to have the aircraft "Squawk Ident". When the pilot presses the 'Ident' button on the transponder it adds another piece of information to the return signal telling the radar system the IDENT button has been pressed. This is usually indicated to the controller by making the appropriate aircraft symbol flash on the screen. The controller will usually tell the pilot "(insert callsign here) Identified, ......" and then provide information or instructions.

 

[This is a general outline of how the system works - there are a number of variations, conditions and exceptions.]

 

Other methods of identifying an aircraft on radar can be by assigning a discrete transponder code to the aircraft or assigning a heading change to the aircraft and checking that the appropriate symbol changes direction to that specified.

 

When departing Jandakot and tracking to the east via Armadale (an often busy area of inbound and outbound routes restricted by CTA steps) I usually call Perth Radar giving my position and altitude and ask for a Traffic Advisory. The usual response it to be asked to Squawk Ident and when identified the controller often has significant traffic to pass to me.

 

If you get close to a CTA boundary or step you may also have ATC call "Aircraft (at such and such position) advise callsign". If you are transponder equipped and squawking (an SSR return symbol will be on their screen), and respond to ATC, they will usually ask you to Squawk Ident.

 

Mode S transponders are more sophisticated and expensive than Mode C transponders and are usually not found in RA-Aus aircraft. ADS-B is not strictly speaking a transponder and again is not usually found in our aircraft.

 

Does that help?

 

DWF (ex ATC - quite a while ago now)

 

 

[Mriya]

Mode S transponders are more sophisticated and expensive than Mode C transponders and are usually not found in RA-Aus aircraft. ADS-B is not strictly speaking a transponder and again is not usually found in our aircraft.

This statement will quickly become inaccurate if it hasn't already in that come Feb 2014 all new transponders being installed will need to be Mode S.

 

 

[motzartmerv]

Controller said he can't understand why we are compelled to deviate when all is quiet. I had to change to two freq during the overfly.

Because regardless of being invited, or quiet, without a PPL (minnimum) and an aeroplane that complies, its illegal and is a breach of CTA.

 

Just a general statement, not aimed at your situation.