Squak Codes

[PostmasterGeneral]

So what's the deal? How are they assigned? Randomly generated in a top secret Nav Canada mainframe computer deep underground somewhere? Or is there a rhyme and reason to how they're assigned? I've always wondered.

Are they assigned based on area, can there be duplicates in Canada? North America? Why will ATC have you change codes sometimes? When someone does change a code, or when asked to ident, what does that "look" like to the controller on his scope?

Thanks for satisfying my curiosity!

[andy_mtl]

I remember this summer calling Montreal flight planning and asking for my daily code,
And again for the 8th day in a row I got a code starting with 45xx
So I asked the lady why, and she told me most Vfr assigned codes start with 4.

Locally I was lucky enough to be able to go up in Gatineau Fss often and the supervisor there
Has shown me quite a few things.

You can arrange to visit a tower/Fss/terminal (depends where you are)
It's very fun to see and get an idea of what they do.
Gets you to respect them much more after.

Andy

[hydro]

can there be duplicates in Canada? North America? Why will ATC have you change codes sometimes? When someone does change a code, or when asked to ident, what does that "look" like to the controller on his scope?

The computer assigns a number from a predetermined block of available numbers. Certain blocks may me assigned to different areas or uses.

Yes there can be duplicates in the sense 2 active aircraft will have the same code, but the flight plan system per FIR/Centre should only have one plane per code, which is the main reason ATC may ask you to change from one discrete code to another when going to a new centre's airspace. Edmonton may have someone on a code. Montreal may have someone else on same code. No problem. As they cross the country in Winnipeg's airspace the computer someone needs a new code so the radar system correlates correctly.

With an ident, the target flashes white for a few seconds.
When someone changes their code, the normal target changes to uncorrelated (just a target with the new code, but no aircraft info), for a couple seconds, and then the computer processes it and correlates the new squawk code with a flightplan in the system and looks normal again.

[PostmasterGeneral]

Thank you for the answer. How does it work when trying to view an aircraft's flight plan for example? Are you able to click on that aircraft and view information about it's route? Man, I really ought to go for a tour of a facility one of these days!

[Driving Comet]

Thank you for the answer. How does it work when trying to view an aircraft's flight plan for example? Are you able to click on that aircraft and view information about it's route? Man, I really ought to go for a tour of a facility one of these days!

The Towers get a auxiliary display system for our radar that has a lot less functionality that the IFR controllers have. Our primary radar display is what they use as a drop down backup should their primary screen (Csit I believe) fail. The tower radar we can double click on a target and it will pop up and show all the information like route, type, etc. We can also set presets to show certain information depending on who the plane is talking to. For example, if you're talking to buttonville tower, they "take" the tag and it shows "KZ" on the radar. I can set my display so that anyone talking to YKZ tower only shows aircraft type and speed and altitude.

[PostmasterGeneral]

Thank you for the reply! How do callsigns work? I'm assuming it just comes with experience that flight "MPE 732" is "Empress 732" and so on. Do you only see the MPE (or is it 5T?) and have to know what to call them? Reason I ask is not so much for the ACA and WS flights, more for the weird ad-hoc military stuff that I hear sometimes from either the USA or overseas. Sorry for all the questions but this stuff really interests me.

[Driving Comet]

Thank you for the reply! How do callsigns work? I'm assuming it just comes with experience that flight "MPE 732" is "Empress 732" and so on. Do you only see the MPE (or is it 5T?) and have to know what to call them? Reason I ask is not so much for the ACA and WS flights, more for the weird ad-hoc military stuff that I hear sometimes from either the USA or overseas. Sorry for all the questions but this stuff really interests me.

Empress is MPE. It's ICAO, not IATA that we use. You get use to the common ones. The uncommon ones we can look up or sometimes it's in the flight strip under remarks. We occasionally also get mandatory readings that will advise of new call signs, such as when Seneca got a call sign.