IFR: whom do you talk to?

[chephy]

I'm in process of obtaining an IFR rating, and am fairly confused by the ATC procedues. I understand that an IFR aircraft must obtain ATC clearance before entering any controlled airspace, and I guess should remain in contact with ATC while in the airspace, but in some cases I don't understand where to look for appropriate ATC frequency.

Example 1: suppose I take off on an IFR flight plan from my buddy's grass strip, which is totally Class G. I do that without talking to anyone (other than the FIC guy on the phone with whom I filed a flight plan, that is). My plan is to intercept a Victor airway. But as far as I can see, there is no frequency associated with a Victor airway on charts and publications I'm familiar with (VNC, VTA, LO Charts, CFS). I see some PAL frequencies scattered around LO charts, but there don't seem to be any clear boundaries for them. Whom do I call?

Example 2: There are many uncontrolled aerodromes with control zone (Class E) around them, with something-or-other radio providing air traffic services. However, to my understanding they are not considered ATC (since they can't actually issue instructions and clearances). So whom do I contact to enter that airspace?

Example 3: I get a powerful little plane that can go above 12,500' ASL, and decide to venture into Class B. Frequency?..

A second question I have is concerning collision avoidance while IFR. How can an IFR pilot ensure collision avoidance in IMC in Class G??? What about Class E, if the weather is marginal, and there is a possibility that unannounced VFR traffic might be in the area?

Thanks in advance for any help. Excuse the naivete of my questions; even as far as VFR ATS procedures go, I'm not as great at know what they are exactly because the rules and guidelines seem to be so vague in many cases (e.g., what exactly is the definition of flight following and who is required to provide it, if anyone; and why I'm talking to terminal sometimes during flight following even though I'm below their airspace and have no intention of going higher; and who exactly are the people on a new frequency that's not on any charts or publications; and what's the difference between Centre and Terminal; and why do I at times get told "radar service terminated" and no further instructions on whom to contact, when all of Southern Ontario has radar coverage; and what's with all the RCOs, DRCOs, FISEs, FICs and FSSs?.....)

[FL001]

Ok,

Example 1: You don't need a clearance to take off or fly around in Class G airspace. You are on your own. However, you need a clearance to enter controlled airspace. You can get a clearance before you take off over the phone if necessary. Otherwise, you check for the nearest airport to you with a PAL and you call them prior to entering their airspace. They all connect to the area control center for your region and they will know what to do with you.

Example 2: You are wrong here. Class E is controlled airspace for IFR operations. Even airports with an FSS or airports with a tower that is closed at night will be Class E airspace. This means that prior to departure on an IFR plan you will need to get a clearance or at the very least a VFR departure. There will be a frequency for the unattended airports that will connect to the area control center or the nearest FSS that can relay a clearance to you. If you enter Class E airspace at an airport with an FSS, then you are still controlled and kept separated from other IFR traffic. The FSS is not the controlling agency however.

Example 3: This depends on where you are and gets a little fuzzy. Up north, you can be as high as FL270 and not be in controlled airspace. In the south near major airports there will be the Class B above 12'500. Class B is not everywhere above 12'500 in Canada. Just near the major centers. You call the controlling agency for that airport the Class B is designated around and get your IFR clearance as you would anywhere else, or if you are VFR they let you in subject to you not being in conflict with any other IFR traffic. Who you call depends on the airport and how the airspace is divvied up but will be either be a terminal frequency or a center frequency.


As for your last question, ask yourself what is Class G airspace. ATC has neither the responsibility nor the authority to tell you what to do in Class G. You are on your own. This means you provide your own separation from other traffic even if you can't see it. How do you do that? 126.7, 123.2 and the MF or ATF frequencies of nearby airports will sort this out for you and your eyes as well when you pop out of the clouds. Just be aware that not every plane in uncontrolled airspace will have a radio and generally people with airplanes who live in areas of Class G airspace do some pretty strange things. I know of one fellow who didn't have a radio or any navigation instruments and he used to bomb around in clouds all the time to build his IFR time even though he didn't have an Instrument rating. Smart? No, but this shit happens more than you might believe.

Last thing. "Center" is the frequency for a particular region that planes will be using, likely in cruise. "Terminal" is only used at major airports with the need for a Terminal frequency.They control inbound aircraft descending to the airport or control lower aircraft cruising through the area that aren't at an altitude that "Center" would be responsible for. For incoming traffic, Center would hand off to Terminal, Terminal would hand off to Tower. For outbound traffic, its the opposite.

Hope this helps

[ahramin]

Hello chephy. It sounds to me like what you need to to is hop in an airplane with someone who knows their stuff, go flying around and ask all these questions. Such people are not necessarily easy to find but ask around, you might get lucky.

1. First place I would look for a frequency is your LO chart. Pick the closest PAL and call them. If it happens that you are under a sector being controlled by someone else, they will give you the correct frequency for that sector. If there is an airport nearby which is in the CAP, look at the departure frequency for that airport. Lastly, you can call the centre and ask them the frequency for the sector above that strip. While you are on the phone, you can also get your clearance on the ground before you depart in most cases.

2. If the airport is served by an FSS, the FSS will get the clearance for you and then forward it to you. On your initial call up tell them you are IFR to cabc. They will call centre, get the clearance, then read it to you. Read it back just like any other clearance and you are in business.

3. Venturing into class B will be seamless unless you are coming at it sideways, in which case the methods listed in 1 will work. Vertically you don't need to worry about it, if a handoff is required, you'll get it.

I haven't got my mittens off so I could be wrong, but I think this is question 4, not 2. As for IFR in class G, it's the big sky theory, complemented with timely and good radio work. The frequency for this is 126.7 and the local airport frequencies when departing and arriving. Please not that when exiting controlled airspace into uncontrolled, you should make your 126.7 call before you get into uncontrolled airspace.

VFR flight following is a value added service provided if you want it. If you are VFR in class E or G and do not want to talk to a controller, feel free. Personally I always take this service when available.

If you get handed off to a frequency and you can't figure out where it originated, you can ask that controller and they will let know you. I don't usually worry about such things unless it is an area I use frequently.

Don't worry about whether you are talking to centre, terminal, departure, or arrival. Would a rose by any other name ...?

"Radar Service Terminated" when VFR means they are no longer following you on radar, and therefore are not flight following you anymore. When IFR it is different.

You should not be flying around VFR or IFR if you do not know what RCOs, DRCOs, FISEs, FICs and FSSs are and how to use them. Every private pilot should understand these thoroughly. Get a copy of the CFS and download the AIM and start reading.

[chephy]

Thanks for the answers!

Hello chephy. It sounds to me like what you need to to is hop in an airplane with someone who knows their stuff, go flying around and ask all these questions. Such people are not necessarily easy to find but ask around, you might get lucky.

Well, that's sort of what I'm doing with my instructor, I suppose, but this is all on an ad hoc basis, so to speak. I am looking for a more general sort of picture because all the flying I do is around a major centre, so that knowledgeable person can't really help me out with procedures that would apply in more remote ares.

1. First place I would look for a frequency is your LO chart. Pick the closest PAL and call them. If it happens that you are under a sector being controlled by someone else, they will give you the correct frequency for that sector. If there is an airport nearby which is in the CAP, look at the departure frequency for that airport. Lastly, you can call the centre and ask them the frequency for the sector above that strip. While you are on the phone, you can also get your clearance on the ground before you depart in most cases.

So there is no publication that lists all of that stuff for you and no sure way to know this without talking to someone, in other words? Aww, too bad.

2. If the airport is served by an FSS, the FSS will get the clearance for you and then forward it to you. On your initial call up tell them you are IFR to cabc. They will call centre, get the clearance, then read it to you. Read it back just like any other clearance and you are in business.

Okay, that's good to know. So even though they're not ATC, they'll be in contact with ATC and relaying clearances/instructions to me.

3. Venturing into class B will be seamless unless you are coming at it sideways, in which case the methods listed in 1 will work. Vertically you don't need to worry about it, if a handoff is required, you'll get it.

Hmm, how would you get it if it's Class G below? I guess it's the same thing as Example 1 then.

I haven't got my mittens off so I could be wrong, but I think this is question 4, not 2.

Depends how you count.

As for IFR in class G, it's the big sky theory, complemented with timely and good radio work. The frequency for this is 126.7 and the local airport frequencies when departing and arriving. Please not that when exiting controlled airspace into uncontrolled, you should make your 126.7 call before you get into uncontrolled airspace.

Wow, IFR flying in uncontrolled airspace is risky proposition, especially given that there are people who're there illegally, not talking and not listening.

VFR flight following is a value added service provided if you want it. If you are VFR in class E or G and do not want to talk to a controller, feel free. Personally I always take this service when available.

Yeah, I know that much, but how exactly do I know where exactly it's available? For example, when I was once flying west away from Toronto, the Toronto Terminal controllers did flight following for me for a while, and then said "radar service terminated" as I was a bit past Hamilton, giving me no further frequencies. Yet surely radar coverage doesn't end around Hamilton. So why wouldn't I be handed off to someone?

Don't worry about whether you are talking to centre, terminal, departure, or arrival. Would a rose by any other name ...?

I don't worry about it when flying, but when I'm studying and trying to make sense of things, it helps me if I can have the big picture of the ATC system, which right now is missing a few bits.

You should not be flying around VFR or IFR if you do not know what RCOs, DRCOs, FISEs, FICs and FSSs are and how to use them. Every private pilot should understand these thoroughly. Get a copy of the CFS and download the AIM and start reading.

I have read all of that stuff already. I know what AIM and CFS have to say about them, and I've used them (well, some of them, since I haven't yet been to an area that has a DRCO), but again, I wanted a bigger picture. For example, I found no very good explanation on the difference between FICs and FSSs. A few dry sentences in TC AIM and other TC publications don't give that much info about such matters, and don't explain nearly enough (no/few examples, no way of knowing how to use a lot of this stuff in real life until someone demonstrates it or explains in more detail), so I go on the web and look for other articles. For example, this article, seems to use FIC and FSS interchangeably. Yet they are not the same, I hope (if they are, why would they have two different names?)

The general trouble with TC AIM, CFS etc. is that a lot of the stuff is just way too vague. Another trouble is that it's often rather disjointed, scattered all over different regulations, so even if you read something, you never know whether you got a complete picture, or whether you're missing something that's in the regs somewhere. And some things are not even defined! For a somewhat unrelated example, there is no definition of what constitutes a cross-country flight, yet there are cross-country requirements for various ratings and licenses.

[chephy]

First of all, thank you for taking the time to share your knowledge.

You can get a clearance before you take off over the phone if necessary. Otherwise, you check for the nearest airport to you with a PAL and you call them prior to entering their airspace. They all connect to the area control center for your region and they will know what to do with you.

Ok, two answers now for "get in touch for somebody who's nearby and should know stuff". Fair enough, at least now I know that's the way things actually are (unclear at times), and it's not that I'm just missing something.

Example 2: You are wrong here. Class E is controlled airspace for IFR operations.

I know it is; I said as much. Yet it's still called an uncontrolled airport (see, the terminology is nuts!)

If you enter Class E airspace at an airport with an FSS, then you are still controlled and kept separated from other IFR traffic.

And who's responsible for keeping you separated from VFR traffic, if it's VMC out there? Are you supposed to practice see-and-avoid when flying IFR in VMC? I wouldn't want to depend on other VFR pilots to see and avoid me... (Sounds like a dumb question I should know the answer to... but I've just now hit the books to study the IFR stuff.)

Example 3: This depends on where you are and gets a little fuzzy. Up north, you can be as high as FL270 and not be in controlled airspace. In the south near major airports there will be the Class B above 12'500. Class B is not everywhere above 12'500 in Canada. Just near the major centers.

But the AIM says that "All low level controlled airspace above 12 500 feet ASL or at and above the MEA, whichever is higher, up to but not including 18 000 feet ASL will be Class B airspace." Surely MEA is not always above 12,500' outside major centres? ... At least I don't feel so bad about being so confused anymore.

As for your last question, ask yourself what is Class G airspace. ATC has neither the responsibility nor the authority to tell you what to do in Class G. You are on your own. This means you provide your own separation from other traffic even if you can't see it. How do you do that? 126.7, 123.2 and the MF or ATF frequencies of nearby airports will sort this out for you and your eyes as well when you pop out of the clouds. Just be aware that not every plane in uncontrolled airspace will have a radio and generally people with airplanes who live in areas of Class G airspace do some pretty strange things. I know of one fellow who didn't have a radio or any navigation instruments and he used to bomb around in clouds all the time to build his IFR time even though he didn't have an Instrument rating. Smart? No, but this shit happens more than you might believe.

Wow. See, there is nothing on this in TC AIM either... Though, of course, common sense does tell you that if there is a really stupid thing that can be done, there will be people who'll do it.

Last thing. "Center" is the frequency for a particular region that planes will be using, likely in cruise. "Terminal" is only used at major airports with the need for a Terminal frequency.They control inbound aircraft descending to the airport or control lower aircraft cruising through the area that aren't at an altitude that "Center" would be responsible for. For incoming traffic, Center would hand off to Terminal, Terminal would hand off to Tower. For outbound traffic, its the opposite.

Hope this helps

It does. Thanks again.

[AuxBatOn]

And who's responsible for keeping you separated from VFR traffic, if it's VMC out there? Are you supposed to practice see-and-avoid when flying IFR in VMC? I wouldn't want to depend on other VFR pilots to see and avoid me... (Sounds like a dumb question I should know the answer to... but I've just now hit the books to study the IFR stuff.)

Because you are flying "IFR" doesn't mean you can't look out the window when it's VMC out. On a training flight, sure you'll look inside most of the time, but your instructor is responsible for looking out. You are responsible for avoiding collision with VFR traffic in anything but Class B airspace.

ATC will only clear 1 IFR aircraft at the time in a classe E CZ. If it's a VFR day, you look out for VFR traffic. Period. Comms + good look out are essential.

[chephy]

ATC will only clear 1 IFR aircraft at the time in a classe E CZ. If it's a VFR day, you look out for VFR traffic. Period. Comms + good look out are essential.

Makes a lot of sense. I just wonder to what extent it's your responsibility. Of course, if you were right and dead, you're just as dead as if you were wrong, but for purely theoretical reasons (such as exam questions, if nothing else), are you responsible for avoiding VFR aircraft in controlled airspace?

[ahramin]

Wow, IFR flying in uncontrolled airspace is risky proposition, especially given that there are people who're there illegally, not talking and not listening.

I suppose this depends on your definition of risk. I have not heard of a single mid-air in IMC in uncontrolled airspace during my career, which suggests to me that this is low risk.

Yeah, I know that much, but how exactly do I know where exactly it's available? For example, when I was once flying west away from Toronto, the Toronto Terminal controllers did flight following for me for a while, and then said "radar service terminated" as I was a bit past Hamilton, giving me no further frequencies. Yet surely radar coverage doesn't end around Hamilton. So why wouldn't I be handed off to someone?

Is it possible the radar coverage does end there at your altitude? I have never flown VFR around there. In any case, you were leaving the area for which the controller could provide flight following. You could ask the controller for a frequency for further flight following, or you could try to figure it out for yourself. There is no comprehensive listing of where this service is available and on what frequency. I would start with the closest PAL.

Maybe there is a business opportunity here? Providing airspace charts for VFR pilots?

And yes, any time you are VMC, you should be looking out enough to spot all aircraft in your vicinity.

[chephy]

I suppose this depends on your definition of risk. I have not heard of a single mid-air in IMC in uncontrolled airspace during my career, which suggests to me that this is low risk.

You're right, the actual probability of such a collision is probably very small. I guess what bothers me is the same thing that bothers people who are afraid of flying commercially: even though they're far more likely to be killed or injured while driving to the airport, they feel in control while driving, but not when idly sitting inside a flying contraption. Similarly, when you're in clouds, you have zero chance of seeing other traffic, and you can only HOPE that they're following the proper procedures.

Having said this, the whole see-and-avoid VFR thing seems almost as flawed to me as well. When one looks at VFR minima for visibility, modern aircraft speed, and pilot reaction times, one can see that even if you keep a very thorough scan of the sky and notice other traffic as soon as theoretically possible, you don't have a lot of time to avoid a potential head-on collision. Combine this with the fact that most of the time you WON'T see other traffic that soon (sometimes you can't see them even if you're warned about them and KNOW where to look), and it gets... uncomfortable in congested airspaces. Add to that the inevitable blind spots, the notorious high-wing vs. low-wing issue, and you realize that there are many situations when you're just counting on that Sky to be very Big and/or on other aircraft having radios and using them on the right frequency (whatever that is....)

Is it possible the radar coverage does end there at your altitude?

It's possible; I wasn't very high. But I don't even know where to look it up (which areas have radar coverage to what altitudes), if there is a place to look it up.

In any case, you were leaving the area for which the controller could provide flight following. You could ask the controller for a frequency for further flight following, or you could try to figure it out for yourself. There is no comprehensive listing of where this service is available and on what frequency. I would start with the closest PAL.

This helps a bunch. Thanks.

[Hedley]

IFR flying in uncontrolled airspace is risky proposition

Not sure anyone cares about the facts, but if you run
the numbers, I am sure from an objective accident
per hour statistic, it is a far more risky proposition
to fly VFR in perfect wx at a busy uncontrolled airport
on a Saturday or Sunday.

And now back to your regularly-schedule swine flu hysteria ...

[ahramin]

The END is near.

[Pratt X 3]

For example, when I was once flying west away from Toronto, the Toronto Terminal controllers did flight following for me for a while, and then said "radar service terminated" as I was a bit past Hamilton, giving me no further frequencies. Yet surely radar coverage doesn't end around Hamilton. So why wouldn't I be handed off to someone?

My best guess, as I have had this happen before, would be that the Toronto Terminal airspace ended. They usually don't do the typical IFR handoff to Toronto Centre unless you specifically request it. VFR flight following is a non-priority service and is only provided workload permitting. In your example, when told "radar service terminated", requesting the Centre's frequency from Terminal would be the easiest way of continuing flight following. You would then need to call up Centre and request flight following from them.

[chephy]

My best guess, as I have had this happen before, would be that the Toronto Terminal airspace ended. They usually don't do the typical IFR handoff to Toronto Centre unless you specifically request it. VFR flight following is a non-priority service and is only provided workload permitting. In your example, when told "radar service terminated", requesting the Centre's frequency from Terminal would be the easiest way of continuing flight following. You would then need to call up Centre and request flight following from them.

Sounds reasonable; that's probably what happened. On a different occasion, when I was flying north instead of west, they did hand me over to Centre; maybe they weren't as busy then.

[randallg]

Wow, IFR flying in uncontrolled airspace is risky proposition, especially given that there are people who're there illegally, not talking and not listening.

I suppose this depends on your definition of risk. I have not heard of a single mid-air in IMC in uncontrolled airspace during my career, which suggests to me that this is low risk.

An interesting example is Masset BC, in the Queen Charlotte Islands, which I heard about in IFR ground school. It is a destination for rich fisherfolk going to the world class lodges in the area. It's uncontrolled but has non-precision approaches. In summertime bad weather there can be a number of bizjets from the US stacked up in hold, taking approach attempts one at a time, coordinating amongst themselves. Some crews from the US have little experience with busy uncontrolled operations like this. But it seems to work.

[FL001]

Ok, be very clear about what an uncontrolled airport is. Technically an airport with an operating FSS isn't "controlled" per se but there is a person on the ground with a responsibility to assist and watch over the aircraft in their area. You can do what you want at an airport with an FSS and its surrounding airspace provided you follow the CARS at all times and tell them whats going on. They will be watching. For me, uncontrolled means there is nothing but birds in the air and the deer watching you as they munch the grass on the runway.

As to the other point of "all low level controlled airspace" being Class B. Class B is only at the major airports and if I remember correctly, there was a chunk of airspace somewhere in Ontario that was Class B and not near any major airport. Someone from the area would know that better than I. Class B is not a huge deal. If you go to the US there is Class B airspace everywhere and again, above the major airports. The difference there is that they really try to keep all GA aircraft out. This means all the GA aircraft get squashed into as little as 3000 feet of altitude. I prefer the latitude that Canadian controllers give GA aircraft in Canada.

All the airways on LO charts will be Class E with the exceptions being close to major centers. With reference to the uncontrolled airport question, pull out a LO chart and look for the airports on it. Anything in the green areas is truly uncontrolled. You will notice that airports with an FSS are in the white areas. The airports and the airways are Class E. This means there is some form of control.

[kevenv]

As to the other point of "all low level controlled airspace" being Class B. Class B is only at the major airports and if I remember correctly, there was a chunk of airspace somewhere in Ontario that was Class B and not near any major airport. Someone from the area would know that better than I. Class B is not a huge deal.

Most airspace I work in the QM FIR is class B above 12500.

[chephy]

Ok, be very clear about what an uncontrolled airport is. Technically an airport with an operating FSS isn't "controlled" per se but there is a person on the ground with a responsibility to assist and watch over the aircraft in their area. You can do what you want at an airport with an FSS and its surrounding airspace provided you follow the CARS at all times and tell them whats going on. They will be watching. For me, uncontrolled means there is nothing but birds in the air and the deer watching you as they munch the grass on the runway.

Your interpretation makes sense, and it does indeed sound strange when someone talks about a control zone of an uncontrolled airport, but I have exams to write, so I try to stick with the "technical" definitions.

As to the other point of "all low level controlled airspace" being Class B. Class B is only at the major airports and if I remember correctly, there was a chunk of airspace somewhere in Ontario that was Class B and not near any major airport. Someone from the area would know that better than I. Class B is not a huge deal. If you go to the US there is Class B airspace everywhere and again, above the major airports. The difference there is that they really try to keep all GA aircraft out. This means all the GA aircraft get squashed into as little as 3000 feet of altitude. I prefer the latitude that Canadian controllers give GA aircraft in Canada.

Okay, I see where I was misinterpreting the AIM. So I guess that outside of major centres is just not "low-level controlled airspace", but Class G. Thanks for the clarification.

[kevenv]

Okay, I see where I was misinterpreting the AIM. So I guess that outside of major centres is just not "low-level controlled airspace", but Class G. Thanks for the clarification.

Wrong. You might want to seek clarification on all your points from an instructor in person rather than basing your studying for the tests on the answers you get here.

[chephy]

Wrong. You might want to seek clarification on all your points from an instructor in person rather than basing your studying for the tests on the answers you get here.

Okay, not just "outside major centres", but "outside of where it's Class B". Point is, it's not automatically Class B in Southern Domestic Airspace just because it's 12,500'+ .

Thank you for your concern, but there is nothing wrong with using the web and web forums as a studying tool, as long as it's not abused and answers are not taken on blind faith, but checked against appropriate references later. I do talk to my instructor and do read textbooks, TC publications etc. This kind of online conversation accounts for no more than 0.5% of my overall sources; yet it can be quite useful when the textbook is too dry and terse to be of use, and the instructor is unavailable and/or not sure about something himself (I have never met an instructor who knows everything about flying, and I don't think that's humanely possible).

[Spokes]

All the airways on LO charts will be Class E with the exceptions being close to major centers. With reference to the uncontrolled airport question, pull out a LO chart and look for the airports on it. Anything in the green areas is truly uncontrolled. You will notice that airports with an FSS are in the white areas. The airports and the airways are Class E. This means there is some form of control.

I could be wrong (and often am), but it was my understanding that Low level airways turn into class B above 12500, or MEA if it is above that (to below 18000 of course). Have I gotten that one wrong?

[FL001]

Yes you are right. I guess I have to define what "near a major center" means. Airways above 12,500 up to 18,000 are Class B or the MEA and above. Up north and in mountainous areas though, the MEA can easily be 18,000 feet though. Here is a good website that describes your Class B problem. Better yet, spend an hour with an instructor and they should be able to hammer out all your questions in person. That has to be way more efficient than this. Short of writing out the whole AIM to explain your issues.

http://bathursted.ccnb.nb.ca/vatcan/fir ... Topic.html

[BTD]

RAC 2.8.2
All low level controlled airspace above 12 500 feet ASL or at and above the MEA, whichever is higher, up to but not including 18 000 feet ASL will be Class B airspace.

Control zones and associated terminal control areas may also be classified as Class B airspace.

Examples of Low level Airspace are:

Low level airways
Control Area Extensions
Control Zones
Transition Areas
Terminal Control Areas

If it is uncontrolled Class G below 12,500 there most likely isn't any class B above. Class E is considered controlled airspace.

BTD

[kevenv]

If it is uncontrolled Class G below 12,500 there most likely isn't any class B above. Class E is considered controlled airspace.

North part of YQM FIR (Bathurst area and even into Montreals airspace) is uncontrolled below 12500 and class B above...

[BTD]

That's why I said most likely. Never talk yourself into a corner.

However, more often then not if it is class G low level airspace there won't be class B above. If you're unsure, either look at the charts or try to raise the centre on the PAL prior to going above 12.5.

BTD

[sakism]

So there is no publication that lists all of that stuff for you and no sure way to know this without talking to someone, in other words? Aww, too bad.

Each LO/HI chart has all the Centre frequencies in use for the chart area listed on the legend page, along with the site where the frequency is located (or relayed through). They are also located in the CFS under the city where the ACC is located (ie. Edmonton, Winnipeg, Toronto, etc.)

Pick the closest one - as someone else said they'll tel you if you're on the wrong frequency. After a couple of times you'll get to know the areas covered by each frequency.