Bill’s Nova Scotia Radio Site

Aeronautical Control Sectors and Frequency Usage in the Moncton Control Area

(with an explanation of simulcasting and cross-coupling)

Last updated
October 30, 2017

This is the fourth in a series of pages intended for scanner listeners who are interested in listening to aircraft arriving and departing Halifax.  It is tailored to those scanner listeners who also might want to go to the airport and combine listening with watching.   You might find it useful to start with Part 1:  At the Airport and follow the sequence.


1. The Airport   2. Flight Plan, Taxi and Takeoff  3. Departing the Airport Vicinity  4. Moncton Centre and Surrounding Zones (High and Low)    5. Arriving at Halifax, Landing, and Taxi to the Gate

I am not a pilot or air traffic controller but have listened carefully for many years  If you are already well-versed in this subject you may find parts that you find very elementary in nature, or even misleading.  If so I welcome any suggestions for improvement.    This page should be read in conjunction with my pages on Low-Level and High-Level Flight Activity, and will also be vital when you use on-line aircraft tracking sites.  Due to my location I am writing particularly about my local situation but most of what is said ought to apply in principle to your own area.

(This is a simplified description)

Controlled airspace exists all over the populated parts of North America including an off-shore fringe that is within radar and radio coverage of ground-based stations.    While the structure of this controlled airspace can be quite complicated, the basic concept is that there are four kinds of controlled space.   I am not intending to describe in official terms the various types, which, depending on the jurisdiction may include more than four types.

Airport Control Zones (Controlled by "Tower")

Busy airports will have a control tower that directs aircraft to take off and land, and to maneuvre in the local area.  Typically this Control Zone is a circle that is from ten to thirty nautical miles in radius.    The CZ only extends upwards a short distance, so that the airspace above that limit does not belong to the airport control facility.    While the surface traffic is also controlled, by a ground controller, the airport control zone activities will be on the Tower frequency.  In some large airports there are separate tower frequencies for different runways.   This is not the case at any Maritimes airport.   In fact there are only a few airports in the Maritimes that have a control tower, these being Halifax, Greenwood and Moncton (full-time) and Fredericton (part of day) and as well Shearwater with more sporadic service.   In the past there were control towers at Saint John, Yarmouth, Charlottetown and Sydney but cost-cutting years ago eliminated them, other than the structures themselves. 

On the radio the call sign for the tower is of course "Anywhere Tower" but keep in mind that in a few situations outside the Maritimes the name may not be what you might expect.

An aircraft approaching a tower airport will be on the tower frequency (= under control of the tower) for perhaps the last 10 miles or so of the approach.  On the other hand, when an aircraft takes off, it is immediately handed over to Terminal unless it is doing circuits immediately close in.

Note that airports without towers are uncontrolled which in essence means that the pilots are on their own as far as taking off and landing are concerned, but on the other hand many of the busier uncontrolled airports have communicators who can advise on weather and runway conditions.  In Sydney, Saint John, Charlottetown this is a Nav Canada radio facility.  In others such as Debert it is a private Unicom.   Where there is no communicator assistance the pilot merely announces intentions and visually checks the field prior to landing.

Terminal Control Areas (Controlled by "Terminal", AKA "Arrival" or "Departure")

The next category is the Terminal Control area that surrounds major airports.   This is generally a circular area out to perhaps 50 nautical miles, and like the airport control zone only extends to a certain altitude above the ground, on the order of 5000 feet.     The area is controlled by ATC personnel in a TCU or Terminal Control Unit.  All aircraft intending to land at the particular airport will come under the direction of the TCU, as do those that have just taken off to depart the airport area.    In the Maritimes only Halifax and Greenwood have TCU’s.   The military TCU for Greenwood is thought to operate 24/7 whereas the Halifax TCU shuts down during the quiet overnight hours and the terminal area becomes part of Moncton Centre’s airspace, as described next. In fact, the Halifax TCU is co-located with Moncton Centre in Riverview (see next item)..  [Note.... it is possible that Moncton also has a part-time TCU.  If you know for sure one way or the other, please let me know.   email me   marscan1 AT]

On the air the call sign for Terminal Control Units can be "Anywhere Terminal" but it can also be more specific depending on the situation.  An arriving aircraft might use the the call sign "Anywhere Arrival", or in the USA "Anywhere Approach", and if departing might say "Anywhere Departure".  Around some very busy airports the arrivals and departures could be on different frequencies, but in most cases they just use one for both arrivals and departures and you might hear both call signs on one frequency.

 Air Route Control (Controlled by "Centre")

The top category of control is the Area Control Centre, for this area located at Riverview, New Brunswick and called “Moncton Centre”.  ACC’s control aircraft on flight routes heading through a region or en route to, or departing from, a terminal area or airport that does not have a TCU. In this region there are two levels of area control.  In some areas outside the Maritimes there will be more than two levels.

LOW LEVEL:  In our region low level extends from the ground or upper level of terminal or tower areas up to approximately 28,000 feet.  For the most part Low Level is where you find smaller aircraft enroute transitting the zone or travelling between airports in our zone.  Mostly you will hear larger aircraft that are either descending from high level on their way down to land, or vice versa.  Occasionally you will hear long range flights within it, but usually only for a particular reason that precludes high level flight at that time. For example, on October 29, 2017 a very large number of inbound trans-Atlantic flights were passing SW down the spine of Nova Scotia and were encountering turbulence at their normal high levels and therefore many opted to fly at 25000 to 28000 feet, and therefore were on the Low Level frequencies.   Outside of these unusual circumstances it is common to hear turboprop airliners for example will fly low level, even if on relatively long flights such as from Ontario or New York to and from Halifax.

HIGH LEVEL: High level is Flight Level 29 and up and is populated by aircraft passing over en route to and from Europe, plus aircraft within the region that are en route to area airports but have not yet descended into low level airspace, or vice versa.     Note that in the United States the term for these units is Air Route Traffic Control Center or ARTCC.  The Boston Center area immediately adjoins on the west Moncton Centre’s area.  Note the difference in spelling between the two countries.   These centres are sometimes referred to by their international codes, such as ZQM or CZQM for Moncton, and ZBW or KZBW for Boston.

Each of the two levels is itself divided horizontally into sectors.  Sectors are predetermined geographcal areas that in theory could each have their own controller on a separate frequency.  In practice various combinations of adjoining sectors will be joined together under one controller and frequency, but this is a dynamic situation in which the combinations can easily be changed to meet current needs. 

LEVELS AND SECTORS:    Air Control Zones such as Moncton, Boston and Montreal are divided into low and high levels.   The dividing altitude varies from zone to zone but is generally around Flight Level 28 (more or less equivalent to 28000 feet ASL).   In addition both the low and high levels are divided horizontally into sectors.    Generally speaking each sector has at least one distinct frequency to serve it.  In busy hours it is possible that each sector and frequency is operated by a separate air traffic controller but it would be more common for two or three zones to be operated by one controller. 

At night in quiet hours, it is common for several or many sectors to be consolidated under one or two controllers.   In consolidation there are two levels of frequency amalgamation:

In simulcasting, the controller listens to several zone frequencies but when replying keys all of the frequencies.  This means that what goes out on one ground transmitter also goes out on the others.  The intended target for the comments is listening on its particular frequency but the voice of the controller goes out on all the selected frequencies, thus doing away with any need for the controller to individually select which frequency to transmit on. If for example you are in range of the ground transmitter at Halifax, as I am, in the night you can hear the controller talking to aircraft all over the Maritimes.  You will still only be able to hear the aircraft side of the conversation on the frequency that aircraft is transmitting on, if in fact you are close enough for reception.  

In cross-coupling each of the separate frequencies is re-transmitted on all of the other joined frequencies.  Not only does the controllers' voice go out over all of the joined frequencies as in simulcasting, so do all the transmissions from the aircraft.   This means for a scanner listener that if they tune in a local frequency and can hear the ground transmitter, they will hear all of the communications throughout the joined area.   This only works for scanner listeners if they are in range of a ground station.   For example I am in range of the Moncton low level transmitter on 135.3 MHz.  If it is cross-coupled with the frequencies in adjoining sector(s) I can hear it all, both the aircraft and the controller.   The extent of cross-coupling varies but certainly at times ALL of the low sectors in the Moncton zone are connected.  In the high level it is common in quiet hours for the eastern half of the Moncton zone to be cross-coupled, and presumably the western half will be separately cross-coupled.


LOW LEVEL SECTORS in the Moncton Zone (and surrounding areas)

This is mostly for the local traffic within the region, and aircraft coming out of the high levels to land at an airport or vice versa.  Occasionally there will be transiting aircraft that are merely flying over, but are doing so in the low category of altitudes.

Due to Halifax having by far the most traffic landing and departing (other than the small aircraft training centres), several of the low level sectors more or less radiate out from that airport as can be seen in the chart below.  For radio listeners it is perhaps better to think of the frequencies used rather than worrying too much about the sector boundaries. Thus there is an area extending from the Halifax area southwest towards Yarmouth and the mouth of the Bay of Fundy and using 123.9 MHz. There is another in the opposite direction on the mainland, towards Cape Breton using 135.3, and another beyond that on 118.6, serving the Cape Breton area and beyond over the Cabot Strait to the boundary with Gander Centre.  

The Moncton low level diagram shown below clearly shows this pattern as well as all the other Moncton Low sectors and those of the adjoining centres.  This diagram is produced from information gathered from various official documents as well as observation by myself and other enthusiasts.  This chart does not show the military terminal area surrounding CFB Greenwood.

The following is my own map that is intended to show at a glance the frequencies in use but does not show the sector boundaries.

All communications between Area Centres and aircraft are via remotely controlled transmitter/receivers located in some cases very far from the location of the controllers at the centre. These remote sites are referred to as PAL's (peripheral sites) in Canada and as RCAG's (remote controlled air/ground sites) in the USA.  For the frequencies shown above the actual sites are as follows:

Boston 133.45 Bucks Harbor (also used high level)
Boston 124.25 St. Albans
Boston 120.25 Houlton
Boston 124.75 Caribou
Montreal 125.1 Riviere du Loup
Montreal 134.65 Mont-Joli
Montreal 134.175 Gaspe
Montreal 135.55 Sept-Iles
Moncton 123.9 Wellington (Yarmouth) West group in simulcasting and cross-coupling
Moncton 124.3 Clarendon  West group in simulcasting and cross-coupling
Moncton 135.5 Clarendon  West group in simulcasting and cross-coupling
Moncton 132.2 Riverview (Moncton) West group in simulcasting and cross-coupling
Moncton 132.5 Caledonia Mtn  West group in simulcasting and cross-coupling
Moncton 134.25 Dalhousie  West group in simulcasting and cross-coupling
Moncton 123.7 Miramichi  West group in simulcasting and cross-coupling
Moncton 124.4 Riverview (Moncton) East group in simulcasting and cross-coupling
Moncton 134.35 Iles de la Madeleine  East group in simulcasting and cross-coupling
Moncton 135.65 Charlottetown  East group in simulcasting and cross-coupling
Moncton 135.3 Halifax East group in simulcasting and cross-coupling
Moncton 118.6 Sydney East group in simulcasting and cross-coupling
Moncton 119.2 Halifax (when Terminal not in operation) East group in simulcasting and cross-coupling
Gander 132.3 Stephenville
Gander 134.9 Allan's Island

Note that "terminal" communications are via transmitter/receivers located near the airport served by the terminal unit.



HIGH LEVEL SECTORS in the Moncton Zone (and surrounding areas)

The high level sectors in Atlantic Canada are arranged to match the predominant NE/SW traffic patterns.  While there are many flights each day cutting across this pattern, coming in and out of our airports, most of the traffic is travelling in a southwest to northeast direction, from places like New York and Washington to Europe and beyond, or vice versa.   There are many more or less parallel tracks, and which one or ones is used on any particular day and time depends principally on the wind conditions, which more or less means the position of the jet stream.

The first diagram below showing high level sectors for Moncton Centre clearly depicts the parallel nature of the sectors in our region.  Note that the diagram is tilted so that north is towards the top right.  This diagram is from several years ago and therefore there are a few frequency changes and many changes in reporting points since then, and perhaps even modification of sectors.  Unfortunately I do not recall where I obtained this chart, and therefore cannot acknowledge that source here.   This chart may be hard to interpret without knowing the codes for the airports that are shown. 

TU/QY (TUSKY/Sydney) is the pair of sectors aligned along the spine of Nova Scotia, and contains at least one flight track.  The next one down is BR/FO (BRADD/FORTE), and the next is KN/GY (KANNI/GRAYY), and so on.  You can see that other sectors join on to the southwest and northeast in the Boston and Gander areas respectively.  These sequences of sectors lead on to oceanic entry points just east of Newfoundland.

The upper parts of this sector chart are for areas well up into northeast Quebec and Labrador.   Surrounding centres’ sectors are shown with colour or shading, light green for Montreal, shading on the west for Boston, and shading on the east for Gander.  While each zone has a designation, you will never or hardly ever hear them mentioned on the air, and therefore you could disregard them.   They might conceivably have significance if you come across a frequency list that shows frequencies by sector.   Sectors are named after either a town within the area, or a reporting point.  For example QY is the Sydney sector, named after the aero code for Sydney, and WH is the Whale sector, named after a reporting point of that name offshore west of Nova Scotia.


The following chart may be of more interest to you as a listener as it more simply shows the frequencies used in particular areas.  The individual sector boundaries are not shown as they have little actual relevance to this monitoring activity.   Instead it shows the boundaries between the various ACC’s for high level control, and indicates the general area covered by various frequencies.    Depending on the actual tracks being used, the frequency coverage is moved as needed.  For example if most of the traffic is relatively far offshore of Northeast Nova Scotia, 125.25 will be used for it, but  133.3 and 133.7 which are normally lightly used, will be inserted for use closer to the coast.   Otherwise it would be common for 125.25 to be used for all the traffic in this general area.

Note that the areas farther into the ocean and designated “oceanic” are considered to be out of range of VHF radio and/or radar coverage and therefore beyond the control of Area Control Centres. The oceanic areas come under the jurisdiction of the long range oceanic centres  (New York and Gander in this part of the world).   Due to there being no radar coverage, once an aircraft is in an oceanic zone they must provide position reports periodically to the appropriate oceanic controller.   Voice radio communications, if used, will be on HF frequencies not listenable on a scanner.  You will commonly hear eastbound aircraft being given their oceanic clearances, i.e. their routings to Europe, prior to leaving the VHF coverage area.  These voice, on the air, clearances might be done by the Moncton controller, or might be done directly by Gander Oceanic on one of their clearance delivery radio sites.  In the Maritimes there is a site at Sydney on 119.425 MHz.  Clearance delivery might also be done by datalink (ACARS) which is something you can also monitor if you have the necessary equipment.. I myself have not yet gone into this part of the hobby. 

At the risk of stating the obvious, the ground transmitters for the frequencies shown above in the charts as being out at sea are of course not in the ocean.   While some centre transmitters are located in the vicinity of the actual centre, most are remote and fed via landlines or perhaps microwave links.  These remoted facilities are referred to as PAL’s, coming from the word “peripheral”. In the United States they are referred to as RCAG’s (remote controlled air-ground) facilities.  My chart below outlines the various high level frequencies in our region, arranged by centre and transmitter location.   When I say transmitter I should say that there will always be an associated receiver as well but it will likely be a few kilometres away from the transmitter.

There are several locations for these PAL’s and in some cases the service area is far from the transmitter location.  Perhaps the most extreme example is the transmitter at Halifax on 133.95 MHz.  This is for occasional use by aircraft passing far offshore and perhaps at the extremes of coverage from Yarmouth and Sydney ground stations.  It is actually relatively uncommon to hear any aircraft on this frequency due to the relatively remote service area, meaning it is not used frequently, and if it is the aircraft are far out to sea.  The chart below does include the ground station location for most of the frequencies. 

Having said that you will hear few aircraft actually on 133.95 you will hear a fair bit of traffic on that frequency if you are in the Halifax area.  At times you will hear the whole eastern area of the Moncton zone.  This apparent contradiction is due to cross-coupling as described farther up this page.   In this case the transmissions of aircraft on all of the coupled frequencies are being re-transmitted over the ground transmitter at Halifax.  So if you are hearing an aircraft up in the southern fringes of Labrador on 133.95, you are NOT hearing it direct.  Its transmission has been picked up by a receiver in that region and sent by surface lines to Moncton Centre, then sent back out to the Halifax transmitter and retransmitted.    This will also be the situation with your own local area ground transmitter.   So I can sit on 133.95 in the quiet hours and hear what is going everywhere in the eastern part of Moncton's zone.  In busier hours I must scan as normal to hear aircraft in various sectors, and will likely not be able to hear traffic coming from far away parts of the Moncton zone. 

There are other frequencies used by high flying aircraft for purposes other than communicating with area control centres. AIRINC oceanic transceivers on 129.9 are located in several locations and similar Nav Canada 126.9 a/g frequencies are also heard.   Listeners should also monitor 123.45 air to air, and 121.5 VHF guard frequencies.

Aircraft being given crossing clearances from Moncton Centre are often cleared via the outer row of reporting points ranging from TALGO (just above the "New York Oceanic" title) and those along the Gander Domestic/Oceanic boundary.

HANDOFFS:   Aircraft are handed off from one sector to another within a particular ARCC zone, or between ARCC's.   While you might expect that the hand-off would be done as the aircraft crosses the boundary, this is not usually the case.   The most obvious example is the handoff from Moncton to Boston and vice versa.   Aircraft are usually still well within New Brunswick airspace when handed to Boston, and similarly when eastbound will be still in Maine when passed to Moncton.   Another common example is the handoff from Gander to Moncton when an aircraft is still well east of the boundary between these zones.  Because of this ahead of time handoff, I like to think of all the sector boundaries as being more like fuzzy ribbons rather than precise lines.


While the frequencies used in this area are shown on the various charts above, you may find it useful to refer to this straight-forward list.  A similar list might be produced in the future for low level frequencies.

As receivable on-air from the Halifax, Nova Scotia area or via cross-coupling.

 ATC communications between area control centres and aircraft are predominantly via remotely operated ground stations or sites that are located in some cases very far from the community in which the controllers are situated.  These remote stations are referred to in Canada as PAL's and in the USA as RCAG's but as in other fields, the American terminology is sometimes used here as well.  The range of these ground stations is 200 miles or more for high-flying aircraft, but on the ground their signals might carry only 30 miles or so at the best. Therefore, on the radio and situated near Halifax you will not hear the ground stations directly, other than the one near Halifax airport on 133.95, but you certainly can hear the aircraft side of communications through all the other sites listed unless specifically noted.  For example I regularly hear aircraft over the Gulf of Maine speaking to Boston Ctr on 133.45 via the Bucks Harbor RCAG but I cannot even hope to ever hear the replies being transmitted by that station.

The Maritimes area is served by Moncton Centre, located in Riverview, New Brunswick; however there are other centres serving adjacent areas, these being Boston Center, Montreal Centre and Gander Centre.   This chart is based on reception in the Halifax area, and from there you should be easily able to hear aircraft in contact with Boston Center but not normally the others, due to distance.

You will not hear the ground side of the communications unless you are located within a few kilometres of the ground transmitter.    The controllers on these frequencies are located at one of the "centres" serving the region, either Boston ARTCC (Boston Center) located in southern New Hampshire, Moncton Centre (located in Riverview across the river from Moncton itself) or Gander Centre in Gander, Nfld.   Most communications are however via PAL's or peripheral transceivers located at great distances from these control centres.   Generally these remote sites are connected to the central site by land-lines.   Regardless of the location of the PAL, the call sign used is the name of the centre controlling that facility.

Depending on the altitude of the aircraft, you will be able to hear its side of the communications up to about 300 km away but this is a very rough guide and subject more to your antenna and receiver than to your location, unless you are in a deep valley.


Boston Center (KZBW)

Only the airside will be heard from the Halifax area.

The ground side of these frequencies as well as enhancement of the airside may be monitored on-line via


Boston ARTCC (“Boston Center”) transceiver at Bucks Hbr, Maine and serving the Gulf of Maine from the boundary with Moncton.


Boston Center transceiver at Augusta, and serving aircraft in central and eastern Maine that are transiting SW to NE and vice versa.


Boston Center facilities at Millinocket and Houlton, and serving the northern part of Maine, and principally catering to aircraft transiting between Ontario/Quebec and Atlantic Canada

Moncton Centre (CZQM) West Area
Only the airside will be heard from the Halifax area.  If you live near one of the ground sites you will hear both sides of that frequency, and all of them if the sites are coupled.

128.375, 132.975, 135.2


Yarmouth PAL for Moncton Centre.   135.2 is in steady use and serves aircraft passing along the spine of Nova Scotia up as far as approximately Sheet Harbour.   The other frequencies are in less steady use and apparently are only in use when there is heavy traffic offshore, in which case one or both will be put into use. 128.375 appears to be the #3 frequency used only for far offshore traffic.


Moncton Centre.  The facility is not a PAL as it is located near Moncton.  It serves the western part of New Brunswick and along the Bay of Fundy.


Moncton Centre.  Not a PAL.  It serves eastern New Brunswick and east to the boundary with the Grindstone 132.8 frequency.


Sept Iles PAL for Moncton Ctr.  This frequency serves the northeast part of New Brunswick and north past Gaspe to the north shore of the St. Lawrence.  Occasionally you might hear aircraft on this frequency from the Halifax area, but if not, you will hear it mentioned quite often.

Moncton Centre (CZQM) East Area

133.95 Unlike all the other sites listed here, this is the only one that can be heard in the Halifax area as the ground range of these sites is only approximately 30 - 40 km at best.

Halifax PAL  This facility is intended to serve the far offshore adjacent to the middle part of Nova Scotia. It is in rare circumstances used by NE bound aircraft.  This site may not have much direct traffic but it is always simulcast with 125.25 so you will commonly hear the controller speaking to aircraft on that frequency through this site. It is often also simulcast with many of the other East Area sites. If you keep your radio on scan you may hear the other side of the conversations.  When cross-coupling is in effect you will have rich rewards on this frequency, which is also the case for listeners near other ground sites listed here.


Sydney PAL, serving the northeast end of the spine of Nova Scotia and in constant use.


Sydney PAL, serving the offshore of eastern Nova Scotia and is in very frequent use. 


Sydney PAL used in busy periods or on occasion to replace 132.75.  When used as an additional frequency it appears to be geographically variable, used either offshore to the southeast or to the north.


Sydney PAL, used in busy periods for traffic offshore of NE Nova Scotia, and generally inserted between 132.75 and 125.25.  


Grindstone, Iles de la Madeleine PAL, serving the central and eastern Gulf of St. Lawrence. 

133.55, 120.325

Stephenville PAL, serving the western Newfoundland area.   I do not think I have actually heard 120.325 being used.  Aircraft using the Stephenville PAL are usually not directly able to be heard in Halifax.


Natashquan PAL serving southeast Quebec and western Labrador.  Aircraft using this frequency are not heard directly in Halifax due to distance.

Gander Centre (CZQX)

134.7, 132.05, 128.175, 125.075

Trepassey PAL for Gander Centre.  If you live in central or western Nova Scotia you will not likely hear aircraft on these frequencies due to distance, but you will hear aircraft heading northeast being handed off to them.  These are the frequencies used by aircraft passing along, and offshore from, the south and southeast coasts of Newfoundland. 134.7 is the most common.

Gander Oceanic (Gander Radio)

135.05, 128.45, 119.425

These are special purpose PALS belonging to Gander Oceanic and are located in Allan's Island, NF (south tip of Marystown Peninsula) and Sydney NS.   These frequencies are used exclusively for passing oceanic clearances to aircraft proceeding eastwards across the Atlantic.   Clearances are occasionally also passed over regular frequencies.


Note also that most aircraft pass from Boston Center's control to Moncton's and then to Gander's or vice versa.   A few leaving Halifax will head more easterly towards southern Europe or south over the Atlantic on their way to the Caribbean and in those cases they will leave Moncton Centre and VHF radio behind and move to HF Oceanic frequencies in communication with New York Radio.  These frequencies are not receivable on a scanner and you will require a communications receiver capable of receiving 3 to 30 MHz SSB.