Bill's Radio Site
formerly the THE MARITIMES SCANNING SITE
(and Observing) High Level Air Traffic
Passing Over Nova Scotia
Last updated June 16, 2015
THIS PAGE REQUIRES IMMEDIATE UPDATING. AT PRESENT IT OVERLAPS WITH NEWER MATERIAL IN THE AIR CONTROL SECTORS PAGE
Singapore Airlines Airbus A380-800 9V-SKK
June 15th 2012 flying at 38,000 feet over Yarmouth, taken by Howard Doucet (Canon T1i with Sigma 150mm-500mm Lens, F18 @ 1/200sec)
This page is intended for the hobbyist who is interested both in radio and in aircraft, and discusses the high-flying traffic passing over or nearby to Nova Scotia. I have a separate page that covers listening to and observing aircraft flying lower and mostly arriving and departing from our airports, and if you like to look up at aircraft on approach for landing, or even go out to the airport to watch and listen, that is the page for you. There is a connection of course between these two pages, as some of the high-fliers transition to and from the low levels as they are not simply passing by, but rather coming to, or departing the Maritimes. I also have another page regarding a specialty topic, that being the Air to Air Refuelling carried out by the US Air Force over this province.
Nova Scotia has a multitude of aircraft passing by or over it every day on their way between Europe and the Eastern Seaboard of the US and other parts of the Americas. There are also aircraft actually arriving at, or departing from our own airports. While most of the air traffic is scheduled passenger and cargo airliners, some is general aviation and some is military in nature. It is easy to listen to these aircraft, observe most of them on-line, and even, as the photo above testifies, photograph them as well! Other than a few clumsy attempts to take pictures myself, I restrict myself to listening and to following aircraft on-line. Another aspect that I am not involved in is to receive transponder data directly, and while I would like to be doing that, I will not be for the present commenting on that aspect of the hobby. To most people, what I do cover here will be far from exciting. I am a little unusual in that when I see a contrail far above me I wonder what kind of plane it is, and where is it coming from and going to. Listening to the scanner has for many years given me clues as to which aircraft it is, but more recent advances in online mapping has in most cases made identification a snap. To add to my "unusualness" I actually listen to aircraft while I drive. My BCT-15 in the car is programmed for the aero bands and little else, and even after many years I find it fascinating to hear something like Speedbird 23 calling in to Boston Centre from somewhere over the Gulf of Maine, while I am driving around the Halifax area.
This page is necessarily centered on my own location near Halifax, but most of what I describe and detail will be applicable elsewhere in the Maritimes, with the major difference is that if you are in the far northeast, northwest or southwest of me, you will be hearing additional frequencies farther away in your direction, and perhaps less from the opposite end.
WHAT YOU CAN OBSERVE
The first comment to make may already be well known. The air routes from the US East coast to and from Europe are extremely busy with passenger and cargo airline traffic, with corporate aviation, and with military flights. Practically everything transitting these routes passes over the Maritimes. Depending on the jetstream location at the time, the preferred and therefore busiest route might at one time be over New Brunswick, another time along the spine of Nova Scotia, another time just off-shore, and other times farther out to sea. Note that due to the optimum timing for flights to arrive and depart on both sides of the ocean, there are periods of the day when most of the traffic is westbound, and others when it is eastbound, and some when there is very little traffic at all. There is never an absence of flights, as cargo aircraft in particular fly at odd times and/or the opposite direction, as do a few passenger aircraft, corporate and military flights. This screenshot from planefinder depicts a medium density situation whereby most traffic is westbound and is passing over New Brunswick and the Gaspe area. For me the maximum interest is when traffic is more so over or just offshore from Nova Scotia, which much the more common scenario, with the skies full right up past St. John's.
Most aircraft crossing the Atlantic to and from cities ranging from Washington to Boston will stay close enough to land as much as possible so that while they may be offshore they remain in radar and VHF range all along the coast from Newfoundland to wherever they are coming from or going to in North America. In the screenshot above, the single aircraft farthest south from Nova Scotia is just going out of the extreme range of radar and VHF from the Yarmouth area, and is entering oceanic areas without such coverage. The aircraft to the northeast, near Sable Island, remains in range of Sydney facilities. Many aircraft from farther south, such as Miami will do the same, and you will find also many from Mexico and the southern interior of the US will also pass nearby to the Maritimes. Flights to and from Chicago, Toronto and Montreal also will be very common. On the other hand you will not see many to and from the far west as it is shorter for them to pass over northeast Canada, and similarly, traffic to and from South America may tend to fly across a more southerly route. In relation to the European destinations and origins, most of the traffic oer the Maritimes is to or from Northern and Western Europe, with some also to the Middle East and Southern Europe, but some long-haul flights to these latter areas will be transit to the south of the Maritimes. While not covered here on this page, note that aircraft that are out of range of radar and VHF will be using satellite communications, or still most commonly, HF communications on SSB, for which you will need a communications receiver.
1. ON THE RADIO
The central focus of this page is listening to high flying aircraft on the scanner. The chart below was current in 2012 and little has changed since then. Keep in mind that there are other aero frequencies used by aircraft flying in lower airspace and yet others used in and around airports in the region. While the frequencies shown are in the 118-137 MHz aero band, there are also some communications, by military aircraft, in the 225-400 MHz band, and as well, in the farther offshore, HF communications in non-scanner frequencies ranging from 2 to 27 MHz. This page does not cover these latter bands, but the UHF band is referenced in the Air to Air Refueling page mentioned above.
What will you hear? Before you get too excited about this, you must realize that you are going to hear very little actual conversation. For the most part you will hear aircraft checking in as they change from one control sector to another, and occasionally asking for an altitude change or perhaps a deviation due to weather, or the controller might initiate a change due to potential traffic conflicts. In rare circumstances you might be listening when a pilot comes on to report a problem that will require immediate action, maybe even an emergency, but in relation to the large number of flights passing by this is certainly well out of the ordinary. And you must understand from the outset that generally you are only going to hear the aircraft side of the communications. For example if you live in or near Halifax and an aircraft transmits on 135.2 you will likely hear it whether it is nearly overhead or all the way down over the Gulf of Maine, but you will not hear the ground side of the conversation as that is being transmitted from Yarmouth, and this is much too far away from Halifax to ever be heard. If however you live nearby to one of the ground transmitters you are in luck, as you will hear both sides of the conversation on that particular frequency. For me, near Halifax, I can hear both the ground side and air side of 133.95 MHz as the ground transmitter is located near Halifax airport.
In looking at this chart one must first realize that aircraft flying over our region at high levels are under control of ATC personnel at area control centers. The centre for the Maritimes and for much of northeast Quebec and into Labrador is Moncton Centre, located at Riverview, New Brunswick. Adjacent to Moncton's zone are Gander Centre, Montreal Centre and Boston Center (located at Nashua, NH). Note the difference in spelling between Canadian and US agencies. From Halifax it will be normal to hear aircraft talking with Moncton and Boston, but the others are a bit too far away, though some reception is possible. Each of these zones is divided into sectors that have different working frequencies. Due to the fact that the amount of traffic varies greatly during the course of a day, and the fact that the routings of aircraft vary greatly from day to day, the usage of the sectors and the frequencies vary as well. For example, in a quiet period, several sectors may be combined under one controller and just one or two frequencies actually used. In a day when the wind pattern causes aircraft to fly farther offshore you will find that the frequencies will also shift their geographical usage. For example, in such a day, the 125.25 frequency shown off the coast of Nova Scotia will serve farther off-shore, and 133.7 might then either be put into service or moved, to serve the closer in-shore traffic. The map therefore is somewhat flexible but more or less correct regarding the area of use for each frequency. It must be stated now that despite Moncton Centre being located near Moncton, its transmitters and receivers are not all located there. In fact most are not. Most frequencies are remotely operated from Moncton and are referred to as PAL's or peripheral stations. For example, the frequencies shown in the southwest area of Nova Scotia have base transmitters and receivers located near Yarmouth, whereas those in or near northeast N.S. are located near Sydney. 133.95 is located near Halifax. A similar situation applies to the other centres.
HIGH LEVEL ATC FREQUENCIES and CONTROL BOUNDARIES IN THE MARITIMES AND SURROUNDING AREA
This map shows the boundaries of the several control areas in this region. Note that the far offshore or "Oceanic" areas use HF radio for communication and are not actually under control of ground personnel. Boundaries are in some areas approximate in the sense that boundaries do vary in some areas depending on the altitude of aircraft. The boundaries as shown are useful when monitoring high flying aircraft. For some altitudes Moncton's area continues north into Eastern Quebec and Labrador, but for some other altitudes this is Montreal's territory. The 126.325 frequency shown is a Moncton frequency. The locations chosen for the frequency captions are intended to give a basic concept of what areas are covered by what frequency, however the actual transmitters are of course on land. For example the 133.95 transmitter and receiver are near Halifax Airport, and 133.45 for Boston is at Bucksport, off the edge of this map. See the chart below for dedicated oceanic clearance frequencies. 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.
MAIN FREQUENCIES AT A GLANCE (May be useful to use the map above together with this list)
For those of you who wish to simply program
frequencies and not bother with explanations, here are the main high level civil
ATC frequencies generally listenable from central Nova Scotia.
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.
133.45, 134.95, 128.05
|Boston ARTCC ("Boston Center"). Aircraft on these frequencies can regularly heard from the Halifax area. These frequencies are for the Gulf of Maine (Bucks Harbor PAL), Maine central (Augusta PAL), and Northern Maine (Millinocket and Houlton PALs) respectively.|
|128.375, 135.2, 132.975||Yarmouth PAL for Moncton Centre. 135.2 is by far the most commonly used frequency. 128.375 generally is only active when traffic is concentrated far off-shore. 132.975 sees only limited use.|
|133.95||Halifax PAL for Moncton Centre. If you live near Halifax and can receive the ground side of this you will find that it simulcasts several other Moncton frequencies, i.e. you will hear the ground controller on this one and the aircraft side on another such as 125.25 (frequently) and others some of the time.|
|133.3, 133.7, 132.75, 125.25||Cape Breton PAL for Moncton Centre. 125.25 is commonly used by aircraft flying just offshore (or sometimes much farther offshore) whereas 132.75 is the most common frequency by those flying more or less along the length of the province. 133.7 is often used as a fill-in between these two frequencies, with 133.3 less commonly used.|
|127.125, 132.7||Moncton Centre at the Centre's own local site in Riverview.|
|132.8||Iles de la Madeleine PAL for Moncton Centre|
|135.05, 128.45, 119.425||Gander Oceanic Clearance Delivery PAL's in Stephenville, HF, Allan's Island, NF (south tip of Marystown Peninsula) and Sydney NS. These frequencies are used exclusively for passing clearances to aircraft proceeding eastwards across the Atlantic through Gander's area. Clearances are also passed over regular frequencies as well.|
|THE FOLLOWING FREQUENCIES WILL NOT GENERALLY BE HEARD FROM THE HALIFAX AREA EXCEPT IN UNUSUAL RECEPTION CONDITIONS OR WITH A LARGE-ARRAY BEAM ANTENNA.|
|126.325||Sept Iles PAL for Moncton Ctr. Some aircraft heading on a more northerly route might be passed to this frequency.|
|132.525||Moncton PAL at Natashquan, Quebec.|
|134.7, 132.05, 128.175, 125.075||Trepassey PAL for Gander Ctr. If you live in central Nova Scotia you might hear aircraft on these frequencies. These are the Gander frequencies aircraft are passed to as they proceed up the offshore rather than over the island of Newfoundland. 134.7 is the most common.|
Note that listeners in New Brunswick may be also able to listen to aircraft in contact with Montreal Centre, while those in north-eastern Nova Scotia will likely hear communications with Gander Centre: 132.6, 133.9 at Gander itself, and 133.55. 135.775 for the Stephenville PAL used mostly for aircraft passing up the west side of Newfoundland.
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.
Those who are interested in listening to high-flying aircraft, or even to pause and look up on a clear day, are fortunate to live in the Maritimes. While it is true that we have somewhat limited air traffic in and out of our airports, we certainly have no shortage of aircraft passing overhead. The busiest long-range air route in the world is the one connecting the East Coast corridor of the United States with Western Europe. While there are route variations depending on wind conditions it is basically true that on a typical day most aircraft pass along a long band of territory extending SW to NE (and vice versa) from Maine to Newfoundland and then out over the Atlantic. The width of the band is from around central New Brunswick and the eastern Gulf of St Lawrence on one side, and the offshore of Nova Scotia on the other. Of course there is other traffic farther north coming from or going to the US Midwest or Ontario and as well traffic to our south whose destination is in southern Europe such as Madrid, Rome or Athens. What we are talking about here in this page is mostly traffic between such cities as Boston, New York, Washington or Miami and European cities such as London, Paris, Geneva and Moscow. I will also be covering more localized traffic in and out of Halifax and going to or coming from Montreal and points west, or to Newfoundland.
At the risk of being repetitive, if you have read my other pages or are already more knowledgeable than I am, the first thing to realize is that most regularly scheduled air movements as well as many itinerant ones are subject to air traffic control (ATC). Over land, ATC relies on blanket radar coverage and VHF communications between the controllers and the pilots. Outside of the areas immediately around major airports there are basically two layers of ATC control: low and high; however there are subdivisions as well in some areas such as very high level. The altitude division between low level and high level does vary some from place to place but for this explanation I will use FL280 as the boundary. FL280 is approximately equal to 28,000 feet above sea level.
All traffic arriving at an airport or leaving from one, or merely travelling within a local or regional area will be in the low layer. So will aircraft that may be travelling long distances but for capability reasons or any other reason for that matter, will not be at or above FL280 will also be in the low system. By system I mean that they will be under the control of low level controllers using frequencies assigned to that service. It is also true that some low level aircraft will be on their own and not on routes that are controlled at all. On the other hand aircraft that have ascended to higher levels and therefore on longer routes and capable of it, will be using the high level ATC system. This is what I will be writing about here.
Before continuing with the main description I must also speak about trans-Oceanic flights and specifically the North Atlantic routes. Once an aircraft is approximately 200 km offshore the effectiveness of ground-based radar and of VHF radio begin to drop off and eventually are useless. An aircraft heading from let's say New York to London could stay in radar and VHF radio range almost continuously if the route was more or less from NYC to Labrador to southern Greenland to Iceland to the north of Scotland, but that is somewhat of a deviation from the shortest (great circle) route. It may be interesting to note that Gander has a remote transceiver site near the southern tip of Greenland to serve such northern traffic. For the most part however the traffic across the Atlantic will leave radar and VHF behind and transition to a system using both HF radio and as well today satellite communications. At present this means that controllers receive position reports and ETA's to designated spots, rather than having radar pictures of aircraft positions. Aircraft remain under control of ATC but the controllers do not actually see the aircraft on radar screens. Perhaps one day there will be satellites providing coverage from above. The North Atlantic routes are under ATC control from Gander Oceanic in Newfoundland (west half) and Shanwick Oceanic (east half). There are sets of HF radio frequencies for the Atlantic (as there are for all other areas of the world) but these are not receivable on a normal scanner and instead require a communications receiver capable of receiving SSB signals. Aircraft transiting the north Atlantic follow sets of tracks that vary from day to day depending on the position of the jet stream, that high level band of winds flowing more or less from west to east. Aircraft flying eastward should fly in the jetstream as it helps to propel the aircraft along, and save fuel and time. On the other hand, westbound aircraft should avoid the strong headwinds of the jetstream. Westbound aircraft are never helped by the winds and often are impeded, with the result that eastbound flights are quicker than westbound ones. For more explanation of the tracks and how they are determined check this Wiki article. The determination of tracks and the control of North Atlantic traffic is constantly evolving but currently is handled by a system developed by Nav Canada called GAATS (Gander Automated Air Traffic System) and SAATS (Shanwick Automated Air Traffic System). Generally speaking you will not be listening to aircraft being handed off from the overland (VHF and radar) ATC to the Oceanic system, as this mostly happens northeast of Nova Scotia and east of Newfoundland. There are exceptions however, with the main one being aircraft leaving from Halifax or Moncton and heading south more or less towards Bermuda and ultimately with destinations such as Cuba or the Dominican Republic. These aircraft will be handed off from VHF to HF off the coast of Nova Scotia and you will hear them being assigned two HF frequencies, one a primary and one a secondary or backup. These will be for communications with New York Oceanic. There are a range of frequencies in the spectrum from around 2.5 MHz to around 27 MHz and are assigned depending on the time of day and other conditions. Usually you will hear assignments around 8 or 11 MHz but at night you might hear lower and day you might hear higher frequencies being assigned.
If you have an interest in long distance HF aero frequencies here is a chart of the service areas of various frequency groups for the Atlantic and Caribbean areas:
|These frequency areas, part of the world-wide
MWARA system, are ones of primary interest to listeners in eastern
Canada, but you may also be able to hear some traffic emanating from
other areas. The named places are the sites of the major
ground radio facilities using the frequencies. Gander and
Shannon primarily used NAT B, C and F. B and C are for the
same area but due to high traffic are split between aircraft
registered in western and eastern countries. An aircraft
heading south from NS towards the Caribbean will be assigned to a
NAT-A frequency or possibly a NAT-E. Here are the most
relevant frequency groups (all are USB, expressed in kHz):
NAT-A: 3016 5598 8906 13306
As this is not the main topic of my page, I
will leave this to you if you are interested, to research further.
Listening to this system is not particularly interesting in its
content as it is mostly positions reports and requests to change
heading or altitude. For communications between aircraft
and companies re problems you should listen to LDOC frequencies
(Long Distance Operational Control) frequencies provided usually by
ARINC. For the Atlantic area you could try 3494
6640 8933 11342 13348 17925 21964 kHz;
however many major airlines now increasingly rely on satellite
Now back to what you can hear on your scanner, and perhaps see as well.
The two main pieces of information you must be aware of are as follows: First of all, and there are exceptions, most traffic westbound will be in the daytime our time. Travellers leave Europe in the morning or early afternoon, and due to time zone differences arrive in eastern North American cities in the late afternoon, too late for business that day but with an adjustment sleep in a hotel. On the other hand most of the eastbound flights will be in the evening and overnight our time. This is designed for business people to do a day of work in an American east coast city and board an aircraft in the early evening, sleep if possible on the way, and arrive in Europe in the morning European time. In addition this means that an aircraft can fly to the east coast USA, drop off passengers, and after a short layover, return to Europe without an overnight stop in Boston or Philadelphia. This is not a hard and fast rule as considerable numbers of aircraft fly the opposite direction to these main waves and this will include military, cargo, general aviation and charter passenger flights.
Secondly, due to the daily assignment of tracks as discussed above, you may find that on a particular day much of the traffic is off the coast of Nova Scotia and using the VHF frequencies assigned for that area, whereas another day it may mostly up the central spine of Nova Scotia, or farther north over New Brunswick. Regardless of where the bulk of the traffic is for that day, there are always odd cases in the other zones, depending on origin and destination.
Let us take the typical situation of an aircraft coming up from the Gulf of Maine and heading up the middle of Nova Scotia. You are not going to hear anything particularly interesting unless something goes wrong. You might hear the aircraft on 133.45 or 134.95 acknowledging a directive from Boston Center to switch to Moncton Centre on 135.2, which is Moncton's main Yarmouth area PAL. Then the aircraft will come up on that frequency with a short statement like this: "Moncton, United 100, Flight Level 380". Moncton will acknowledge and usually that is all until halfway up Nova Scotia where Moncton will pass them over to the next Moncton sector on 132.75 or maybe 125.25 both based in Sydney. There is a Moncton PAL in Halifax but that is usually used for far offshore traffic as there is no need of it over NS due to the overlapping coverage of the Sydney and Yarmouth facilities. Many times the checking-in pilot will also give a short statement of the ride (turbulence conditions), such as "light chop" which is one step above "smooth" an and a step below "light turbulence" or perhaps "moderate turbulence". I am not aware of the exact definitions of these descriptors. You will often hear pilots requesting a change in altitude due usually to the turbulence encountered at the present altitude. PIREPS (pilot reports) are routinely passed on to other aircraft approaching the position in question, so that the other pilots may request altitude changes before the conditions are encountered. Pilots do sometimes request horizontal deviations but these are relatively uncommon at high altitudes due to being above most weather, and as well it is necessary to remain within assigned tracks.
HIGH-FLYING AIRCRAFT other than those transiting between NE USA and Europe
In addition to aircraft simply passing over the Maritimes to and from Europe, there are also those that are arriving at, or leaving from Maritimes airports on routes to and from points in Newfoundland, along the US eastern seaboard, or inland. These are the aircraft that you can follow on local frequencies and then on the low level centre frequencies, and then as they ascend, they switch over to the appropriate high level frequencies as described above. This would opposite in progression for those heading into Halifax or other airport. For example an aircraft heading to Toronto from Halifax would first be heard on the appropriate Halifax airport frequencies, then terminal on 119.2, then 124.3 or 132.2 or 132.5 low level centre, then on to 127.125 over southern New Brunswick, and then over to Boston Center 128.05. If you live in Halifax and you have a good enough antenna, perhaps a beam, you might then hear it later switch to a Montreal Centre frequency as it leaves US airspace.
Direct observation of overflying
aircraft. For most of us the best direct indication of a
high-flying aircraft is its contrail. Contrails are present only
in certain conditions but are very common and we are all familiar with
them. They can originate from the engines, in which case there
will be one from each engine and seen clearly with binoculars or even with
the naked eye as separate streams. Contrails can also
originate from the winglets found on the tips of some aircraft wings, and is
a result of the air pressure changes caused as the winglet cut through and
deflect the air. Here is the
wiki page on contrails.
We of course can also hear the sound of aircraft passing high overhead but
the sound as you realize does seem to follow behind the the aircraft and it
may be difficult to pick out an aircraft not producing a contrail.
On the other hand there are times when the sun is in the right position in
relation to the aircraft, near sunrise and sunset, when the aircraft is
Indirect observation and identification via radar reception. It is possible currently for individuals to acquire hardware and software that turns a personal computer into a simulated radar screen. One of the current "radar boxes" is the AirNav Systems Radar Box. See here for information. Essentially these boxes receive the radar transponder signals transmitted by many commercial aircraft. These are the same signals received by ATC in order to show aircraft positions and identifications on their radar screens.
Seeing aircraft traffic on the web. It is easy to watch real-time or slightly delayed depictions of civil aircraft positions on the web. You will not see all aircraft but you will see most, depending on the site you use. Go to my specialized page for more information. Knowing that something is heading towards your location will give you the chance to get out and see it, or even photograph it, and not only that, you will know what it is, and where it is going. The information for these sites comes either from official sources, or from ordinary people who have the radar boxes mentioned just previously and allow their information to be networked.
Photographing high-flying aircraft. It is possible to take photos of aircraft flying at high altitude over your location but you will need an appropriate accessory lens and a camera body that can take it. The photo at the head of this page is by Howard in Yarmouth. The following photo is by Darryl A, taken with a DSLR with a 250mm lens. This is a USAF C-17 passing above the Halifax area and is doubly interesting due to the shadow of the tail appearing on the contrail. This aircraft is most likely about to be refuelled or has just completed doing so and therefore is not flying as high as the usual airliner traffic that is at about 35000 feet and up. Darryl and Howard are part of an informal group of enthusiasts who use the scanner to track and observe refuelling activities in our region. Check my air refuelling page for more information.
To the right is a shot taken by myself in a first time effort with my Canon PowerShot S5IS with stock zoom lens set at maximum optical zoom. I avoid taking photos using the digital zoom component. This is of Air France's A340-200 F-GLZU enroute from Boston to Paris at 35,000 feet AT 1920 local time on June 13, 2012. and flying above Halifax. You will readily observe that this is nothing compared to the telephoto shots you have already seen on this page, but can still be fun to do. I like the "aloneness" of the aircraft in such a shot. I doubt I will ever be able to purchase a telephoto lens so will continue to take the occasional photo like this.