Aeronautical Radio

As it Pertains to Listening to Aircraft in the Maritimes Area of Canada

Last updated in January 2017.  Frequency list not as current.

Aero Radio Basics  

Aeronautical Radio is divided into several parts of the radio spectrum.  At the low end there remain radio beacons in the low and medium frequencies (200 to 400 kHz) and as well some navigation aids operating at or above 900 MHz.  In both cases these are of no direct importance to someone listening to aircraft and therefore will not be described below.   Here are the three bands of most importance:

VHF:  This is the big one, at least as far as what I am talking about here. Over land or within a few hundred kilometres, civilian aircraft will normally use VHF.  This is on the band between 108 and 137 MHz.  The section between 108 and 118 MHz is principally for the navigation aids but some of these do have voice broadcasts, but you will not hear two-way communications in that section.  The section between 136 and 137 is a relatively recent addition and you will find very little activity locally in this range.   In North America there is currently a 25 kHz spacing between channels and therefore there are 760 distinct frequencies in the range 118.0 to 136.975 kHz.   Note that in Europe all aircraft are required to have radios capable of 8.33 kHz spacing and therefore three times as many channels!  This may come to North America someday, but that day is not yet in sight. 

Note also that the band is divided into segments differentiated between two usage categories.  One is what might be termed commercial business use.  The other is air traffic control and similar usage.  Within the overall 118 to 137 band these sections are allocated frequency by frequency to private entitities:   128.825 to 132.000 MHz   plus the recently added 136 to 136.975 segment.   These entities include airlines, FBO's, special usage organizations, and AIRINC.  AIRINC is the American company that operates radio communications jointly for many of the airlines.     The remainder of the spectrum is used by (or allocated by) the various national air control agencies for such uses as tower, ground, emergency communications, SAR coordination, Unicoms, area control centres, etc.   

While I will be saying more on the topic within specific pages, it is useful to mention now that reception of VHF ground stations is normally quite limited, depending on relative elevation and antenna, but 50 km would be excellent or even exceptional.    Reception of aircraft depends principally on the altitude of the aircraft.  I can only occasionally hear aircraft on the ground at Halifax Airport, about 20 km from me, but I can regularly hear airliners over the Gulf of Maine, and that with an external antenna that is not cut for the band.   Note that this band is also used far away from land by pilots simply wishing to talk to one another.  The range between two high-flying aircraft may be very long due to the line-of-sight factor.    While this is a civilian band, you will find that in our area at least, military aircraft also use it as they fly like civilian aircraft along the recognized air routes and land and depart at civil airports.

UHF:  This band, between 225 and 400 MHz, is reserved for military use around the world, and hence is commonly referred to as the “milair band”.  In this band today you can hear not only aircraft but also terrestrial military trunk systems (though none around this region), and a lingering use by naval ships for intership communications.   This band is not one I regularly monitor, but I do have many frequencies programmed in, and on occasion will listen.  Note that this band is not even in a lot of scanners.   If you intend to monitor the two military airfields in this region, you should include “milair”.   You will also hear this band come alive during exercises that are occasionally held in the coastal areas.    I would say that the most interesting and consistent use of the band is in relation to air-to-air refueling that takes place regularly above Nova Scotia.    During these procedures by USAF units the aircraft will be in communication with the civil air traffic controllers on the VHF band, but will speak among themselves on UHF.   I do have a specific page on refueling here on this site, but I am no expert on the topic.    Within that page I do direct you to an active forum on radioreference where you can keep up to date and learn from the experts.

HF: The high frequency aero bands are discontinuous sections of the overall HF band between 3 and 30 MHz.  In fact there are a few frequencies just below 3 MHz that technically therefore are in the very high end of the MF band.  I am not intending in this website to cover the HF bands.  These are not receivable on a scanner but rather require a communications receiver capable of USB detection.   Aeronautical HF is commonly used for long distance communications once an aircraft is beyond the range of VHF and UHF ground stations.   These communications are generally of two types.  One is to remain in contact with controllers as they cross oceanic areas, and the other is to be in contact with their company for operational reasons such as maintenance issues.   HF is to some extent being supplanted gradually by satellite communications but is far from dead.   Each part of the world has specific frequencies assigned for communications with ground controllers, and which ones are actually in use depends on propagation conditions, with the main factor being time of day.    Also in this band are continuously operating VOLMET or weather broadcast stations located around the world. 
These are an enjoyable way to check propagation conditions or to log unusual countries.   In our area it is most common to hear New York, Gander and Shannon Radios, but you might be lucky enough to hear places like Dakar or Hong Kong.   There are also military counterparts to these, such as Trenton in Ontario.   One of my best catches in my earlier days of radio listening was Wake Radio from the middle of the Pacific, a station that does not even exist any longer.   I will leave you, if you are interested, to go on your own to research and get involved in HF, and will say little more about it here.

VHF Frequency Usage

The following is a frequency table for the Maritimes and New England area, with some standard national and international uses also included.  It is intended to be a VHF table but some UHF is included.   At this point it is somewhat out of date, but little changes over time, so will remain useful.   

Terminology:

VOR = vertical omnirange - A VHF nav beacon indicating direction

Terminal = arrival and departure control vicinity of airport.   Often referred to as "Arrival" or "Departure" depending on what the aircraft is doing.  In the Maritimes only Halifax, Greenwood and Moncton have terminal control units, and these do not operate during the quiet overnight hours.

Unicom = Usually there is a private ground station that may give advice or info but not control of aircraft.  Aircraft may be required to announce intentions on this freq. Aircraft doing so will use the term "Traffic".   In some areas the ATF frequency is referred to as a unicom. 

ATF (Airfield Traffic Freq) = official term for "traffic" where no ground station. 

Ramp Advisory Frequency:  A frequency used by pilots to coordinate movements on the ramp. These were present at Halifax and Moncton in this region but have been discontinued.  Similar to an ATF as there is no controller, but may not be absolutely mandatory to announce intentions.

HIPAL = Peripheral (Remote) transceiver serving high altitude aircraft.  For example, Moncton Centre has a peripheral transmitter near Halifax on 133.95 MHz.

LOPAL = Peripheral (Remote) transceiver serving low altitude aircraft.

Centre =  An Area Control Centre that controls flights in a large area, other than actually at the controlled airports or in Terminal Areas.  The centre for the Maritimes is Moncton Centre located in Riverview, New Brunswick.   Adjacent centres are Boston, Montreal and Gander.  Note that in the USA the word is spelled "center" and instead of being called an ACC, they are called Air Route Traffic Control Centers (ARTCC).

760 channel chart will go here, but not yet!