Radio communications

This is a very basic guide to aviation communications. You won't find here the procedure to call an airport when you're on approach, for example. However you will find which range of frequencies to listen to approach, if you are an aviation enthusiast and have a scanner. You will find how the aircraft identify themselves on the radio with the callsigns, and other useful information. Enjoy!

Frequency ranges

VHF mHz
108.000-117.975   Navigational aids
118.000-121.400   Control towers
121.500           International emergency frequency
121.600-122.900   Ground and apron control
122.700-123.900   UNICOM frequencies
123.450           Air to air communications
124.000-128.800   Arrivals and departures
129.000-131.775   Company operations
132.000-135.975   ATC Center (enroute control)

UHF mHz
225.000-400.000   Military traffic (mostly)
243.000           International emergency frequency

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Phonetic alphabet/Numbers

Alpha Bravo Charlie Delta Echo Foxtrot Golf	Hotel India Juliett Kilo Lima Mike November	Oscar Papa Quebec Romeo Sierra Tango Uniform	Victor Whiskey X-ray Yankee Zulu
1 One 2 Too 3 Tree	4 Fower 5 Fife 6 Six	7 Seven 8 Ate 9 Niner	0 Zero

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Figures

UTC - Coordinated Universal Time
UTC is expressed in the 24-hour time format, followed by the word Zulu.
Example: 6PM UTC becomes 1800Z
On the radio, this would be expressed as "One Eight Zero Zero Zulu"

Altitudes
Altitudes below 18,000 ft. are expressed in hundreds or thousands of feet:

 8,000 ft. - "Eight Thousand"
10,000 ft. - "One Zero Thousand"
14,600 ft. - "One Four Thousand Six Hundred"

Altitude of 18,000 ft. and more are expressed as "Flight levels" (FL):

20,000 ft. - "Flight Level Two Zero Zero"
28,000 ft. - "Flight Level Two Eight Zero"
30,400 ft. - "Flight Level Three Zero Decimal Four"
             "Flight Level Thirty Point Four"

Winds, airspeed...
This is how you or the ATC control should state, respectively, wind speed before take-off or landing, a traffic advisory, a heading or an airspeed.

Winds coming from bearing 090 (East), 12 knots:
    "Winds: Zero Niner Zero at One Two"

Traffic at the right handside, 1000 feet above you:
    "Traffic at three o'clock, one thousand feet above you"

Heading 270 (West)  (all numbers pronounced one by one):
    "Heading Two Seven Zero"

Reduce speed to 150 knots:
    "Reduce speed to One Five Zero knots"

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Aircraft callsigns

General aviation aircraft
These aircraft include private aircraft, or belonging to a large corporation. At first, the callsign is the entire registration code (e.g. N234S for a aircraft registered in the USA) for the first transmission. After a couple of transmissions, the last two or three characters can be used. Sometimes the callsign is the aircraft's model followed by the last two or three characters of the registration code

Private Cessna Citation, registration N1451W:
   "November One Four Five One Whisky"
   "Citation Five One Whisky"

Private Raytheon King Air, registration N18769:
   "November One Eight Seven Six Niner"
   "King Air Seven Six Niner"

Private Cessna 411, registration C-FFTG:
   "Charlie Foxtrot Foxtrot Tango Golf"
   "Twin Cessna (Foxtrot) Tango Golf"

Private Boeing 707, registration N2811S:
   "November Two Eight One One Sierra"
   "(November) Eleven Sierra"

Private Mitsubishi MU-2, registration JA8845:
   "Juliet Alpha Eight Eight Four Five"
   "Mitsubishi Eight Four Five"

Commercial aircraft
The flight number is used as reference, preceeded by what is called the airline's callsign, and followed by the word "Heavy" if it is an aircraft capable of generating a large amount of wake turbulence (see the glossary). Once the identification is done, after a couple of transmissions, the word "Heavy" can be left out, and for expedited communications, the airline's callsign can be ommited.

Air Canada flight ACA870, an Airbus A330:
   "Air Canada Eight Seven Oh Heavy"

Air France flight AFR1561, an Airbus A320:
   "Air France Fifteen Sixty-One"

British Airways flight BAW592, a Boeing 747-400:
   "Speedbird Five Ninety-Two Heavy"

Military aircraft
Among the most important military callsigns, there is of course "Air Force One", which identifies any aircraft carrying the President of the United States. In the case of a helicopter, it becomes "Marine One". The pattern is similar for other types of transports. The "One" is replaced by "Two" when the aircraft is carrying the Vice President: "Air Force Two", "Marine Two", etc. In the case of members of the President or Vice President's family, the callsigns used are "Executive One Foxtrot" or "Executive Two Foxtrot".

In many countries, military aircraft use "tactical callsigns" which differ depending on the mission, followed by a series of numbers. Some other examples include: "Liberty 24", "Voter 51", "Kasey 15", "Top Gun 71", "Jolly 31", "Navy Rescue 18".

Aircraft in the Force's passenger fleet (used, for example, for flying in VIPs or diplomats) often bear civilian-type callsigns. For example, in the Canadian Forces, it could be "Canforce 814".

Priority handling
The usage of the callsign prefix "Lifeguard" indicates a priority status of the aircraft in what could be called a life-or-death mission, i.e. transportation of time-sensitive cargo (such as organs for transplants) or medical emergencies. Example: "Lifeguard TWA 800 Heavy" (the real flight 800 involved in the 1996 Long Island crash had the "Lifeguard" prefix).

Medical voluntary flights that require some kind of priority status (however not as high as "Lifeguard") use another special callsign. The Air Care Alliance and the FAA defined "Compassion" as the callsign prefix to be used for such flights, followed by the last three characters of the aircraft's registration. N1234X would become "Compassion 34 X-ray" and would be displayed as CMF34X on flight plans and radar scopes.

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