N4JRI's Radio Pages:  Aircraft Monitoring

Scanning the Airlines

Scanning the airlines is a terrific undertaking, because it's still one of the things that we have to do for ourselves without the help of government publications. There are several basic things that you should know about the airlines before getting started in this area.

Frequency Bands:

• 128.850-132.000 - This is the primary VHF band for communications among the airlines. There are some additional frequencies now allocated in the range 136.500-136.975 - Not all frequencies in this band are for the airlines, but this would be the basic search range.

• HF Airline bands will be added at a later time.

Identification:  While airliners clearly identify themselves on most frequencies, there is no need to include the airline name while talking on the airline's own frequencies. Most aircraft that call in on  frequencies assigned to their own airline simply identify with their flight number.

Airline Ground Crews:  The frequency range of 460.650-460.875 is set aside for use by airlines when within 20 miles of an airport. ARINC also has licensed 800 MHz trunked systems for the airlines to share at some of the larger airports.

Usage of Airline Frequencies:  Many users of VHF-AM voice frequencies today are the small commuter airlines that work in concert with the big boys. You'll also find fixed-base operators, private hangars for corporate aircraft, and some other special-use outfits on these frequencies. Variety is the spice of life, and you find plenty of that here. The airlines usually have ARINC radios at their gates at various airports and their maintenance facilities. They may also be able to patch through to a central dispatcher on a gate or maintenance frequency, or on a separate frequency altogether. Finally, there is a nationwide network of ground stations which pilots address as 'San Francisco Radio' which keeps them in touch with whomever they need. Eastern Airlines ran a competing system called "Atlanta Radio" but this died soon after the airline did.

Aeronautical Radio, Inc. (ARINC) - A private company owned and operated by the airlines, and located in Annapolis, MD.. Most VHF-AM and HF-SSB frequencies used by the airlines are licensed by the FCC to ARINC, and this is how they are listed in FCC publications. ARINC also operates the US Air Force's global HF system, and operates 800 Mhz trunking systems at some larger airports for the joint use of airline ground crews. The only lines I'm aware of that don't participate in ARINC are very small local airlines, which can be licensed under their own names on 122.825 and 122.875.

• Aircraft Communications Addressing and Reporting System (ACARS) - This is a digital air/ground communication mode that takes place over selected VHF-AM radio frequencies. The larger airlines have moved most of their routine communications to this rather than voice channels, and they can even communicate with the FAA via this system. It's helped to make the voice frequencies fairly quiet as opposed to the days when every airliner checked in with their desk 20 minutes before arrival. Software is available for decoding ACARS messages on home computers. Frequencies include (I think) 131.550, 130.025 and 129.125.

• ARINC  VHF Air/Ground Enroute System - System of VHF radio outlets around the US, providing aircraft with communication service for their operational (as opposed to navigational) needs.

• High Frequency Data Link (HFDL) - As its name suggests, this is ARINCs foray into data links on the HF bands.

ARINC Frequency List - A project to collect the best info we can. Consider it under construction for the time being.

Later on, we'll have some lists of frequencies to help give you a feel for what's out there.

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