Basic Conventions for Aircraft Monitors
- One-Sided Conversations: Because aircraft fly high above the
ground, their transmissions have much more range than the ground stations with whom
they're talking. This means that only the airborne side of most conversations will be
heard. Is this a problem? Not for me. First, you miss very little in these conversations
because pilots are required to repeat back to controllers any instructions or frequencies
that they are given. In fact, hearing only the aircraft has tremendous advantages. It
helps the listener to avoid mixups among simulcast ground stations, and is a terrific help
in isolating military aircraft from other traffic
- Frequency Bands Used: Although the air band is 108-137 MHz,
almost all civilian voice communications are above 118 MHz. In addition, the military has
138-150 MHz, 225-400 MHz, and 30-88 MHz (FM).
- Sources of Information: The best place for you to get information
is the same place where the pilots go. Your first purchase should a NOAA Sectional
Aeronautical Chart for your area. Check out the Aircraft
Bibliography.
- There are two types of flight for scanning purposes: Visual
Flight Rules (VFR) involve navigation by landmarks and dead reckoning. No radio
contact with anyone is necessary unless in controlled airspace or at a public airport. Instrument
Flight Rules (IFR) govern preplanned flights along established routes, using radio
navigation aids. IFR flights must maintain radio contact with air traffic controllers at
all times.
- Types of Airspace: There are two types of airspace as far as
scanner listeners are concerned. These are controlled (radio contact mandatory)
and uncontrolled (radio contact not mandatory). Everything above 18,000 feet is
controlled. Below that, air traffic control is optional except for blocks of controlled
airspace which are scattered around like bushes and trees in your backyard. And like
bushes and trees, those blocks of airspace have three dimensional shapes that uncontrolled
aircraft might be able to fly above, below, around or through.
- Always think in three dimensions: Aircraft flying over the same
spot on the map may be using different frequencies, depending on their altitude. Even out
in the open, the Air Route Traffic Control Centers have different frequencies for planes
that are above and below 23,000 feet. It's smart to understand the airspace system,
particularly for fighter plane buffs.