Definition
COM1 is the label for the primary VHF communication radio in an aircraft, used to transmit and receive voice communications with air traffic control, flight service stations, and other aircraft on assigned frequencies. When two communication radios are installed, they are typically labeled COM1 and COM2, with COM1 normally selected as the active radio for the current controlling agency.
Plain English
COM1 is the name given to the first of the airplane's voice radios. Pilots use it to talk to controllers and other pilots. If the airplane has a second radio, that one is called COM2.
Context Anchor
You see COM1 on radio displays, audio panels, avionics screens, and checklists when choosing which radio to use for communication.
Derivation
COM is short for 'communication' and the '1' simply marks it as the first of potentially two or more comm radios. The numbering convention lets pilots and manuals refer to a specific radio without ambiguity.
Why Pilots Care
It provides the primary channel for receiving clearances, traffic advisories, and weather information essential to safe flight.
Intuition Check
COM1 is not a specific frequency. It is the name of the first communication radio or the selection that connects you to that radio.
Example Sentence 1
Tune the new center frequency on COM2 and switch to it once the controller hands you off, leaving the previous frequency on COM1 as a backup.
Example Sentence 2
When the primary radio became busy, the student switched to COM2 while leaving COM1 tuned to the current controller.