Definition
A cockpit control, typically a rotary switch on the audio panel, that determines which radio transmitter is connected to the pilot's microphone. When the pilot keys the mic, the audio is sent out through whichever radio the transmitter selector is currently pointing to.
Plain English
A switch in the cockpit that picks which radio your microphone will talk through when you press the push-to-talk button.
Context Anchor
Seen on aircraft audio panels and communication radio controls when choosing which radio to use for a call.
Derivation
“Transmitter” comes from a word meaning “to send across.” “Selector” means something that chooses. Together, the term points to a control that chooses which radio will send your voice out.
Why Pilots Care
Selecting the wrong transmitter can send your call on the incorrect frequency, resulting in no reply from ATC or other aircraft.
Intuition Check
Do not assume the transmitter selector controls everything you hear. It mainly chooses which radio your microphone uses to transmit.
Example Sentence 1
Before calling ground, she glanced at the audio panel and confirmed the transmitter selector was set to COM 1.
Example Sentence 2
After switching frequencies, she turned the transmitter selector to the active radio to make the position report.