Definition
Not occurring at the same time or rate; describing events, signals, or processes that are not synchronized to a common timing reference. In aviation electronics and data systems, asynchronous communication transmits data without a shared clock signal between sender and receiver, instead using start and stop bits to mark each unit of data.
Plain English
Things that happen independently of each other rather than being locked together in time. Each event runs on its own schedule.
Context Anchor
Seen in avionics, electrical systems, data communication, and system-description material when timing between signals or actions matters.
Derivation
From Greek 'a-' meaning 'not,' and 'synchronous' from 'syn-' (together) and 'chronos' (time). Literally 'not together in time.' Knowing the root makes the meaning easy to hold: anything labeled asynchronous is simply not time-locked to something else.
Why Pilots Care
Some avionics and data systems use asynchronous communication, while others require precise timing. Understanding the difference helps when troubleshooting equipment or interpreting system behavior described in maintenance manuals and avionics documentation.
Intuition Check
Asynchronous does not mean random or automatically wrong. It means not tied to the same timing as something else.
Example Sentence 1
The data link between the two avionics units is asynchronous, so each transmission carries its own start and stop markers.
Example Sentence 2
Asynchronous signals from the sensors required separate processing before the display updated.