Definition
A device or circuit that combines several separate input signals into a single output signal carried over one shared channel, allowing one line, frequency, or data path to handle multiple sources at once. In aviation systems, multiplexors are used in avionics data buses, communication links, and radar/surveillance networks to consolidate many information streams into a single transmission path.
Plain English
A device that takes several signals coming in from different sources and merges them so they can all travel down the same wire or radio link, instead of needing one line for each signal.
Context Anchor
Seen in aircraft electrical, electronic, and avionics system descriptions where many sensor or control signals must be handled efficiently.
Derivation
From 'multi-' (many) and 'plex' (Latin plexus, meaning 'fold' or 'braid'). The word literally suggests 'many folded together' — many signals braided into one channel. The '-or' ending names the device that does it.
Why Pilots Care
Reduces total aircraft wiring weight and complexity while maintaining reliable data flow between sensors, computers, and displays.
Analogy
Like a single highway with multiple on-ramps feeding traffic into one lane, where the cars are kept in order so they can be sorted out again at the other end.
Intuition Check
Do not read MUX as a display or instrument by itself. It is usually a behind-the-scenes electronic part that routes or combines signals for other equipment to use.
Example Sentence 1
Modern aircraft data buses use a multiplexor so that dozens of sensor readings can share a single wire instead of running individual cables to each instrument.
Example Sentence 2
During preflight, the technician verified that the MUX was routing all sensor inputs correctly over the shared data line.