Definition
A dedicated electrical distribution bar that supplies power exclusively to the aircraft's avionics equipment, such as radios, navigation receivers, transponders, and flight displays. It is normally isolated from the main electrical bus by an avionics master switch or relay, allowing the avionics to be powered down independently to protect them from voltage spikes during engine start and shutdown.
Plain English
A separate power line in the airplane that feeds only the radios, navigation gear, and other electronic equipment, so they can be switched on or off as a group without affecting the rest of the airplane's electrical system.
Context Anchor
Seen in airplane electrical system descriptions, checklist procedures, circuit breaker panels, and abnormal procedures for turboprop airplanes.
Derivation
Avionics' combines 'aviation' and 'electronics' — the electronic equipment used in aircraft. 'Bus' comes from the electrical engineering term 'busbar,' a metal bar that distributes power to multiple circuits. So an avionics bus is literally the power distribution bar dedicated to the electronic equipment.
Why Pilots Care
Keeps navigation and communication equipment operating on clean, stable power even when other systems draw heavy current.
Analogy
Think of it like a power strip for aircraft electronics. The airplane’s electrical system feeds the strip, and the radios, displays, and other electronic equipment receive power from it.
Intuition Check
Do not picture a passenger bus or a moving vehicle. In an electrical system, a bus is a shared power path that feeds several pieces of equipment.
Example Sentence 1
After starting the engine and confirming stable voltage, the pilot turned on the avionics master to energize the avionics bus.
Example Sentence 2
A short on the avionics bus can blank the navigation displays while the engine instruments remain lit.