Definition
An electromagnetic switch in the aircraft starting circuit that, when energized by the pilot turning the ignition key or pressing the start switch, closes a heavy-duty contact to send high current from the battery to the starter motor.
Plain English
A small electric switch that uses a magnetic coil to flip a much bigger switch, allowing a strong burst of electricity from the battery to reach the starter motor and crank the engine.
Context Anchor
Seen in engine starting system descriptions, especially when tracing how power moves from the battery to the starter motor during engine start.
Derivation
Solenoid comes from the Greek 'solen' meaning 'pipe' or 'channel,' referring to a coil of wire wound into a tube shape. When current flows through the coil, it creates a magnetic field that pulls a metal plunger, which in turn closes the heavy electrical contacts. The 'starting' part simply identifies its job in the starter circuit.
Why Pilots Care
It keeps thick, high-current cables short and safe while allowing light cockpit wiring to control the starter.
Analogy
Think of it like a light switch with a remote control. The pilot's small key switch sends a little signal, and the solenoid does the heavy work of connecting the battery's full power to the starter.
Intuition Check
Do not assume the cockpit start switch sends full starter power directly to the starter motor. The start switch usually commands the starting solenoid, and the solenoid handles the heavier electrical load.
Example Sentence 1
When the pilot turned the key to START, the starting solenoid clicked and engaged, sending battery current to the starter motor.
Example Sentence 2
A worn starting solenoid can click but fail to crank the engine even with a fully charged battery.