Definition
A brief, sudden surge of electrical voltage that rises far above the normal operating level of a circuit and then collapses, typically lasting only microseconds to milliseconds. Voltage spikes are commonly produced when current flow through an inductive component (such as a relay coil, solenoid, or motor winding) is suddenly interrupted, causing the collapsing magnetic field to induce a high-voltage transient.
Plain English
A very short, very sharp jump in voltage that is much higher than normal. It happens fast, then is gone, but it can damage sensitive electronics in the airplane.
Context Anchor
Seen in aircraft electrical system discussions, especially when troubleshooting alternators, generators, switches, batteries, radios, lights, and sensitive electronic equipment.
Derivation
The word 'spike' comes from the shape of the event when drawn on a graph of voltage over time — a tall, narrow point that looks like the spike of a nail. The image describes the behavior: a sharp rise and fall.
Why Pilots Care
Unprotected spikes can destroy avionics, navigation equipment, or flight instruments, leading to failures or emergency landings.
Analogy
A voltage spike is like a quick slap to an electrical system, not a steady push. Even though it is brief, the hit can still damage delicate equipment.
Grounding Statement
Picture a radio working normally, then receiving a split-second burst of too much electrical force when a switch is moved or a power source changes.
Intuition Check
A voltage spike does not mean the voltage stayed high for a long time. It means the voltage jumped up suddenly and briefly above its normal level.
Example Sentence 1
The avionics master switch is turned off before starting the engine to protect the radios from a voltage spike.
Example Sentence 2
After a nearby lightning strike the pilot had the wiring inspected for any voltage spikes that might have damaged the radios.