In article .com,
wrote:

Any contactor has a coil, the starter has several coils, and
the alternator has a field coil. All coils create a sharp voltage
spike when the current is cut off. Switching the master off, the
alternator off, or releasing the start switch all create that spike
(I've measured the master contactor's spike at 600 volts) and those
expensive radios aren't all built to put up with it, especially
considering that the spike creates an electron flow in the wrong
direction through the bus. That's why many aircraft have an avionics
master switch (that has no coil involved). The rest should have the
radios shut off before shutdown.

Coils (inductors) are current storage devices.
Capacitors are voltage storage devices.