What type of circuit breaker may not be used in an aircraft?

In aircraft systems, the use of circuit breakers is critical for maintaining safety and functioning correctly. An automatic resetting circuit breaker, which resets itself after tripping, may not be suitable for aircraft due to several reasons related to safety and reliability.

Automatic resetting can pose a significant safety risk, as it could allow electrical faults or overloads to go unnoticed and cause further damage or create hazardous conditions on board. In the event of a fault, it is essential for the pilot or crew to be aware of the issue and take corrective action. A circuit breaker that resets automatically does not provide that awareness and could lead to situations where critical systems are compromised without the crew's knowledge.

Conversely, manual resetting circuit breakers require an intentional action from the pilot or maintenance personnel to reset them after a fault has been cleared, ensuring that the issue is acknowledged and addressed before the system is re-energized. Thermal and magnetic circuit breakers can be part of an aircraft's electrical systems but generally offer the critical safety features necessary for reliable operation.