What activates the emergency lighting system in an aircraft?

The emergency lighting system in an aircraft is specifically designed to activate in the event of a loss of normal aircraft power. This system is crucial for ensuring passenger safety during emergency situations, as it helps illuminate escape routes and exits when the usual cabin lighting may fail.

When normal power is lost, it signals the need for emergency systems to come online, ensuring that there is sufficient visibility for passengers and crew to evacuate the aircraft safely. The lighting system operates independently of the main power supply, relying on backup batteries or alternative power sources to remain functional during such incidents.

Other scenarios like normal operations of aircraft power, pressing an emergency button, or smoke detection do not inherently trigger the emergency lighting, as those systems are designed to function under normal conditions or rely on specific triggers that do not represent a total power failure. Thus, the activation during a power loss is critical to emergency preparedness and passenger safety.