Final answer:
The AC ESS FEED pb white ALT light indicates the status of the auxiliary feed pump in an aircraft's fuel system.
Step-by-step explanation:
The AC ESS FEED pb white ALT light is an indicator light that is commonly found on aircraft control panels. It is used to indicate the status of the auxiliary feed pump (AC ESS FEED Pump). The AC ESS FEED Pump is responsible for supplying fuel to the aircraft's engines in the event of a failure in the main fuel supply system.
When the AC ESS FEED pb white ALT light is illuminated, it typically means that the AC ESS FEED Pump has been activated and is supplying fuel to the engines. This could be due to a failure in the main fuel supply system or as a precautionary measure during certain flight conditions.
It is important to note that the specific meaning of indicator lights can vary between different aircraft models, so it is always best to consult the aircraft's manual or a certified technician for accurate information.