Final answer:
The Avionics Master switch serves to control the power supply to an aircraft's avionics equipment, allowing for protection against electrical surges during start-up and shutdown and providing safety in emergency situations.
Step-by-step explanation:
The Avionics Master switch is a crucial component in aircraft electrical systems, designed to enhance the safety and management of the airplane's electronics. The primary purpose of this switch is to allow pilots to control the power supply to all avionics equipment with a single action. This function is particularly important during emergency situations or as a standard procedure during start-up and shutdown processes to prevent damage to sensitive avionics caused by electrical surges. By isolating the avionics from the electrical system, pilots can ensure that these sophisticated and essential instruments remain protected and functional when needed.