What is the accuracy duration of the standby attitude indicator when all electrical power is off?

The standby attitude indicator is designed to provide accurate information regarding an aircraft's orientation even when all electrical power is lost. The key aspect of the correct answer is the specified accuracy and duration it maintains when operational power is absent.

When the electrical power is completely turned off, the standby attitude indicator retains a specific level of accuracy in its readings for a limited duration due to its internal mechanisms, which may involve gyroscopic principles. In this case, maintaining a 6-degree accuracy for a duration of 9 minutes indicates that while the instrument can provide reliable data about the aircraft’s attitude in the short term, its precision diminishes over time as the system is not receiving the necessary updates from electrical power.

This means pilots can rely on the information from the standby attitude indicator for navigating during a temporary loss of electrical power, but they should understand that this reliability will decrease with time, making it crucial for safe flight operations. The duration and the degree of accuracy provided by the standby indicator are critical for effective decision-making in emergency situations, which is reflected in the context of flight safety and navigation standards.