When should you cage the standby attitude indicator?

Caging the standby attitude indicator is an important procedure to ensure its proper operation, particularly when transitioning between power states. The correct time to cage the standby attitude indicator is before applying or removing electrical power, as well as before engine start or shutdown. This action helps set the gyroscope and prevents precession errors from occurring due to sudden changes in power, which can affect the accuracy of the indicator.

When you cage the instrument, you stabilize its internal gyroscopic mechanism, allowing it to reset and recalibrate. This is especially critical during the power-up sequence and after shutdown when the aircraft's systems are coming online or going offline. Not performing this step at the appropriate times can lead to inaccurate attitude readings, which could be detrimental during flight operations.

The other options describe situations that do not specifically address the need to cage the indicator to prevent errors directly associated with power transitions. While they may be relevant in a broader flight safety context, they do not highlight the critical response necessary to ensure that the standby attitude indicator functions correctly during electrical power changes.