How many feet are added to cabin altitude to readjust for a High Alt mode caution light?

When dealing with a High Altitude mode caution light, an adjustment must be made to ensure that the aircraft's cabin altitude remains within safe operational parameters. The correct adjustment is to add 650 feet to the current cabin altitude. This additional altitude accounts for the potential discrepancy between the actual cabin environment and what might be indicated due to the caution light activation.

This adjustment is critical because it helps maintain passenger safety by ensuring that the cabin pressure remains adequate and is not approaching dangerous levels that could lead to hypoxia or other cabin pressure-related issues. Following the proper adjustment protocols is essential for pilots and crew to manage cabin pressurization effectively during flight operations.

The other options do not reflect the appropriate safety adjustments needed in response to the High Alt mode caution, as they either fall short or exceed the necessary safety threshold.