Which statement is true regarding the activation of the emergency oxygen cylinder during OBOGS failure?

The statement that the emergency oxygen cylinder does not activate automatically is correct because the system is designed to require manual activation by the pilot in the event of an On-Board Oxygen Generating System (OBOGS) failure. This manual activation ensures that the pilot has control over when to deploy supplemental oxygen, rather than it activating automatically under all circumstances.

In the case of an OBOGS failure, pilots are trained to recognize the indications of an oxygen system malfunction and to take the appropriate steps to manually activate the emergency oxygen system to ensure they receive the necessary oxygen. This design prioritizes pilot awareness and response in critical situations, rather than relying on an automatic system that could potentially activate inappropriately or at the wrong time.

The other options imply automatic or conditional activation, which does not reflect the operational procedures of the T-6B aircraft's emergency oxygen system. This clarity adds to the understanding of how pilots should respond in different scenarios related to oxygen system failures.