During what condition is the emergency oxygen system triggered?

The emergency oxygen system is specifically designed to activate automatically during critical situations in the aircraft. When an ejection occurs, the pilot faces an immediate need for supplemental oxygen due to the rapid change in altitude and potential exposure to low atmospheric pressure, which can cause hypoxia. The system provides a quick source of oxygen, ensuring the safety and survival of the pilot during this emergency scenario.

While low oxygen pressure can indeed trigger the need for supplemental oxygen, this condition is not the sole reason for the emergency oxygen system's activation, as it is intended for more extreme circumstances like ejection. Similarly, when the aircraft is on the ground or during normal flight operations, the need for emergency oxygen is not as immediate, as the cabin pressure is usually managed effectively and pilots have access to regular oxygen systems.