What setting do you select on a pressure-demand oxygen regulator in case of smoke in the cockpit?

In the event of smoke in the cockpit, selecting a setting of one hundred percent on a pressure-demand oxygen regulator is crucial for ensuring the safety of the flight crew. This setting delivers pure oxygen directly to the user without mixing it with ambient air, which is critical when smoke is present.

The rationale behind this is that smoke can contain harmful gases and particulate matter that may interfere with normal breathing. By using one hundred percent oxygen, crew members can avoid inhaling these harmful substances. The pure oxygen provides adequate respiration support and minimizes the risk of hypoxia, ensuring a clear mind to manage the situation effectively.

This setting is specifically designed for emergencies where the air quality is compromised, positioning the crew to maintain physiological and cognitive function in a challenging environment.