During normal operation, how should the oxygen regulator levers be positioned?

The correct positioning of the oxygen regulator levers during normal operation is critical for ensuring adequate oxygen supply and safety for the crew. In this scenario, having the SUPPLY lever set to ON ensures that oxygen is being delivered to the system. The DILUTER lever set to 100% allows for the highest concentration of oxygen to be supplied, which is particularly important during operations at high altitudes or in situations where supplemental oxygen is necessary. Setting the EMERGENCY lever to Normal indicates that the oxygen system is in a standard operational mode while allowing for quick access to emergency oxygen if needed.

Overall, this configuration provides a balance of sufficient oxygen concentration and readiness for any potential emergency, aligning with safety practices and operational procedures in aviation. This setup ensures that the crew can effectively manage their oxygen levels during various phases of flight, especially under conditions where oxygen supplementation becomes necessary.