Which characteristic applies to on-board oxygen generating systems (OBOGS)?

On-board oxygen generating systems (OBOGS) are designed to provide a continuous supply of oxygen to pilots and crew during flight, particularly at high altitudes where ambient oxygen levels are insufficient. The important characteristic of OBOGS is that it can produce oxygen as required, which means it does not have a fixed capacity or a set duration limitation on how long oxygen can be supplied during a flight, hence it is considered to have unlimited oxygen duration.

This capability allows pilots to have sufficient oxygen available for the entire duration of the mission, which is critical for maintaining cognitive and physical performance under high-altitude conditions. As such, the design and function of OBOGS optimize safety and operational efficiency in aviation environments, differentiating it from traditional oxygen sources that rely on pre-stored supplies.