When is liquid oxygen (LOX) considered full?

Liquid oxygen (LOX) is considered full when the gauge reads at 95%. This is due to the properties of LOX and the importance of accounting for the thermal contraction and liquid expansion that occurs with temperature variations. A gauge reading of 95% ensures there is enough margin to accommodate any changes in pressure or temperature that may occur during operation, which helps avoid potential issues such as oxygen starvation during flight.

In contrast, gauges reading lower than 95% could suggest less than optimal performance or inadequate supply during mission-critical times. For example, a reading at 90% may not provide sufficient reserve, potentially leading to an insufficient oxygen supply for the crew due to environmental factors. Therefore, maintaining LOX at or above 95% is crucial for safety and operational effectiveness within aviation standards.