Insufficient quantities of passenger and/or flight crew oxygen being carried for routes transiting high terrain.

Aircraft are required to carry sufficient flight crew and passenger oxygen in the event of a cabin depressurisation for the aircraft to descend to reach a safe altitude. For an aircraft transiting mountainous terrain, the amount of time to descent to a safe altitude is increased and therefore proportional quantity of crew as well as passenger oxygen is required.

Carrying the incorrect quantity of oxygen may result in flight crew and passenger incapacitation/hypoxia in the event of a depressurisation.