times sudden loss pressure airliner cabin occurred ryanair flight frightening potentially painful experience passengers usually endanger aircraft half dozen episodes rapid pressure loss suffered airliners past year pilots follow standard procedure cabin pressure suddenly drops cruising altitude oxygen masks constantly shoulder put aircraft emergency descent sea level altitude air becomes comfortably breathable time crew would declared emergency route air traffic control requested immediate clearance lower altitude landing nearby airport meantime oxygen masks deployed automatically supply passengers crew descent ryanair boeing performed exactly procedure suffered pressure loss pilots descended five minutes according authorities limoges airport landed media passengers may call manoeuvres plunge free fall descent rate per minute perfectly controlled within normal performance aircraft assuming flight systems functioning