国航一航班客舱氧气面罩系统出现故障返航，已安全落地首都机场

Group 1 - The core incident involves a malfunction of the cabin oxygen mask system on China International Airlines flight CA965 from Beijing to Frankfurt, prompting a safe return to Beijing Capital International Airport [1] - The aircraft's cabin pressure and other systems were reported to be functioning normally during the incident [1] - The airline has arranged for another aircraft to handle subsequent flight operations following the incident [1]