2012 Boeing 757 Cabin Airflow Incident

Incident Overview and Aircraft Details On July 18, 2012, a Boeing 757-223 operated by an Icelandic airline experienced a disturbance during a passenger flight from Reykjavik-Keflavik to Frankfurt/Main. The aircraft, manufactured in 1992 with serial number 25295, was powered by Rolls-Royce RB211-535E4B engines. The flight carried seven crew members and 132 passengers. No personal, material, or third-party damage was reported, and the incident was classified as a disturbance rather than a serious incident because all crew members completed their duties. ## Flight Progression and Crew Symptoms Approximately one hour after takeoff, while cruising at Flight Level 390, the Purser informed the Pilot-in-Command that most cabin crew members were experiencing headaches, dizziness, and sweating during service. The pilots initially shut off the right recirculation fan to increase fresh air supply. After consulting with the airline's Maintenance Control Centre, the fan was restarted, and the aircraft descended to Flight Level 350 and then Flight Level 310 to reduce the cabin pressure altitude from 7,000 ft to approximately 4,000 ft. Cockpit indicators for cabin pressure, air conditioning, and other systems showed no abnormalities. The crew reported feeling better after using oxygen in the cockpit and galley areas. During the descent to Frankfurt, when the aircraft briefly leveled off at Flight Level 200 and engine power was increased, the cabin crew reported severe dizziness, headaches, blue lips and fingers, and numbness in their legs. The Pilot-in-Command requested priority for the approach. Later, the PIC and three flight attendants simultaneously experienced dizziness for 1-2 seconds in the forward galley area. The aircraft landed in Frankfurt at 12:55 local time without further issues. ## Investigation Findings and Conclusions The Cockpit Voice Recorder (CVR) confirmed that crew members promptly reported their symptoms to the pilots. The BFU concluded that the documented immediate reporting and consistent symptom descriptions indicated problems with cabin air during the flight. Symptoms such as blue lips and dizziness suggested oxygen deficiency in the affected individuals. While all seven cabin crew members were affected, the pilots and passengers were not, possibly due to the higher oxygen demand of moving crew members compared to seated passengers. Post-landing medical examinations of the crew yielded no abnormalities, and passengers did not seek medical help. Maintenance tests of the air conditioning and cabin pressure controllers found no issues, and engine tests showed no signs of smoke or oil. However, the right air conditioning pack could not be set to high flow. Boeing noted that similar issues on other 757s had been attributed to restricted airflow in the cabin, particularly in the rear, caused by foreign objects in the air conditioning system. The BFU concluded that the health impairments experienced by the flight attendants during cruise were probably caused by oxygen deficiency.