Icelandair B752 enroute on Jul 18th 2012, all cabin crew increasingly feeling sick

Last Update: September 3, 2013 / 18:18:49 GMT/Zulu time

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Incident Facts

Date of incident
Jul 18, 2012

Classification
Accident

Airline
Icelandair

Aircraft Registration
TF-ISL

Aircraft Type
Boeing 757-200

ICAO Type Designator
B752

Germany's BFU released their final report concluding the probable cause was:

During cruise flight the cabin crew members suffered health problems probably caused by lack of oxygen.

The BFU reported that in cruise flight at FL390 about one hour into the flight most of the cabin crew members experienced dizziness, headaches and sweating while attempting to provide meal service to the passengers. The purses instantly went to inform the captain, who in response switched the right hand re-circulation fan off in order to improve oxygen supply to the cabin. The captain subsequently discussed the issue with dispatch, as result the re-circulation fan was turned on again and the aircraft descended from FL390 to FL350 and FL310 permitting to reduce the cabin altitude from 7000 to 4000 feet. Cockpit indications of the airconditioning systems remained normal throughout the flight. The cabin crew members were provided with oxygen in the cockpit or the galley area and felt much better. The captain therefore decided to continue the flight to Frankfurt.

While descending towards Frankfurt the aircraft needed to level off at FL200 causing the engine thrust to be increased, almost immediately the health condition of the cabin crew worsened, besides headache, dizziness the flight attendants now showed blue lips and fingers as well as numbness in the legs. The cockpit was promptly informed again. The captain disengaged the right hand air conditioning system and right hand re-circulation fan and requested a priority landing into Frankfurt.

The captain took a lavatory break shortly afterwards and took the opportunity to talk to the three flight attendants in the forward galley. During that discussion all four, including the captain, experienced dizziness for about 1-2 seconds. The captain returned to the cockpit and no longer experienced any symptoms.

Following safe landing the captain talked to the BFU and was instructed to seek medical treatment for himself and his cabin crew and to have blood tests done. No anomalies were found in the medical examination and blood tests.

Examination of the cabin air as well as air filters after landing also did not find anything. Examination of the air conditioning systems did not reveal anything out of the ordinary.

The BFU reported: "The aircraft manufacturer Boeing said to the operator one day after the incident that in the past similar problems had occurred in airplanes of the same type which were attributed to restricted airflow in the cabin in particular in the aft part of the cabin. In those cases the restricted airflow had been caused by foreign objects in the air conditioning system."

The BFU analyzed:

The CVR recordings of the conversation between the purser and the pilots show that the cabin crew members promptly informed the pilots about their health problems. The reasons being the intensity of the felt problems and that all cabin crew members were affected. It cannot be excluded that similar occurrences have happened in the past and, therefore, played a part here. The BFU is of the opinion that both, the documented prompt report to the pilots and the fact that several persons unanimously described the symptoms, indicates that there was a problem with the cabin air during the flight.

The cabin crew members described symptoms such as blue lips and dizziness which could indicate a lack of oxygen. Even though all seven cabin crew members (editorial note: the BFU reported a total of 7 crew members including the pilots) were affected, neither the two pilots in the cockpit nor the passengers had any adverse effects. One possible explanation could be the increased oxygen demand of the cabin crew due to them moving around the cabin whereas passengers and flight crew were seated.