What happened
On January 28, 2007, a BAe 146-300 was operating a series of flights involving Frankfurt and Bremen. During the initial ground period in Frankfurt, the crew started the Auxiliary Power Unit (APU) and activated the two air conditioning packs using APU air. At this time, the captain noticed an indefinable odor, which dissipated immediately after Pack 1 was switched off. During the subsequent flight from Frankfurt to Bremen, the crew noted a 60 °C temperature guide temperature (TGT) differential during bleed air sharing between engines 1 and 2.
On the return leg from Bremen to Frankfurt, the odor recurred during the approach while both packs were supplied by engine air. The smell vanished once Pack 1, supplied by engines 1 and 2, was deactivated. As the aircraft crossed the runway threshold, the captain felt a sense of malaise, though he could not immediately identify the cause. Upon arrival at the parking position and after passengers had disembarked, the captain realized he was suffering from severe symptoms, including fatigue, confusion, headaches, and intense eye irritation. He also experienced significant difficulty concentrating on necessary flight calculations. The co-pilot, who was acting as the pilot flying, remained asymptomatic and did not notice any unusual odor.
The investigation
The BFU investigated the incident to determine the cause of the air quality issues and the pilot's physical impairment. The investigation included a review of the airline's error analysis, which had failed to find a cause for the air conditioning contamination. During engine test runs at various power settings and acceleration rates, no oil odor was detected. Medical examinations conducted on the captain following the event provided no clinical evidence to explain the cause of his impairment.
Findings
- The captain experienced cognitive and physical impairment characterized by confusion, fatigue, and headaches.
- An unidentified odor was present in the cockpit during both the initial ground operations and the final approach.
- The airline had been conducting an air quality modification campaign since December 2006 to address known issues with odors in the BAe 146 fleet.
- Previous investigations by international authorities into similar odor incidents in this aircraft type have not established a definitive link between air contamination and physiological symptoms.