The co-pilot reported that during the BAe 146 handover, the
previous crew stated that the aircraft had an air-conditioning
contamination problem and that it appeared to emanate from the No.
2 air-conditioning pack. On entering the aircraft the co-pilot
noted that only the No. 2 pack was operating and the ambient air
was contaminated. The crew switched off the No. 2 pack until the
engines were started and the aircraft had taxiied to the runway
holding point.
After take-off, the co-pilot reported that he began to feel
nauseous and had developed a headache. After discussing the problem
with the aircraft captain, he donned an oxygen mask and gradually
felt better. During the flight, a flight attendant entered the
cockpit and reported a soreness of the head, and that she felt
nauseous.
On the return flight, the crew left the No. 2 pack switched off.
They reported that the contamination was far less noticeable than
the previous flight.
Inspection by the company maintenance personnel did not
initially find any evidence of contamination. However, the co-pilot
reported that subsequent replacement of the aircraft auxiliary
power unit appeared to have rectified the air contamination
problem.