British Aerospace Plc BAe 146-100, VH-NJD

The crew carried out the take-off in the British Aerospace Plc BAe 146 (BAe 146) with number 4 engine air bleed selected on, and engine numbers 1, 2 and 3 and the auxiliary power unit air bleeds selected off in compliance with an item in the discrepancy log. Shortly after take-off, at approximately 700 ft above ground level, the copilot switched on the remaining engine air bleeds and both air conditioning packs. Shortly after selecting engine anti-ice on, the pilot in command (PIC) asked the copilot if he could smell fumes. The copilot agreed that he too had detected a smell. The engine anti-ice system was then switched off.

A short time after commencing the cabin service, a flight attendant (FA) called the flight deck and informed the PIC of fumes in the cabin and that they were particularly bad near the rear of the cabin where another FA had donned an oxygen mask. This mask was of the diluter type that supplies a mixture of the incoming oxygen with the ambient air that is then delivered to the user. The copilot then indicated to the PIC that `he felt he should go onto oxygen' and donned an oxygen mask, but the PIC did not feel he needed to perform the same action at that time.

The PIC later stated that he did not don his oxygen mask at this time, as he was considering if the fumes were oil related in accordance with a notice to pilots (NOTOP) from the operator. This NOTOP required the PIC to make a diagnosis as to the source of contamination `wherever it is safe and practicable to do so'. The PIC's findings were required by the operator to determine the level of response required to later rectify the problem and return the aircraft to service.

The PIC stated that the aircraft type had a history of fumes related problems and not donning his oxygen mask was a normal practice for himself and, he believed other aircrew employed by the operator. He said `most smells and odours were considered the normal environment of the day to day operation of the BAe 146' and he would have discontinued his NOTOP diagnostic action if he perceived a flight hazard issue and would have reverted to the emergency checklist action. He also stated that the copilot, being on oxygen, could confirm a successful isolation procedure by occasionally removing his mask and comparing pure air with the ambient air of the flight deck.

This was at variance with the emergency checklist for SMOKE/FUMES/FIRE IN COCKPIT/CABIN. This list takes priority over any other action. The first item on the checklist is `Oxgen masks and goggles...Flight crew don, check 100%'. The imperative in relation to fumes events was also highlighted in an all operator message (AOM) from the manufacturer, which states in part `pending the definition of any necessary corrective actions, oil leaks and cabin/flight deck smells must be regarded as a potential threat to flight safety and not just a nuisance'.

The copilot completed fault isolation checks that appeared to improve the air quality on the flight deck. The PIC then asked the FAs if they could come to the flight deck so that he could better assess the situation in the cabin. The FAs came forward in turn, opened the flight deck door and entered. This action was at variance with the operations manual actions for flight attendants in the event of smoke/fumes in the cabin. The manual stated that, in the event of smoke/fumes, the FAs were to inform the PIC via the intercom and were not to open the flight deck door.

In his original report, the PIC stated that `each time when they opened the flight deck door, we noticed that the odour intensified'. The FAs' cabin crew reports to the operator also stated that the odour and fumes were still evident in the passenger cabin during the remainder of the flight. The PIC described the odour to be unlike any odour previously encountered and then decided the safest option was to return to the departure airport.

The incident operating crew underwent medical examinations that evening as directed by the operator after the event. The PIC stated that the medical practitioner they visited told him she knew very little about the effects of odours on crew and was unaware of any specific blood testing requirements for such an event. Medical testing information printed by the aircraft manufacturer in Service Information Letter (SIL) 21/45 Issue Number 1, dated January 2001, details specific test requirements. The PIC stated that it was sometimes difficult to find a medical practitioner at short notice (especially late at night) who was familiar with the required testing procedures.

After advising the medical practitioner that he was unsure if he would be able to work the following day, the PIC was given a medical certificate excusing him from flight duties for the following 24 hours. Even though he donned his oxygen mask, the copilot was similarly affected and was also excused from flight duties for the same period as the PIC. The operator reported that the remaining crew did not exhibit any residual effects from the incident.

A maintenance investigation by the operator included compliance with the latest airworthiness directive and service bulletins. All engines and the auxiliary power unit were checked. The airconditioning regenerative ducting and the delivery ducting to the rear cabin were also dismantled and inspected. That investigation determined that the number-3 engine was the likely source of the fumes and the engine was changed. The aircraft was returned to service with subsequent operating crews reporting no further fumes problems.

The aircraft type has been the subject of recurring fume incidents throughout its operating life as commented on by the PIC. It has been subject to intense investigations by both operators and the manufacturer. These investigations have resulted in the promulgation of several service information letters, bulletins, airworthiness directives and NOTOP troubleshooting requirements.

Because of this history, the fume events may have become `routine' in the thinking of some operating crew and awareness of the possible risks may have diminished as a result. This familiarity was a concern to the manufacturer as evidenced by the wording in the AOM to the operator. Familiarity may have led the PIC to delay the donning of his oxygen mask. The imperative to ascertain the source of contamination as soon as practicable in accordance with the operator's NOTOP directive may have also influenced the PIC's decision making.

Although the PIC felt that there was no need for him to don his oxygen mask, this action was contrary to the operator's emergency procedures. The completion of the NOTOP diagnostic action should be accomplished after any emergency checklist actions. By choosing to remain exposed to potentially contaminated air, the PIC might have risked degradation of his faculties, which then may have reduced his ability to correctly determine if there was a flight hazard and respond appropriately. This increased exposure may also have long term or cumulative effects that are not yet understood.

If the emergency checklist had been performed first, both pilots should have donned oxygen masks and the subsequent occasional removal of an oxygen mask by one pilot for air sampling would have likely had minimal safety consequences. This is further reinforced by the fact that both pilots experienced some after-effects that required stand down from flight duties even though one, the copilot, had donned an oxygen mask early in the event.

The PIC's request to the FAs and their subsequent actions in opening the flight deck door were contrary to procedures. The smoke/fumes procedures in both cockpit and cabin are safety of flight defences designed to minimise the potential for flight crew incapacitation by isolating the flight deck from cabin hazards. Again the possible perception that fume events are a `routine' part of the environment in which the crews operate may have led both flight and cabin crew to believe that the action was appropriate under the circumstances.

The oxygen bottle used by the cabin crew was fitted with a diluter or therapeutic type mask. This design does not provide protection from smoke or fumes as most of the air mixture provided is ambient air. Under certain circumstances involving heavy contamination by fumes, the use of this type of mask might mislead the user into a false sense of protection and lead to the possibility of being overcome by the fumes. The limited protection afforded by this type of mask should be brought to the attention of cabin crew.

Local safety action

The operator has undertaken to raise awareness among flight crew about the risks of possible crew incapacitation from fumes and the importance of not delaying the donning of oxygen masks during emergency checklist actions. This notice should include reiteration of the primacy of any immediate recall emergency checklist actions over other operator documentation. This will be achieved by a re-write of the procedures detailed in the operator OM-2 operations manual.

The ATSB expressed concern to the operator about the lack of advice provided to medical staff as to what medical tests should be carried out on crew after possible exposure to fumes. The operator undertook to introduce a procedure to communicate a list of prescribed minimum tests, published by the airframe manufacturer in SIL 21/45, to medical practitioners whenever crewmembers require testing for fume exposure. This would ensure that the attending doctor would have the latest testing information available at the time of the test. It was agreed that the information should, as a minimum, cover the appropriate medical tests for such exposure as listed on Pages 10 and 11 of BAe SIL 21/45 Issue Number 1 dated January 2001 (or as amended).

With regard to the concern about appropriate use of the diluter type masks and portable oxygen bottles by cabin crew in heavy smoke or fumes situations, the operator has undertaken to issue a flight attendant safety memo (FASM). This FASM will raise awareness among cabin crew of the limitations of the portable oxygen bottle and diluter type masks when used in a fumes contaminated environment.