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Qantas pilots didn’t wear oxygen masks despite fumes, says ATSB

written by Staff reporter | April 16, 2024

Rob Finlayson shot this QantasLink 717, VH-NXO.

Two QantasLink pilots who experienced hypoxia-like symptoms on a flight from Sydney to Hobart last year did not use supplemental oxygen, the ATSB says.

Flight QF1541, operated by National Jet Systems for QantasLink, was approaching Hobart on board the Boeing 717 VH-NXM (similar aircraft pictured) on 6 June, 2023, when the pilots smelled a “chlorine odour” from the air vents. The captain, subsequently feeling unwell, turned over control to the first officer.

The ATSB’s final report notes that the odour had been previously detected in the forward galley as the plane was climbing out of Sydney, causing similar symptoms in two cabin crew members, but had not been detected by the flight crew in the cockpit.

Prior to touching down, the first officer noticed their reaction to an aircraft deviation was slowed, and they started to feel “hazy”.

Due to the impending landing, and perceived difficulties of donning the mask, supplemental oxygen was considered but not used, according to the report from the ATSB investigation into the incident details. A go-around was also considered but rejected following an assessment that continuing the landing was the safest course of action.


After landing and shutting down the aircraft, both pilots reported persistent headaches, and they were assessed by a company doctor via teleconference, during which the doctor observed that the captain’s speech was noticeably affected, consistent with impairment. The captain then attended hospital for further testing.

The captain later described the symptoms as fogginess of thought, confusion, deteriorating situational awareness, weakness and tingling in the arms and legs, and narrowing of vision.

“This incident is a reminder to pilots to be alert to the potential hazard posed by odours and fumes, and to not hesitate to use supplemental oxygen,” said ATSB chief commissioner Angus Mitchell.

“The use of oxygen is a proven mitigating action in the case of environmental hazards and its rapid use ensures flight crews’ physical and mental capacity is maintained.”

VH-NXM had seen two other cabin air quality (CAQ) issues in the six days prior to the incident flight, including a “rotten garbage smell” on 1 June and a similar chlorine smell on 4 June, forcing the plane to redirect to Sydney.

The ATSB investigation also identified that while the cabin air quality events procedure had been conducted earlier in the flight after cabin crew reported a chlorine odour and symptoms during the climb out of Sydney, this procedure did not consider the possible application of the smoke/fumes procedure or the incapacitation procedure.

“This increased the risk of flight crew being adversely affected by such an event during a critical stage of flight,” noted Mitchell.

Shortly after the incident, National Jet Systems issued a notice reminding flight crews to consider supplemental oxygen use and the declaration of a PAN in response to a cabin air quality event.

Then, in March 2024, the operator advised the ATSB of a number of additional safety actions, including training updates, a review of checklists, and the incorporation of learnings into the newly-introduced A220 aircraft’s smoke/fumes, hypoxia and incapacitation procedures.

“Airborne contaminants may result in the rapid onset of incapacitation, which although possibly subtle, can significantly affect the safety of flight,” said Mitchell.

“Physical or cognitive incapacitation can occur for many reasons and may be difficult for others, or even the sufferer, to detect and respond to.

“As such, pilots should not hesitate to use supplemental oxygen.”

In a statement, Qantas Group chief medical officer Dr Ian Hosegood reinforced the “critical” importance of using oxygen masks in rare cabin air quality events such as this.

“Since this incident occurred, Boeing 717 pilot training and manuals have been updated to ensure pilots are clear on when they should use oxygen masks and we have updated our maintenance program to reduce the risk of similar cabin air quality incidents,” he said.

“We also conducted a review across other Qantas, Jetstar and our other regional operations and found that manuals and training correctly directed when pilots should don an oxygen mask.”

VH-NXM experienced no other cabin air quality issues following the incident and was retired in September 2023.

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