Pilots seriously affected by cabin air quality while preparing to land

Two pilots were dangerously affected by a cabin air quality incident on a QantasLink Boeing 717-200 flights as it prepare to land at Hobart airport in Australia last year.

The Australian Transport Safety Bureau published their report into the incident yesterday and  National Jet Systems – who own the QantasLink brand – have announced changes to their training procedures as a result of the incident. 

When the flight set of from Sydney on 6th June 2023, two members of the flight crew experienced a strong chlorine smell in the area of the front galley. They experience symptoms of dizziness, a feeling of pressure in the head and a metallic taste in the mouth. The odour quickly dissipated and no-one else among the crew or the passengers reported smelling it.  

The two crew members soon declared themselves fit to continue the flight, so the plane carried on to Hobart.

The following is verbatim from the ATSB report:

At about 2108, about 10 NM from Hobart Airport and at an altitude of about 4,000 ft, the captain noticed a chlorine odour, which they assessed as coming from the flight deck air‑conditioning gasper vents. The first officer noticed the odour shortly after the captain but neither the captain nor first officer experienced any effects at this time. The captain and first officer reported that the odour was transient and disappeared after about 10 seconds.

About 30 seconds later, while the flight crew were configuring the aircraft for landing on runway 30, the captain noticed quickly developing adverse effects on vision, mental capacity, and movement, and self-assessed as unable to safely fly the aircraft. 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. The captain indicated their intention to transfer control of the aircraft to the first officer by stating ’your controls’. At that time the first officer noticed that the captain looked pale but did not appear incapacitated.

When about 8.5 NM from the runway at an altitude of about 3,250 ft, the first officer took over the role of PF [Pilot Flying]. At the same time, the captain communicated that they were able to continue as PM [Pilot Monitoring] with the assistance of the first officer. The first officer noted that the captain correctly actioned the commands to lower the flaps and landing gear to configure the aircraft for landing. The first officer was not experiencing negative symptoms at that stage and, as the odour was not detectable, assessed that emergency oxygen was not required.

Shortly after, the first officer noticed that the captain was struggling to read the checklist and was tripping over words, but managed to self-correct and read back air traffic control calls correctly. The first officer visually monitored the captain’s condition and ensured that no inadvertent contact was made with the flight controls.

At about 3 NM from the runway and an altitude of 1,000 ft, the first officer noted that the captain, as PM, had not made the required ‘stable’ call to confirm the aircraft was stabilised on the approach. The first officer prompted the captain with a call of ‘1,000 feet’, and the captain responded with ‘stable’. The first officer confirmed that the aircraft was stable and continued the approach. The first officer considered making a PAN call [An internationally recognised radio call announcing an urgency condition which concerns the safety of an aircraft or its occupants but where the flight crew does not require immediate assistance], but assessed it was unnecessary due to the immediacy of landing.

At about 100 ft above the runway elevation, the first officer experienced difficulties keeping the aircraft lined up with the runway centreline. The first officer reported that the aircraft was drifting to the right of the centreline, and that their reactions to correct the drift were slower than normal. The first officer also reported feeling ‘hazy’, however these difficulties were not communicated to the captain at that time.

At about 21:13, the aircraft landed at Hobart Airport and was taxied to a parking bay. The flight crew was assessed by a company medical doctor via teleconference, during which the doctor observed that the captain’s speech was noticeably affected, consistent with impairment. This resulted in the captain attending hospital for further testing.

The two forward cabin crew later reported the same smell on landing and again both felt similar mild symptoms. The first officer also reported a dull headache post‑flight, which lasted about two days.

Subsequent tests showed that the pilot had slightly elevated levels of CO2 in his blood, although within an hour this had fallen to normal levels. 

A week earlier on 1st June, cabin crew had reported a rotten garbage smell after take-off, lasting five minutes. Maintenance was carried out in an attempt to remedy the issue.

Three days later, on 4th June, a chlorine smell was reported at the forward and aft galleys as well as the flight deck during take-off for between three and five minutes. Cabin crew reported mild symptoms of dizziness and shaking and the flight was diverted to Sydney. Systems were subsequently inspected for signs of oil leaks and functional checks were carried out but no odours could be detected on the ground.

The aircraft made four further flights without air quality issues before the day in question. The resultant, intensive checks once again failed to identify the source of the chlorine smell.

In response to the incident, National Jet Systems issued a Safety Action Notice reminding their flight crews to consider using supplemental oxygen and the declaration of a PAN in response to a cabin air quality event. They also advised the ATSB they had taken the following safety actions:

• The flight crew recurrent simulator training syllabus had been updated to include in‑seat instruction specific to pilot incapacitation, followed by a practical exercise donning oxygen masks and conducting an approach, landing, and taxiing to the gate while using oxygen.
• A review of smoke/fumes checklist and simulator training was undertaken.
• Learnings from this occurrence have been incorporated into the newly‑introduced company A220 aircraft smoke/fumes, hypoxia, and incapacitation procedures.
• A review of hypoxia training material to include specific reference to histotoxic hypoxia was undertaken, with draft content awaiting input from the Qantas chief medical officer.
• Aircrew emergency procedures documentation and training pertaining to the recognition and management of crew incapacitation have been updated to include subtle and cognitive incapacitation.