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As Sydney airport heaved during the holiday period, air traffic controllers were facing an unusually fetid issue – the raw smell of sewage was overpowering the control deck.
Almost 6 million passengers passed through the airport between Christmas and New Year’s in 2024, the busiest season for international travel on record.
Sydney airport air traffic control, where the raw smell of sewage was overpowering the control deck.Credit: Artwork: Marija Ercegovac
Air traffic controllers were dry heaving at their desks.
An incident log from Air Services Australia, obtained under a freedom of information request, reveals the first complaint on December 17, 2024.
“Foul smell entering tower cabin environment. Smell is particularly evident when local winds are from the North East.”
The gases from Sydney’s sewer system were escaping directly into the control tower.
Sydney Airport was heaving during the holiday period.Credit: Louie Douvis
The waste of 1.8 million residents across Sydney, from Campbelltown to Fairfield and Concord, is sent to the Malabar Sewage Treatment System, which passes through the airport on the way from Arncliffe to Malabar.
“Employees are heavily affected by sewer odour concerns to the point of feeling sick,” read the entry in a Sydney Water system.
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“Smell emanating from Sydney Water Odour Control Unit (OCU),” an Air Traffic Controller wrote in an incident report.
“Conversations with Sydney Water indicate that the smell detected is excess hydrogen sulphide.
“The rate the OCU is outputting H2S is in excess of 5PPM. The safe levels of exposure are in the realm of 1PPM.
“A Google of the effects of H2S is quite alarming particularly given that staff are exposed to the smell often for the duration of the shift.”
The Safe Work Australia exposure standards limit the maximum eight-hour exposure average to 10 parts per million (PPM). A concentration of 5PPM can irritate the eyes nose and throat, with possible headaches, dizziness, and nausea.
“It is reasonable to suggest that any and all staff working through December 2024 have been exposed to this smell,” the air traffic controller wrote.
Almost 6 million passengers passed through the airport between Christmas and New Year’s in 2024.Credit: AP
Sydney Water technicians inspected the sewer. Everything was operating fine downstream of the airport.
As the issue continued, staff in the control deck contacted Sydney Water again on January 7, 2025.
“Sydney Water was advised all controllers get nauseous and sick heaving over the odour,” the updated log reads.
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The water corporation’s lead engineer was now investigating, and told airport staff they believed the system may have been overloaded after a fire at another facility. An odour control unit at Padstow was offline after the fire earlier in December.
A filter at the airport was also clogged, potentially after having to deal with the extra load. The filter had been due for routine replacement, which was delayed due to issues with the supplier of activated carbon.
Sydney Water took action. The airport odour control unit was switched off, and a replacement filter was rushed in.
“Sydney Water has thoroughly investigated and addressed two separate incidents at its facilities in Padstow and Mascot and found no strong evidence of correlation,” a spokesperson said.
“The odour issue was found to be caused by an activated carbon filter reaching the end of its effective treatment capacity. This was promptly addressed by replacing the filter on January 10, 2025.
“No further odours have been reported at the facility since the replacement.”
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