The crash site of the twin turboprop Gulfstream 695A, that crashed near Cloncurry, killing the pilot and two camera operators on board.(Supplied: ATSB)
Blue lips, slurred speech, euphoria, confusion — these are just some of the warning signs of hypoxia, a lack of oxygen in the body, which can be deadly in the air.
It's rare, but hypoxia has been behind several fatal plane crashes in Australia.
The Australian Transport Safety Bureau (ATSB), which investigates aircraft incidents, recently found thata 2023 triple-fatal crash near Cloncurry was "entirely preventable"and that the pilot likely suffered hypoxia caused by a well-known, long-standing defect.
Respiratory specialist Dr Ian Yang says, put simply, it's low oxygen in the body and brain.
Dr Yang says common symptoms include confusion, rapid breathing, a racing heart and a false sense of calm.
"A lot of our patients living with moderate to severe conditions like COPD (lung disease) will have low oxygen but it's very rare in the general community," he says.
"If someone comes to us with moderate to severe lung conditions we test in our laboratory to test what their oxygen levels are, if it drops too low we'll recommend they need oxygen on the plane."
Hypoxia can start around 10,000 feet if cabin pressure drops and oxygen systems fail.(Flickr: David Spinks)
Aviation doctor and pilot Dr Hui Tan says hypoxia can start silently above 10,000 feet, if cabin pressure drops and oxygen systems fail.
"Pilots might feel fine, then suddenly can't function," he says.
Dr Tan says some have reported tingling ears, nausea, or warmth before losing awareness.
The ATSB has investigated seven major hypoxia-related incidents since the late 90s, from a 2000 crash that killed all onboard, to a 2020 case where a pilot passed out mid-flight.
In many cases, pressure systems failed or oxygen masks weren't working.
Some pilots, particularly those in the military, undergo hypoxia simulation training to learn to spot the symptoms early.(Supplied: Flying Whales)
Yes, with training and awareness.
Some pilots, particularly those in the military, undergo hypoxia simulation training to learn to spot the symptoms early.
Dr Tan operates a specialised hypoxia chamber in Western Australia to help pilots experience and recognise the signs of low oxygen in a safe way. He himself has experienced it first-hand.
"I was quite taken aback by the symptoms, it was similar to being under the influence where you have the light-headedness and I was convinced if I experienced that again in an aircraft I'd know what those symptoms were and I could do something about it," he says.
Dr Tan helps pilots recognise the signs of hypoxia by simulating it in a hypoxia enclosure.
"That's why we offer the training we do, so pilots can experience these symptoms first-hand in our enclosure and, if something happens in future, recognise the same hypoxia symptoms and put their oxygen mask on before they start troubleshooting.
"Where people get in trouble is where they don't recognise the symptoms.
"I set this up to give pilots awareness and if I save one life from hypoxia then this training has been worth it."
In-flight? Immediate oxygen and descent.
Air traffic controllers are also trained to spot signs including slurred pilot speech and can direct aircraft to descend quickly to safer altitudes.
Dr Yang says on the ground, treatment depends on the cause, but in aviation, it is all about quick recognition and fast action.
A plane crash that killed three people in outback Queensland was "entirely preventable" and was caused by a well-known, long-standing defect.
"The treatment for those with underlying conditions like COPD can include inhalers or exercise, and in serious cases oxygen," he says.
"In aviation the treatment for patients with low oxygen is oxygen on the plane."
The fatal 2023 crash is subject to an open coronial investigation.
In a statement, a CASA spokesperson says the Cloncurry incident highlights the importance of being aware of the risk of hypoxia.
"We note the ATSB’s report and are considering the findings," the spokesperson says.
Topic:Transport Accidents and Incidents
Topic:Defence and National Security