Local aviation authorities are investigating two “serious incidents” of Cathay Pacific pilots suddenly — and, as yet, inexplicably — losing their vision during flights to Hong Kong, with both cases taking place within less than a month of each other earlier this year.
The incidents — disclosed in two preliminary reports by the Hong Kong Air Accident Investigation Authority (AAIA) yesterday — took place on a Cathay flight to Hong Kong from Hokkaido, Japan, in late January, and on another from Perth, Australia in late February. Both flights landed safely.
The January flight from Hokkaido was somewhere near Taipei when “the Captain experienced a sudden loss of visual acuity, the situation lasted for about 30 minutes,” the AAIA report reads.
The captain informed the first officer of the loss of vision and relinquished the controls, pushing his seat back and strapping on the seat’s shoulder harnesses “to prevent any possible interruption with the operation of the aircraft.”
As the flight approached Hong Kong, the first officer requested a priority landing, and the plane was met by paramedics. The captain remained conscious throughout, and his condition improved following medical attention, the report states.
In the case of the February flight from Perth, the plane was near Manila when “the Captain informed the First Officer (FO) that he felt out of breath and his vision was impaired. The Captain then declared he was incapacitated.”
The first officer assumed control, and the crew enlisted a medical professional traveling on the flight to offer help, while also contacting a company doctor for advice via an in-flight communications system.
The captain’s condition reportedly improved when he was given oxygen, and the plane similarly requested a priority landing and was met by paramedics.
The AAIA offered no clues as to what may have caused the sudden losses of vision, and said that it expects both investigations to take a year to complete.
While we here at Coconuts HK aren’t exactly doctors, losses of visual acuity among pilots have previously been attributed to a phenomenon called central serous retinopathy (CSR), which involves a build-up of fluid in the eye.
“This fluid accumulation can temporarily or permanently disrupt vision and in many patients is often a recurrent problem,” reads one scholarly article on the case of a US naval pilot who had been grounded due to recurrent attacks.
A study of Israeli military pilots published in the peer-reviewed journal Aviation, Space, and Environmental Medicine found a CSR incidence rate of 1.3 pilots per 1,000, per year, and concluded that “that CSR is a common condition in pilots,” with loss of vision an apparent predictor of whether attacks will recur.
However, in the case of the US naval pilot, doctors were able to successfully treat the CSR, and the aviator was eventually cleared to return to flight duty, albeit with slightly impaired vision in one eye.
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