Panic erupted on a flight from Australia when the pilot suddenly became incapacitated and passengers were called on to help.
The Cathay Pacific plane, which was flying from Perth to Hong Kong, was over an hour away from its destination on February 21 when the call was made.
The captain had been having trouble breathing and his eyesight was becoming blurry when the co-pilot had to take command, according to a report by the Air Accident Investigation Authority.
A desperate call to passengers was made for anyone with medical experience to help as the Airbus A350, just was flying over Manila.
The flight had 270 passengers and 13 crew members on board.
A passenger who was a medical professional assisted and the captain was given oxygen while a company doctor gave advice from Hong Kong.
Hong Kong air traffic control were called and a pan-pan – the emergency call below mayday – was declared.
The plane then dropped to a lower altitude to decrease cabin pressure to help with the captain's breathing, the report said.
Just after 7am local time the plane landed at Hong Kong airport where paramedics were waiting to treat the captain.
The pilot has 25,000 hours flying experience and 97 hours command time for the aircraft model, the report said.
His medical certificate was class 1.
A similar incident involving another Cathay Pacific airline captain happened on January 26 on a flight between Sapporo and Hong Kong.
The captain on flight CX583, carrying 348 passengers and 16 crew suffered a sudden loss of vision.
This lasted for around half an hour and the co-pilot had to take control of the Boeing 777 west of Taiwan, according to the preliminary report .
What is a Pan-Pan?
Pan-Pan is the international call signal declaring there is an urgent situation on board an aircraft but there is no immediate danger to life or to the vehicle.
It is referred to as a state of urgency requiring priority from the air navigation service provider.
It requires an investigation by the air navigation service provider, which in these two cases is Hong Kong’s Civil Aviation Department.
The authority, which declared both 'flight crew incapacitation' events as 'serious incidents', said an investigation team was trying to determine the cause.
'The [authority] will continue to collect and study all relevant information in order to determine the circumstances and causes of the serious incidents,' a spokesman said.
'More in-depth investigation and analysis have to be conducted before any conclusion can be drawn.'
A Cathay Pacific spokeswoman told The Star Online: 'Safety is in the consideration of everything we do and in each case, the operating crew acted in accordance with Cathay Pacific's standard operating procedures regarding pilot incapacitation.'
She added that the airline would be cooperating with the investigations fully.