I was surprised when I read this report as I was not aware that European airlines have not adopted the "two-persons-in-the-cockpit" rule or the "four-eye-rule". It was recommended in 2016, but left to the airlines to adopt the practice, or not (link). It is a requirement in the US (link).
Lufthansa flight flew without a pilot for 10 minutes after copilot fainted, report finds
A Lufthansa flight with 205 people on board went without a pilot for 10 minutes last year after the copilot fainted while he was alone in the cockpit, according to a new report from Spain’s accident investigation authority.
The captain had briefly left the cockpit to use the lavatory when the copilot fainted during a flight from Frankfurt to Seville, Spain, on February 17, 2024, said the report from the agency, called CIAIAC.
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The report said the captain returned from the bathroom and tried to open the cockpit door with a regular opening code, which chimes the cockpit. The captain made five attempts at this and a cockpit crew member also placed an intercom call to the flight deck. With no response, the captain used an emergency code to gain access and took control of the aircraft.
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