It seems that it was made into a rule but dropped a year later [0] (by the EASA, so in Europe at least). According to the Wikipedia article on Germanwings 9525,

It seems that it was made into a rule but dropped a year later [0] (by the EASA, so in Europe at least). According to the Wikipedia article on Germanwings 9525, even Germanwings dropped that two-person rule a couple of years later [1]. I don’t know what the FAA rule regarding this is. [0] https://www.easa.europa.eu/en/newsroom-and-events/news/minimum-cockpit-occupancy-easa-issues-revised-safety-information-bulletin https://www.easa.europa.eu/en/newsroom-and-events/news/minim... [1] https://www.bbc.com/news/world-europe-39749803 https://www.bbc.com/news/world-europe-39749803