They only awoke after the autopilot disconnected.
An Ethiopian Airlines flight missed its landing last week after its two pilots fell asleep, according to reports.
Aviation Herald states that the incident involved Flight ET-343 which was flying from Khartoum in Sudan to Addis Ababa in Ethiopia on Monday (15 August).
The outlet says that the plane was at a cruising altitude of 37,000ft when it was supposed to start the descent into the destination airport.
When it failed to do, Air Traffic Control attempted to contact the flight's crew several times without success.
However, after the autopilot disconnected, an alarm woke the pilots of the Boeing 737-800 up.
They then guided the flight for a safe landing on the runway about 25 minutes later.
Sharing the Aviation Herald's report on the incident, aviation analyst Alex Macheras described it as "deeply concerning".
"Pilot fatigue is nothing new, and continues to pose one of the most significant threats to air safety internationally," he added.
https://twitter.com/AlexInAir/status/1560386182055428097
