Two Ethiopian Airlines pilots fell asleep while flying from Kenya to Ethiopia and missed their landing last Monday.

The pilots for Africa's largest airline allegedly fell asleep during flight ET343 from Khartoum, Kenya, to Addis Ababa, Ethiopia according to the Aviation Herald.

Alerts were raised when the Boeing 737 approached the international airport on August 15 but had not started to descend. While the pilots were fast asleep, the autopilot system kept the plane cruising at 37,000 feet (11,200m).

Air Traffic Control attempted to contact the crew several times without success.

After the plane flew over the runway where it was supposed to land, the autopilot disconnected. This triggered an alarm, which woke up the crew.

Awake and likely startled, the pilots manoeuvred the aircraft around and landed on the runway 25 minutes later.

Incredibly, no one was harmed and the plane landed safely.

Data from the aviation surveillance system ADS-B confirmed the aircraft stayed at 37,000 feet and flew clean over the runway where it was meant to land.

The plane stayed on the runway for about two and a half hours before departing for the next flight.

Posting about the event on Twitter, aviation analyst Alex Macheras described the event as "deeply concerning".

"Ethiopian Airlines Boeing 737 #ET343 was still at cruising altitude of 37,000ft by the time it reached destination Addis Ababa," he wrote.

"Why hadn't it started to descend for landing? Both pilots were asleep."

Macheras blamed pilot fatigue for the incident.

"Pilot fatigue is nothing new, and continues to pose one of the most significant threats to air safety - internationally," he added.