Co-pilot takes control of the plane when the
pilot goes to the toilet, then surrenders to police asking for asylum in
Switzerland.
Flight ET702 was "forced to proceed" to Geneva international airport after a mayday plea was issued.
Police now have the situation "under control" and there are no injuries to passengers or crew.
The aircraft was on its way from Addis Ababa and was scheduled to arrive in Rome at 4.40am. Instead it landed in Switzerland at 6am local time.
The pilot is reported to have issued a mayday as the plane flew over Sudan.
FlightRadar 24 - an app for mobile devices - showed the flight circling over Geneva several times before landing.
The plane had just 20 minutes of fuel left when it landed.
Sky News's Harriet Hadfield said the airport had not yet opened when the plane landed - and passengers had to wait until it did before disembarking.
She said: "It must have been a very terrifying experience for the passengers on board.
"It seems to have been the case that passengers had to wait until the airport opened. Happily there are no injuries but it must have been a very, very frightening experience."
The airport opened at 7am and is now operating as normal but there have been cancellations and delays.
Ethiopia's information minister Redwan Hussein said: "Our ambassador in Geneva is trying to search information from our passengers.
Ethiopian Airlines said it was making "immediate arrangements to fly its esteemed customers on-board the flight to their intended destinations".
It is unclear how many people were on board but the Boeing 767 300 plane is capable of carrying 252 passengers.
