Speaking after a crisis meeting, he said no hypothesis is to be excluded in the investigation. About half of the passengers onboard were French. The official Algerian news agency said air navigation services lost track of the Swiftair plane 50 minutes after takeoff -- at 0155 GMT. Flight AH5017 had been missing for hours before news was made public.Swiftair, the private Spanish airline, confirmed that 116 people were aboard."In keeping with procedures, Air Algerie has launched its emergency plan," the agency quoted the airline as saying.The flight path of Flight AH5017 from Ouagadougou, the capital of the west African nation of Burkina Faso, to Algiers was not immediately clear.Ougadougou is in a nearly straight line south of Algiers, passing over Mali where unrest continues in the north.