Australian investigators are considering the possibility that cosmic radiation caused a mid-air emergency aboard a Qantas jet last year.
The Australian Transport Safety Bureau still does not know why the Airbus A330 suddenly dropped 100m over Western Australia on a flight from Singapore on 8 October but it has ruled out any connection between the incident and the fatal crash of an Air France airbus into the Atlantic earlier this year.
The bureau says a different sequence of events led up to both incidents.
The investigators are considering if a neutron hit by cosmic radiation may have been responsible for the computer fault at the centre of the incident.
More than 100 people were injured, 12 of them seriously.
The bureau has promised to deliver another report into the incident in the second half of 2010.