French investigators are to examine a severe turbulence incident a week ago involving an Air France Airbus A330-200 which had been operating the same route as the ill-fated flight AF447.
The Bureau d'Enquetes et d'Analyses says that the 29 November incident to flight AF445, operating Rio de Janeiro-Paris Charles de Gaulle, could yield information valuable to the inquiry into the loss of AF447, another A330-200, on 1 June.
BEA is set to publish, on 17 December, a second investigation report into the south Atlantic crash.
The AF447 inquiry has been forced to proceed without the crucial data from the A330's two flight recorders, which have yet to be recovered.
But the upset involving AF445, the BEA says, "might provide further insight" into the accident.
The aircraft (F-GZCK) encountered severe turbulence about four hours after departing Rio, and the pilots brought the aircraft down to a lower flight level.
Air France says that the crew could not raise air traffic control and opted instead to transmit an emergency message over the radio to advise of the change in altitude.
"After half an hour of moderate to severe turbulence, the flight continued normally," the carrier adds.
Air France says the cockpit crew carried out its actions "in strict accordance with procedures". The A330 was transporting 203 passengers and 12 crew.
AF447 had been almost four hours into its journey, and in the vicinity of storm activity, at the time of its disappearance.