French airliner flight data may never be found

French aviation officials have said they may never find the flight data recorders of an Air France jet that went missing over the Atlantic.



The officials have promised a thorough investigation but say the circumstances are very difficult.



Flight AF 447 was heading from Rio de Janeiro to Paris with 228 people on board on Monday when it disappeared over the ocean.



A memorial service has been held at the Notre Dame Cathedral in Paris, attended by French President Nicolas Sarkozy.



Mourners also heard a message of condolence from the Pope.