Investigators have focused on incorrect speed readings as one potential factor in the crash.
With Brazil and France disagreeing about whether pieces of the jet have even been found in the Atlantic, investigators are using the last messages sent by the plane to determine the cause and try to avoid future disasters.
Air France declined to comment on the memo obtained by The Associated Press, saying it was for pilots only.
Airbus said the matter was part of the investigation into the crash that killed 228 people flying from Rio de Janeiro to Paris Sunday. The Bureau of Investigation and Analysis, which is leading the French probe of the crash, said it would address all questions at a Saturday news conference.