Military planes located new debris from Air France Flight 447 Wednesday while investigators focused on a nightmarish ordeal in which the jetliner broke up over the Atlantic as it flew through a violent storm.

Heavy weather delayed until next week the arrival of deep-water submersibles considered key to finding the black box voice and data recorders that will help answer the question of what happened to the airliner, which disappeared Sunday with 228 people on board. But even with the equipment, the lead French investigator questioned whether the recorders would ever be found in such a deep and rugged part of the ocean.

As the first Brazilian military ships neared the search area, investigators were relying heavily on the plane’s automated messages to help reconstruct what happened to the jet as it flew through towering thunderstorms. They detail a series of failures that end with its systems shutting down, suggesting the plane broke apart in the sky, according to an aviation industry official with knowledge of the investigation.