The vessel is equipped with sonar that can pick up the underwater "pings" emitted by the recorders. It is specialized in maritime surveillance, and rescue and marine police missions.
The 80-meter (262-foot) ship left its Mediterranean home port of Toulon Friday with a crew of 90, including two judicial investigators.
The search area is roughly halfway between Egypt's coastal city of Alexandria and the Greek island of Crete, where water is 8,000 to 10,000 feet (2,440 to 3,050 meters) deep.