article_snippet.sent: The search and rescue phase becomes a search and recovery phase, with it moving a few days later to an underwater phase using an autonomous underwater vehicle and a bathymetry survey covering an area around 430 miles (692km) long and 50 miles (80km) wide.
article_snippet.sent: After a four-month lull, it is announced that the underwater search, involving depths of up to 3.7 miles (6km), would resume at the end of September.
article_snippet.sent: the underwater search, involving depths of up to 3.7 miles (6km) involves ships dragging sonar devices called towfish through the water about 330ft (100m) above the seabed to hunt for wreckage.
article_snippet.sent: towfish are equipped with jet fuel sensors and can transmit data to those on board the vessels.