PERTH (AFP) - The first dive by a mini-submarine hunting for Malaysian jet MH370 detected nothing of interest, with the mission aborted after breaching the machine's maximum operating depth, the US Navy said on Tuesday.
The unmanned Autonomous Underwater Vehicle (AUV) Bluefin-21 was undamaged and set for a second sonar sweep of the Indian Ocean seabed during the day, weather permitting.
"To account for inconsistencies with the sea floor, the search profile is being adjusted to extend the sonar search for as long as possible," a US statement said.
"Bluefin-21 was unable to complete its first search mission after six hours, due to breaching maximum operating depth." The vehicle was recovered and six hours' worth of data downloaded.
"The data was analysed and no objects of interest were found," the statement said.
"The vehicle is in good material and working condition." The navy estimated it would take the AUV from six weeks to two months to scan the entire search area.
The submarine equipped with sonar deployed Monday night from the Australian ship Ocean Shield, which has spearheaded the hunt for the Boeing 777 that vanished on March 8 with 239 people aboard.
"The AUV was programmed to fly at an altitude of 30 meters over the ocean floor; however, when the vehicle reached its maximum operating depth of 4,500 meters, its built-in safety feature returned it to the surface," the navy said.
Australia's Joint Agency Coordination Centre said the AUV had been due to spend 16 hours collecting data.