The move comes as it could become difficult for human searchers to locate the missing plane if it's resting two miles down or more under the Indian Ocean.
According to Fox News, such unmanned subs, called autonomous underwater vehicles or AUVs, played a critical role in locating the carcass of a lost Air France jet in 2011, two years after it crashed in the middle of the south Atlantic. The find allowed searchers to recover the black boxes that revealed the malfunctions behind the tragedy.
Before unmanned subs can be sent down to search for the Malaysian jet, the search zone must be narrowed considerably. That depends on finding wreckage on the surface. Unmanned subs are also far more flexible.