The search for Malaysia Airlines Flight MH370 resumed on Sunday, more than a month after the plane disappeared from the radar. It is now feared that the batteries of the black box may have finally died. making the search for the jet almost impossible.

The sad news for the various rescue teams assisting in the search for the jet, as confirmed by Australian Prime Minister Tony Abbott, is that the “pings” which were being picked up in the search in the remote southern Indian Ocean, appear to have stopped.

Officials have reported that they are quietly confident that they know approximately where the missing jet’s black box is, although the latest signal, picked up on Thursday, was confirmed as not having been from the missing jet.

The search to find the jet has intensified as the batteries of the black box are already way past their 30-day life span. If and when searchers locate the missing plane, they will deploy a robot known as an Autonomous Underwater Vehicle to find it.

The Australian team which is handling the underwater search said on Saturday: “Work continues in an effort to narrow the underwater search area for when the Autonomous Underwater Vehicle is deployed. There have been no confirmed acoustic detections over the past 24 hours.”

The search for the jet has so far proven to be the most expensive, expansive and biggest rescue operation of its kind in aviation history. It has also come to light that the co-pilot on the flight tried to use his mobile phone just moments after the jet was taken off course.

An unmanned submarine, named bluefin-21, is aboard the Ocean Shield and will be deployed if a clear reading of the missing jet’s black box is received – or, probably, even it there are no further signals.. The submarine will then search for wreckage on the ocean bed, which is roughly 2.8 miles (4.5 km) below sea level.