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An area of ocean floor the size of New Hampshire has now been searched in the hunt for missing Malaysia Airlines Flight MH370, authorities said Wednesday as they released new video demonstrating the sonar techniques being used in the operation.

Over 9,200 square miles of the bottom of the southern Indian Ocean have now been searched without any sign of the Boeing 777, the Australia Transportation Safety Bureau said in an operational update. That represents about 40 percent of the total area to be searched, it said. “Assuming no other significant delays with vessels, equipment or from the weather, the current underwater search area may be largely completed around May 2015,” it said.

MH370 disappeared on March 8 last year between Kuala Lumpur and Beijing with 239 people on board. Not a single piece of debris has been found.

Sand artist Sudarsan Pattnaik gives the final touches to his sculpture portraying doomed Air Asia Flight QZ8501 and Malayasia Airlines Flight MH370 on Golden Sea Beach at Puri, India, on December 29, 2014. STRDEL / AFP - Getty Images

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New #MH370 Interview: Dylan Lynch, sonar specialist working on the search for MH370. https://t.co/2fAkcDcqm0 — ATSB (@atsbinfo) February 25, 2015

- Alastair Jamieson