Searchers have still not been able to reacquire the signals they heard over the weekend, signals they hope are coming from Malaysia Airlines Flight 370's black boxes.
Officials have released audio of what they heard.
OutFront tonight: Anish Patel, President of Dukane-Seacom, the largest manufacturer of black box pingers. Authorities believe one of his company's pingers was on board Flight 370. He shows Erin Burnett how they work.
He's joined by Richard Quest, CNN Aviation Analyst Miles O'Brien and former Navy Oceanographer Van Gurley.