Regardless of what caused a Malaysia Airlines jet to disappear from the sky over the weekend, air-safety experts predict it will reignite debate over new technology designed to provide immediate clues for investigators in the event of a crash.

Search teams on Monday began their third day looking for signs of the 12-year-old Boeing Co. 777-200ER that disappeared just after midnight early Saturday local time while cruising at 35,000 feet en route to Beijing from Kuala Lumpur. Investigators say they are delving into a range...