“This is so rare, it is absolutely baffling and it’s baffling that we don’t have any better answers this long after the mishap actually occurred,” ABC News aviation consultant Col. Stephen Ganyard said. “So, lots of questions to be answered, [but] there’s very little direct evidence, very few facts that we can go on.”

Ganyard says the aircraft has a great safety record…

Even though the plane likely crashed in relatively shallow water, which makes these pingers work more effectively, underwater plane crashes are notoriously difficult to pinpoint.

The last flight to disappear like this was an Air France flight in 2009. It was two years before the black box was found and the cause of the crash — a combination of mechanical error and pilot oversight — determined.