[tzs]

It is extremely unlikely. They only have enough power for about 30 days, and they are generally only on reasonably large, commercial, aircraft, or on military aircraft.

If they picked up a black box, and it is not from MH370, then it would mean that another large commercial plane went down there within the last 30 days and either no one noticed it was missing or it was somehow kept secret, or that some military lost a plane there within the last 30 days and kept it secret.