Finding a missing Malaysia Airlines plane may hinge on whether searchers can narrow down where they need to look using satellite data that is inexact and has never been used for that purpose before, search and rescue experts say.

Authorities now believe someone on board the Boeing 777 shut down part of the aircraft’s messaging system about the same time the plane with 239 people on board disappeared from civilian radar. But an Inmarsat satellite was able to automatically connect with a portion of the messaging system that remained in operation, similar to a phone call that just rings because no one is on the other end to pick it up and provide information. No location information was exchanged, but the satellite continued to identify the plane once an hour for four to five hours after it disappeared from radar screens.