[cashflyer]

Even if they pulled breakers, the ELT is self contained with it's own power supply (batteries).
Any significant impact would trigger it.

On land, OK. But if it sank, the water would block the signal, and not all ELTs are water proof. It would have to transmit before sinking.

406mhz ELTs (required on all US* transport planes) update their GPS data every 15 seconds and upon being triggered send a "burst transmission" to the satellite with GPS position data and the identification code of the aircraft it is installed on. So if it did not send the transmission, my guess is that it was never triggered by an impact, or that it was destroyed in a way that kept it from sending data (like a massive explosion), or that it plunged into the water and sank immediately (ie, within seconds).

Or, maybe it did send the data.



*yes, this is a Malaysian plane and I don't know if they play by the same rules as our planes