Why can pilots turn off the transponder? Or, why aren’t planes tracked regardless of pilot influence?

Posted by Xesyliad@reddit | aviation | View on Reddit | 7 comments

After watching the Australian 60 Minutes special on MH370, the most notable point was that the Pilot was able to turn off the transponder and prevent the aircraft from being tracked.

What situation would require this in ordinary operation? Couldn’t manufacturers or airlines include rules whereby if a plane deviates from the planned flight path that the aircraft would automatically override and squawk its location regardless?