Airplane transponders should come without an off switch
March 19 , 2014
The transponder of the Malaysia Airlines Flight 370 was somehow turned off and Gregg Easterbrook of the New York Times notes that the 9/11 hijackers had also turned the transponders off. Their re-engineering was quite expected after the tragedy but it never ended up happening.
There is no reason for a transponder to be switched off in today's era since "pilots like their locations to be known - for ground assistance, and because the transponder warns other nearby planes of their course and altitude. Only a hijacker at the controls of an aircraft would want the transponder silent."
This is why we need an automatic broadcasting system, which can neither by shut down by the crew or by a hijacker.