I never knew much about airplanes before the tragic incident of Malaysia 370. I have been spending a lot of time on Twitter reading various articles and investigations; in one of the articles I read, they stated that unlike transponders, "black boxes" cannot be turned off.
However, each ELT is specifically designed for each aircraft, so it cannot be tampered with. You also cannot turn off the black box, as it runs throughout the flight, recording every 30 to 60 seconds.
Is it really impossible to turn off the black boxes from within the plane?