formulaben,
Before you roll your eyes..explain what can turn the transponder off on the 777. Do not give me the electrical failure. Too many redundancies. Including RAT. This one is a true puzzle. One SAFETY system you never want off unless you are up to a mischief. So yes, you bet human hand turned it off.
So what happens here:
Transponder fault forces AI flight to return to Delhi | The Indian Express
Does anyone have further details on recent transponder fault with AI 127 (another 777)