Air India B788 near Berlin on Jan 19th 2014, complete loss of transponders

An Air India Boeing 787-800, registration VT-ANE performing flight AI-116 from London Heathrow,EN (UK) to Delhi (India), was enroute at FL370 about 30nm west of Berlin (Germany) when the transponder and all other transponders failed, the aircraft became completely invisible to secondary (ATC) radar. The aircraft entered a hold while negotiations began whether the aircraft could continue the flight without transponders, would be able to return to London or would need to divert. In lack of overflight permissions with the failed transponders the aircraft was not permitted to continue to Delhi but was able to eventually return to London, where the aircraft landed safely.

The aircraft is still on the ground in London about 36 hours later, the transponder became visible again about 24 hours after the return but appears still erratic.