Disappearing at that altitude, without somebody disabling the transponder, indicates an explosive decompression. These days, that typically only happens with a

Disappearing at that altitude, without somebody disabling the transponder, indicates an explosive decompression. These days, that typically only happens with a bomb or a missile. In the older days, structural failure was a common cause (a blown cargo door UA811, the roof coming off Aloha 243). That just doesn't happen anymore. Another possibility is a hijacking. Another EgyptAir flight was recently hijacked by a man wearing a vest containing fake explosives. The plane landed safely. Some dude took a selfie with the hijacker. A Russian airliner recently exploded over Egypt as well.