After takeoff, the hijacker treatened with 3 JUMEX juice cans, (they are the only ones in the world, I believe, made out of steel, not aluminium) strapped with duct tape and some wires (and a bible) and said that it was a bomb, this when flying over water, pilot contacted someone on ground when flying over Veracruz (DUPLO fix and VERACRUZ VOR) by the time it went over Veracruz, people on ground knew about the emergency, BUT either they handled it over emergency channels, we may never know because PUEBLA FEED (mine) was out at the time, I can get Veracruz when W to E, Mexico APP when E to W, so we were in a goog spot if FEED wasn´t out, if they communicated only they knew but I think pilot warned everyone on ground then flew normally to MMMX (Veracruz to APAN fix,then LUCIA or MATEO, then MMMX)
Why hijack the plane so early on flight? because the hijacker wanted to talk to the pilot and to get attention because his goal was to warn president Calderon about a great catastrofic event to happen on Mexican soil (a big earthquake) I don´t remember if when asked to talk to the pilot, did it with the bomb or flashed it after request was refused...
in any case, too bad PUEBLA was out, could have answered some questions..