reply to post by Zaphod58
Sudden break up would be the most likely, in combination with a loss of electrical systems.
The cabin and cockpit crew have live comms that can be switched on and off in the cockpit and are accesible throughout the plane. These comms are
routed through the flight deck and are used to stay in contact with ground personnel.
The cabin also has a separate comms system, for direct contact with airline staff. Plus an additional emergency channel/alarm, in case of extreme
circumstances, like a hostage situation.
Comms operate through two systems VHF and HF. VHF is the most widely used, mainly to communicate between aircraft and ground crew. HF is used mainly
on commercial flights that cross large sections of ocean. It is worth noting though that comms aren't always available, due to weather and
Commercial passenger jets also use ACARS, which is a subsystem for short burst reporting (i.e. take off or landing confirmations).
On top of this they have transponders which help with aircraft location and ident to other planes or ground control etc. using SSR. Further they use
ADS-B which utilises GNSS to self locate and makes periodic broadcasts via radiowave frequency, to again provide ground staff and air traffic control
with ongoing location updates.
Lastly most aircraft are fitted with multiple ELT's or distress radiobeacons, which broadcast in the case of an emergency.
The thing is, most of these systems are built in with several redundancies, are independent and in the case of ELT's where power is lost from both
primary and backup systems (pretty hard to lose power completely in a commercial passenger jet), will continue to broadcast because they have their
own power supply. In fact it is pretty hard or rare to lose all of the ELT's.
The only circumstance I can imagine, where all standard and emergency comms systems are lost is in the case of rapid and catastrophic
depressurisation. It has happened maybe only once or twice in recent history, where a plane has gone down without any kind of emergency broadcast. Be
that passive or via direct communique.
What could cause the kind of catastrophic failure that would lead a craft to basically vanish and break apart into small enough pieces that they
aren't detected by primary radar is anyones guess. Malaysia airlines have an impressive safety and maintenance record, likewise the 777 and aircraft
rarely break apart due to stress or runaway engine failure and when they do, there is almost always a history of maintenence issues. Say if the
fuselage seperated due to stress and broke apart during cabin depressurisation, these segments would appear on primary radar traces and would only
happen under incredibly extreme circumstances.
That's why I suspect we either aren't being fully informed, or there has been a compound of errors, both mechanical and human (possibly on the ground)
that explain both why the aircraft crashed and why ground staff lost communications. Can't rule out foul play, but it would be awful if true
edit on 8-3-2014 by SuperNintendoChalmers because: (no reason given)