Posted on 03/15/2014 2:24:35 PM PDT by nickcarraway
If multiple communication systems aboard Flight 370 were manually disabled, as investigators increasingly suspect happened, it would have required detailed knowledge of the long-range Boeing777's inner workings.
The Wall Street Journal said the first loss of the jet's transponder, which communicates the jet's position, speed and call sign to air traffic control radar, would require disabling a circuit breaker above and behind an overhead panel.
Pilots rarely, if ever, need to access the circuit breakers, which are reserved for maintenance personnel.
Pulling one specific circuit breaker, which is labeled, would render inoperative both of the 777's transponders, according to documents reviewed by WSJ and bolstered by comments from aviation industry officials and those who have worked with the 777.
Becoming familiar with the 777's systems requires extensive training for pilots and aircraft mechanics alike, experts said. However, considerable technical data on the airplane is also available online in discussion groups or other websites.
Investigators are trying to establish a sequence of events that transpired on the jet, which vanished from radar March 8, most critically the loss of communication.
The shutdown of the on board reporting system shortly after the jet was last seen on radar, can be performed in a series of keystrokes on either of the cockpit's two flight management computers in the cockpit.
The computers are used to set the performance of the engines on takeoff, plan the route, as well as other functions to guide the 777.
After vanishing, the jet's satellite communications system continued to ping orbiting satellites for at least five hours.
The pings ceased at a point over the Indian Ocean, while the aircraft was at a normal cruise altitude, say two people familiar with the jet's last known position.
Investigators are trying to understand that loss, and whether or not "something catastrophic happened or someone switched off" the satellite communication system, says one of the people.
The longest week
A physical disconnection of the satellite communications system would require extremely detailed knowledge of the aircraft, its internal structure and its systems.
The satellite data system is spread across the aircraft and disabling it would require physical access to key components.
Disconnecting the satellite data system from the jet's central computer, known as AIMS, would disable its transmission. The central computer can be reached from inside the jet while it is flying, but its whereabouts would have to be known by someone deeply familiar with the 777.
Getting into the area housing the 777's computers would "not take a lot" of knowledge, said an aviation professional who has worked with the 777.
However, this person added, "to know what to do there to disable" systems would require considerable understanding of the jet's inner workings.
Some airlines outfit the access hatch to the area below the floor with a special screw to prevent unauthorized intrusion, the person added.
Orbiting satellites are designed to check in with the aircraft's satellite-communication system hourly if no data is received during that time.
The pings from the aircraft became a subject of scrutiny earlier this week, said a person familiar with the matter, several days after the plane first went missing.
Because the pings between the satellite and the aircraft registered that the aircraft's satellite communications system was healthy and able to transmit, the data did not immediately raise any red flags in the hours after the jet's disappearance.
At first, the origin of the final ping from the Malaysia Airlines jet seemed like an anomaly to investigators, according to a person familiar with the matter, given that the plane was believed to have crashed off the coast of Vietnam, hundreds if not thousands of miles from the location of the final ping.
What is a transponder? Until just a few years ago, the satellite communication system used by jetliners didn't include data on an aircraft's location in the pings, the electronic equivalent of handshakes used to establish initial contact.
For instance, before Air France Flight 447 crashed into the Atlantic Ocean in 2009, the jet sent some diagnostic data indicating problems with various onboard systems, including the autopilot's deactivation. But notably the plane's position wasn't transmitted with that data.
Partly as a result it took nearly two years to locate the plane's "black boxes" and the majority of the wreckage. In the case of the missing Malaysian jetliner, precise locations were provided. However, it is unclear why the transmission ceased and where the plane may have ended up after the final ping.
An expert would be needed to disable the systems on the missing Malaysia Airlines jet. The headline to an earlier version of this story incorrectly said an insider would be needed.
At first I thought with the number of people with cellphones on the plane someone would call for help. But then I remembered there are electronic devices which disable cell phones ability to make/receive calls that are readily available and cheap.
There are several wrong statements in this story but this is a fact.
I think a bigger problem is that cellphones go out of range. Once they are off-shore, and 20 or 30 miles from a celltower, they do not work.
Some have commented on how phones worked during 9/11. That’s not relevant here, because the 9/11 plane paths were entirely over land, where cell towers are plentiful.
Presumably there are bound manuals onboard that tell you have to disable most anything. In the case of an electrical short/fire in a given system you would need these instructions. With some planning you wouldn’t need to fumble with a four inch think binder, but a single peace of paper with only those exact instructions or you could memorize the fuse panel location, fuse locations, sizes and/or slot numbers.
Bookmark
If someone wants to steal something, they can do the research.
Is it possible to jam the transponder signal without actually turning off the equipment?
Why are the systems made available to the crew in such a way that they can be disabled? What’s the real world, legitimate reason for crew disabling these systems?
Seems simple enough. Were all maintenance personnel accounted for or is it being covered up?
If the plane was over the ocean when it went to 45,000 feet (IMO as part of a plan to decompress the cabin and kill the passengers), the plane would have been out of cell phone range. I think this was a sick but well-conceived theft of the plane by either the pilot, co-pilot or a crew member who had access to the cockpit.
“What’s the real world, legitimate reason for crew disabling these systems?”
Electrical problems. Shorts. Fires.
You’d want to be able to shut them down in cases like this.
The transponder too? Seems like that logic could extend to shutting down the black box. Thanks for the reply :)
Generally, no. You do not jam the transmitter - you jam the receiver. But the receiver is on an Iridium satellite. If you have to jam from the transmitter's position, you have to use 100 times as much power, and an antenna that is just as good - and even that may be not enough, depending on the modulation of the signal.
Thank you too much.
For the ACARS it gives us the ability to reset the system if it is not functioning propey. Similar to cntr-alt-del
I’ve always heard it’s to be able kill the power so you can extinguish an electrical fire.
Heard or read .. can't remember ACARS was disabled. Or experts (dime a dozen) believe it was disabled.
Have some diabolical terrorists refined the technology of ‘BAIT CARS’???
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