There are a few reasons why compression may not be good fit for this application. The CVR records the pilot headsets and ambient cockpit noise in a continuous loop. Time and frequency analysis is an important aspect of the data so it would have to be lossless compression. This is used for instance to analyze engine performance or structural failures. Even for pilot comms, good fidelity is important for identifying the crew members and checking for dimished performance factors. This drives up the costs and lowers resiliency. To have useful compression first you need statistical redundancy, of which there is not a lot for turbulence noise. Then you need a buffer, which means losing the last uncompressed chunk of sound. If you increase the buffer size you lose more. If you decrease your compression ratio tanks. Also losing a critical section of data on impact could compromise the whole set.
Well all they’ll get from this one when they find it is a Simon & Garfunkel song.
After I wrote that I did a bit of searching and found out that the FDR and CVR can be accessed from a panel on the rear of the cabin. So I was wrong.
This probably has been suggested but, could the plane had suffered massive damage that both decompressed the fuselage pretty much instantaneously and severed the power cables for the transponder and other systems yet the autopilot retained the capability to sustain level flight?
For example, an uncontained fan or compressor failure on one of the engines, as with that Qantas A380 some time ago, except that the fan/compressor actually rips the fuselage of the plane, so pressurization gone in a blink, everyone knocked out in seconds, transponder and other stuff stops working but the autopilot keeps the plane flying straight (after perhaps a turn due to the engine failure?)
Barring engine catastrophic failure it could had been a structural failure, a bomb or a fire. In any case a very sudden decompression seems a very likely part of the puzzle.
I did more than a bit of searching and I couldn’t find any information whether the FDR/CVR is accessible from inside but that makes sense to me because a few meters between the rear of the cabin/cargo hold and the tail proper would not make much difference in survivability but it would make a huge difference in engineering design.
if this was a large coordinated effort by multiple people it would have been picked up in the criminal investigation so we can assume it was one of the pilots.
To have the freedom of motion to remove and dump the blackboxes it would require everyone else on board to be incapacitated, which fits with the deliberate decompression theory.
No they are not voice activated. Their purpose is not just to record voice but also to record ambient sounds in the cockpit. There is an ambient microphone specifically for this as well as recording inputs from the intercom system.
The cockpit voice recorder is unlikely to reveal anything interesting given it is on a two hour loop.
A catastrophic event near Vietnam is the most likely explanation for this aeroplane’s disappearance.
The counter-argument however is strong: a crisis explains the turn west back to Malaysia but the further turn south on automatic pilot flight into the landless Indian Ocean implies active steps in the flight deck. Therein lies the mystery.
Suicide by pilot is a popular theme but it is a vanishingly rare event in real life. Furthermore suicide is a violently aggressive action with the hope of immediate oblivion. It isn’t something planned out for 7 hours time.
Exactly. While well-planned-out suicides do happen, the vast majority of suicides are impulse decisions (ie, someone is feeling overwhelmed because they just got fired or something, they see a bus coming and decide to jump in front of it). If the person is able to calm down before they kill themselves, they’ll usually not go through with it.
A suicidal pilot might put his plane into a fatal nosedive. He would not plan out a multi-hour flight into the middle of the ocean. Even if he did, he would most likely abandon the plan after the initial wave of desparation passed.
He might not have remained conscious for the last hours of the flight. He might have killed himself, perhaps simply from shutting off cabin pressure and killing everyone else, right after setting the plane to fly into eternity.
Pilot suicides are perhaps “vanishingly rare”, but there are two and probably three known cases anyway - this would be the fourth.
It’s at least four known or strongly suspected (Silk Air, LAM, Egypt Air, Royal Air Maroc). Apparently “vanishingly rare” means once every five years or so.
But if such a pilot diverted from his flight path, shut down ACARS, transponder, and had done so for several minutes, he would have probably felt he had passed the point of no return, even if he did reverse course and head to his original destination.
There would likely be extensive inquiry and investigation, possibly ending his career, and other consequences too.
A fire or explosion in the forward compartment could have taken out the comm antenna pretty easily. The plane was carrying lithium batteries which are problematic if they catch fire.
This is a very reasonable explanation (much moreseo than the one-in-a-billion elaborate suicide theory) but it still doesn’t explain why the plane was put on a course out into the vast nothingness of the southern Indian Ocean. If there was a fire on board, then presumably the pilots would try to land at the closest available airport. If they were incapacitated and couldn’t land, then who set the autopilot for Buttfuck, Nowhere?
It’s only over recording while it’s on - my response was to a previous poster who assumed that the pilot/hijacker flipped the breakers on the CVR/FDR when they took over the plane - thus in that scenario the CVR would have information up to the moment of takeover, and instead be missing the rest of the flight.
As was stated up thread onboard fires give the plane a life measured in seconds or minutes not hours.
The point being that neither would show what actually happened - the only recordings would show a normal flight, and then suddenly stop.
Engines don’t care if the comm system is destroyed. The passenger compartment is isolated from the cargo bays and the crew is isolated from both with it’s own oxygen supply.
Engines *do *care about having a structurally intact airplane attached to them.
Almost the entire flight of a commercial airplane is automated. The question then is the route. Was it a previous route called up or something programmed at the time or individual inputs made point-to-point.
and? The plane flew for 7 hrs. What’s your point? Not every fire on an airplane destroys it.