Malaysia Airlines 777 loses contact...not found

[KitaCam]

Sorry if this hasn't been mentioned...
But...where were the Vietnamese who didn't hear/get the switch-over call???? That should have sent them into a panic if not alert mode to get others involved to find it when it was still supposed to be in the air...
and...
If current theory is correct, the plane DID fly over land again (Malaysia) so why no cell calls sent/heard...?

 

[Blaze]

Originally Posted By: friendly_jacek
Originally Posted By: Blaze
FBI says they can get info (the first 2hrs) off the voice flight recorder if its been recorded over.


How is it possible? This is not magnetic tape, this is digital recording in memory chips.
I wondered how that was possible too but they interviewed an FBI investigator and that is exactly what he said.

 

[SwampSurvivor]

CNN has certainly been milking this for all its worth. They have covered nothing BUT this.

That's typical of mainstream media today. Everything has to be sensationalized. Just like snow storms. Every time we get a snow "event" (can't say storm ...) where we are expected to get 3 or more inches as predicted by NWS, the Weather Channel and local "news" outlets go crazy.

A day of snow to with 3 inches of snow, no wind and mid 20s temperature to the NWS is 30 feet, blowing winds, -459F wind chills and the world is going to come to and end.

It's all about ratings.

 

[JDW]

Originally Posted By: Miller88
CNN has certainly been milking this for all its worth. They have covered nothing BUT this.

That's typical of mainstream media today. Everything has to be sensationalized. Just like snow storms. Every time we get a snow "event" (can't say storm ...) where we are expected to get 3 or more inches as predicted by NWS, the Weather Channel and local "news" outlets go crazy.

A day of snow to with 3 inches of snow, no wind and mid 20s temperature to the NWS is 30 feet, blowing winds, -459F wind chills and the world is going to come to and end.

It's all about ratings.


Got that right, I want even watch TWC anymore. It used to be a fav of mine.

 

[Doog]

Flight 370 never took off. It was taxied into a hangar where all of the passengers and crew were chloroformed and sold into human slavery in South America. The plane was disassembled by SPECTRE agents and taken to Ernst Blofelds private underwater headquarters somewhere at the bottom of the South Indian Ocean. Emilio Largo headed the operation (Emilio was actually never killed bu Domino Vitali and is still alive today.)

The reason this all happened was that SPECTRE was smuggling stolen nuclear weapon triggers in the cargo hold of the Boeing 777 and MI6 and CIA operatives were on to the scheme.

 

[Astro14]

Originally Posted By: friendly_jacek
Originally Posted By: Blaze
FBI says they can get info (the first 2hrs) off the voice flight recorder if its been recorded over.


How is it possible? This is not magnetic tape, this is digital recording in memory chips.


It is digital.

FLIGHT DECK VOICE RECORDER SYSTEM
A flight deck voice recorder digitally records four audio channels for the last 2 hours. Audio older than 2 hours is erased. Three of the channels record all receptions and transmissions from the audio control panels. The fourth channel records audio from the area microphone installed on the overhead panel.

The flight deck voice recorder system operates anytime AC power is available.

So, if the recorder is found, the last two hours will be on there. What was said in the cockpit prior to that point will not be on there. Of interest would be what was said when the airplane turned, but that likely won't be on there unless all AC power was off (this is not likely, batteries provide AC power via an inverter for emergencies)....alternatively, if the crew pulled the CB for the FDVR, then we might get nothing...

 

[Quattro Pete]

Originally Posted By: Astro14
A flight deck voice recorder digitally records four audio channels for the last 2 hours. Audio older than 2 hours is erased.

Is there any particular reason they only keep the last 2 hours? Memory/storage is fairly cheap these days, even if it's some specialized memory needed in this particular case.

 

[Astro14]

Airplane was built in 1995. FAA sets the standards for how long they have to record...

In general, for accident investigation, the preceding two hours will contain everything of interest that led up to the accident. This is one case where that might not be true. Retrofitting FDVRs with higher capacity costs $$...so, unless it's a regulatory requirement...airlines won't spend the $$.

They used to record only the last 30 minutes...and again, that was long enough for the entire accident sequence to be recorded in detail.

 

[supton]

And, how many accidents require piecing together the last 10 hours of flight info?

Of course, in this case, it wouldn't matter if recorded the last week of flight time.

 

[D189379]

Originally Posted By: Quattro Pete
Originally Posted By: Astro14
A flight deck voice recorder digitally records four audio channels for the last 2 hours. Audio older than 2 hours is erased.

Is there any particular reason they only keep the last 2 hours? Memory/storage is fairly cheap these days, even if it's some specialized memory needed in this particular case.



I think the pilot union was involved, as recording entire flights was viewed as an invasion of privacy.

 

[D189379]

Originally Posted By: Astro14


So, if the recorder is found, the last two hours will be on there. What was said in the cockpit prior to that point will not be on there. Of interest would be what was said when the airplane turned, but that likely won't be on there unless all AC power was off (this is not likely, batteries provide AC power via an inverter for emergencies)


The last 2 hours should still be somewhat telling if there are alarms and warnings going off or not.

 

[friendly_jacek]

Originally Posted By: D189379
Originally Posted By: Astro14


So, if the recorder is found, the last two hours will be on there. What was said in the cockpit prior to that point will not be on there. Of interest would be what was said when the airplane turned, but that likely won't be on there unless all AC power was off (this is not likely, batteries provide AC power via an inverter for emergencies)


The last 2 hours should still be somewhat telling if there are alarms and warnings going off or not.


If we ever find one. The chances are not 100% IMHO.

http://en.wikipedia.org/wiki/List_of_unrecovered_flight_recorders

 

[Astro14]

Originally Posted By: D189379
Originally Posted By: Quattro Pete
Originally Posted By: Astro14
A flight deck voice recorder digitally records four audio channels for the last 2 hours. Audio older than 2 hours is erased.

Is there any particular reason they only keep the last 2 hours? Memory/storage is fairly cheap these days, even if it's some specialized memory needed in this particular case.



I think the pilot union was involved, as recording entire flights was viewed as an invasion of privacy.


Not true.

We are opposed to video recording of the cockpit. That truly would be an invasion of privacy.

If you really wanted to start making a difference, start recording every operating room, every hospital room, and every doctor's office. Medical professional mistakes kill over 100,000 every year in the US alone. That's at least a 777 every day.

You wouldn't mind that conversation, and your disrobed self, being recorded to be reviewed for mistakes, would you? After all, it's for your safety....

 

[Blaze]

On digital voice recorders you can retrieve deleted files but you can't retrieve data that has been recorded over? When something gets recorded over in digital format then all files of it are gone? How does that work?

 

[Blaze]

Astro, On the flight recorder...would it show temperature changes (possible fire) in various sections of the aircraft?

 

[Astro14]

More recent airplanes, like the 777, record more flight parameters on their flight data recorder. It's separate from the cockpit voice data recorder and our books don't mention its capability. I suspect that it records over 100 flight details continuously, but I don't know for certain what those parameters are. Warnings are likely one recorded parameter, but again, I've got no details on that.

The central maintenance computer should make note of any exceedance that would show up on the crew warning system (EICAS). That data goes back to the company via ACARS. ACARS appears to have been working for this flight because engine data updates were received via the same pathway.

Edit: here's the detail. Looks like 88 parameters required for newer airplanes, including 777.

http://www.boeing.com/commercial/aeromagazine/aero_02/textonly/s01txt.html

 

[Astro14]

Originally Posted By: Blaze
On digital voice recorders you can retrieve deleted files but you can't retrieve data that has been recorded over? When something gets recorded over in digital format then all files of it are gone? How does that work?


That's from a reporter quoting a source. I'm quite certain the details were garbled. The folks in media seem to have difficulty accurately reporting any kind of technical detail. They'll tell you that they try to make it accessible for their audience, but I suspect that they really don't understand engineering, or how things work...that's what attracted them to the world of journalism in the first place....

 

[PandaBear]

Originally Posted By: Blaze
Originally Posted By: friendly_jacek
Originally Posted By: Blaze
FBI says they can get info (the first 2hrs) off the voice flight recorder if its been recorded over.


How is it possible? This is not magnetic tape, this is digital recording in memory chips.
I wondered how that was possible too but they interviewed an FBI investigator and that is exactly what he said.


Assume it is based on a flash memory like device, I may be able to explain.

The things are recorded / erased may be just writing a "mark as dirty" to be really erased later flag somewhere in the file system, like how your OS just put a ? in front of the file to be erased on your file system partition until it runs out of space or what not. On a flight recorder, it may have enough space to wait till a real erase later, as in each session of flight recording is only 24 hours but the storage can hold 1000 hours. Then it will not be really erased.

Another possibility is, if they write something over, there's residue magnetic (hard drive or tape) / electric charge (flash memory) noise that can be read in analog value to extract the previous data. So for example your 15V value on flash memory cell is 1 and 0V is 0, and you erase them all for new data should have mark them all 15V, but due to residue value from previous session, you will end up with 15.2V and 14.8V (for example). The same for magnetic recording due to overwriting magnetic materials slightly off track.

This is the reason why you need to write random values in multiple pass if you truly want to disguise what you did in the past on your storage.

 

[PandaBear]

Originally Posted By: Blaze
On digital voice recorders you can retrieve deleted files but you can't retrieve data that has been recorded over? When something gets recorded over in digital format then all files of it are gone? How does that work?


Everything is down to analog when you talk about physics, so if they really want to (i.e. if they found Vladimir Putin's hard drive) they can do a microscopic scan of the entire flash memory / magnetic hard drive and then map the analog reading to the known physical property of the material, and extract the "residue" value not available from the on board electronics.

This is of course extremely expensive and must be done by a team of experts.

 

[Astro14]

Given the age of the recorders. It may not be "erased" as much as "over written" because of the limited storage capability. In which case, the previous data would not be recoverable. The FBI may have formidable technical capability, but unless the expert who said this has seen the inside of a CVR, he's talking about something with which he has no experience. This might be a circa 1995 flash memory...So, while technically true in other instances, it likely isn't true at all in this case, and he becomes another "expert" with no relevant information to this case.

That seems to be a theme here....

Still, we have to find the airplane, and soon, or we may never find these. You have to be pretty close to the crash site to pick up the beacons. Water severely attenuates their range, and the geography of a mountainous ocean floor blocks radio signals as well.