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Mar 12, 2014, 06:43 PM
AustinTatious
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Just a random thought, pure speculation here.

Many aircraft have an "EDM". Or "Emergency Decent Mode"

In the aircraft I fly, when activated due to a loss of cabin pressure the autopilot will make a 90 degree turn to the left and the autothrottles will bring the engines to idle ans start a max decent to 15000 feet..

It is possible they had a dual engine failure and lost pressurization due to the absence of incoming bleed air.

They could have got their mask on or possibly passed out. You have to manually switch you mic selector to oxy mask in order to continue to communicate. It is possible they forgot to do this while they were busy trying to relight engines. It is also possible they were unconcious.

Had they been unconcious if they regained conciousness at low altitude they may have been out of VHF range so no calls would have been heard except by other airborn traffic on that frequency.

It is also possible that if both engines did flame out that the did not fully regain conciousness when the autopilot leveled off which would have no doubt resulted in a stall (since the engines were dead.)

This would account for the turn to the left, the lack of radio calls AND debris being found near the expected route.

Just speculation.
Mar 12, 2014, 06:51 PM
Registered User
Pretty good thinking. Why the initial 90 degree left turn by the autopilot?
Mar 12, 2014, 06:53 PM
56S
56S
Certified Balsa Breaker
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Quote:
Originally Posted by Big Foot 48
The Chinese have released some sat images of large objects in the water on the ORIGINAL flight path. http://www.cnn.com/2014/03/12/world/...ane/index.html
According to the report I saw these parts were two to four times the size of a medium sized home. Maybe an area of many floating parts?
Mar 12, 2014, 06:55 PM
I'd rather be Flying
davecee's Avatar
This is the most likely cause.

http://www.nbcnews.com/storyline/mis...ng-777s-n50591
Mar 12, 2014, 07:01 PM
It's gonna be YUGE!!!
LVsoaring's Avatar
Quote:
Originally Posted by AustinTatious
Just a random thought, pure speculation here.

Many aircraft have an "EDM". Or "Emergency Decent Mode"

In the aircraft I fly, when activated due to a loss of cabin pressure the autopilot will make a 90 degree turn to the left and the autothrottles will bring the engines to idle ans start a max decent to 15000 feet..

It is possible they had a dual engine failure and lost pressurization due to the absence of incoming bleed air.

They could have got their mask on or possibly passed out. You have to manually switch you mic selector to oxy mask in order to continue to communicate. It is possible they forgot to do this while they were busy trying to relight engines. It is also possible they were unconcious.

Had they been unconcious if they regained conciousness at low altitude they may have been out of VHF range so no calls would have been heard except by other airborn traffic on that frequency.

It is also possible that if both engines did flame out that the did not fully regain conciousness when the autopilot leveled off which would have no doubt resulted in a stall (since the engines were dead.)

This would account for the turn to the left, the lack of radio calls AND debris being found near the expected route.

Just speculation.
If they had a dual engine failure, the airplane would not immediately depressurize.... it would take some time. Certainly enough time for the crew to don the masks and get the O2 flowing before LOC. They could also start the APU (assuming it wasn't on MEL), and get electrical power and air to run the A/C & pressurization system, whilst they attempted relights. (Also with the aid of APU air) (I do not know whether the 777 APU can be operated up to cruise altitude) Edit.... found it....

777 Flight Crew Operations Manual
Engines, APU
Chapter 7
APU System Description
Section 30
December 13, 2010 D
632W001-EAD 7.30.1
30 – APU System Description
APU System Description
Introduction
The auxiliary power unit (APU) is a self–contained gas turbine engine located in the airplane tail cone.The APU can be started and operated to the airplane maximum certified altitude. The APU supplies bleed air and electrical power. Electrical power has priority
over bleed air. Electrical power is available throughout the airplane operating envelope. Bleed air is available at or below 22,000 feet.

Entire 777 FCOM available here

The more I read about this (and of course, who knows how much is accurate and reliable?), the more I am thinking the disappearance was a deliberate act. I say "disappearance" because in all actuality, we don't even know if the airplane crashed or not.
Last edited by LVsoaring; Mar 12, 2014 at 07:19 PM.
Mar 12, 2014, 07:03 PM
It's gonna be YUGE!!!
LVsoaring's Avatar
Quote:
Originally Posted by davecee
On what do you base the claim that that is the most likely cause?
Mar 12, 2014, 07:04 PM
Registered User
Big Foot 48's Avatar
An former NTSB expert just said he thought it was likely caused by explosive decompression at 37,000 feet. Boeing had issued an alert sometime in the past about cracking around a rear antenna that could have caused such an event, apparently. (Davecee's link above I think)
Mar 12, 2014, 07:26 PM
It's gonna be YUGE!!!
LVsoaring's Avatar
Explosive decompression would have ripped the airplane apart at cruise speed. There would be an enormous debris field with thousands upon thousands of floating bits. The airplane's intended track was surely the first place searched, no such debris field was found. So I think that scenario is unlikely.

TWA 800 left a 10-mile long debris field, and it was only about 13000 feet when it came apart.
Mar 12, 2014, 08:24 PM
Registered User
I'm really surprised an NTSB "expert" would think that.

I'd expect to get huge chunks of floating stuff over a huge area if it broke up at altitude. A nose in dive while in one piece would get most of the plane underwater in a hurry and possibly minimise the number of areas that would be able to hold air for something to float back up?
Mar 12, 2014, 08:30 PM
Suspended Account
The Air France Airbus went down because of sensor malfunction feeding the auto and the pilots the wrong information.
Could it be that they tried to ditch the plane and because of it the very large debrie on the sat pics.
Speculation
Mar 12, 2014, 08:50 PM
Registered User
Do they have it?

http://www.theguardian.com/world/blo...a-live-updates
Mar 12, 2014, 09:02 PM
AustinTatious
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Quote:
Originally Posted by BE77 Pilot
Pretty good thinking. Why the initial 90 degree left turn by the autopilot?
I'm not sure why they do a 90 degree turn... Usually a turn is SOP for an emergency decent so that you don't go down on top of someone below you on the same airway, however most just turn 45 degrees.
Mar 12, 2014, 09:08 PM
AustinTatious
AustinTatious's Avatar
Quote:
Originally Posted by LVsoaring
If they had a dual engine failure, the airplane would not immediately depressurize.... it would take some time. Certainly enough time for the crew to don the masks and get the O2 flowing before LOC. They could also start the APU (assuming it wasn't on MEL), and get electrical power and air to run the A/C & pressurization system, whilst they attempted relights. (Also with the aid of APU air) (I do not know whether the 777 APU can be operated up to cruise altitude) Edit.... found it....

777 Flight Crew Operations Manual
Engines, APU
Chapter 7
APU System Description
Section 30
December 13, 2010 D
632W001-EAD 7.30.1
30 – APU System Description
APU System Description
Introduction
The auxiliary power unit (APU) is a self–contained gas turbine engine located in the airplane tail cone.The APU can be started and operated to the airplane maximum certified altitude. The APU supplies bleed air and electrical power. Electrical power has priority
over bleed air. Electrical power is available throughout the airplane operating envelope. Bleed air is available at or below 22,000 feet.

Entire 777 FCOM available here

The more I read about this (and of course, who knows how much is accurate and reliable?), the more I am thinking the disappearance was a deliberate act. I say "disappearance" because in all actuality, we don't even know if the airplane crashed or not.
The speed of the decompression would depend on on how tight the airframe was. You are likely right however.

On the APU, If the engines flamed out because of contaminated fuel, then it may not have started.

As I said, wild speculation...
Mar 12, 2014, 10:21 PM
AustinTatious
AustinTatious's Avatar
Hope it doesnt turn out like this

http://www.airspacemag.com/history-o...371187/?no-ist
Mar 13, 2014, 12:36 AM
I'd rather be Flying
davecee's Avatar
Quote:
Originally Posted by LVsoaring
On what do you base the claim that that is the most likely cause?
read the link.It's the only scenario that contains more than speculation




A cracking and corrosion problem on Boeing 777s that could lead to the mid-air break-up of the aircraft prompted a warning from air safety regulators weeks before the disappearance of Malaysia Airlines Flight 370, federal records show.


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