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Posted

...I'm an E-3 Sentry flight engineer...

 

I had to google E-3 sentry, as soon as I saw the photo I exclaimed..!aah AWACS ! Airborne Warning and Control Systems. You obviously know your beans fellah ! :smartass:

 

Simfreak, your anonymity is fine by me. :smoke:

 

Thanks for your help on here guys !

There are old pilots, there are bold pilots, but there are no old, bold pilots.

Posted
About that...

Knew a guy in that flight. Its been 5 years and 3 months or so and the case is still in court (in fact the judge just denied witnesses from Boeing and some other European organization, don't know too much details on it).

 

And thats how it somehow happened....

"The preliminary investigation reports state that the maintenance performed on the aircraft had left the pressurization control on a 'manual' setting, in which the aircraft would not pressurise automatically on ascending; the pre-takeoff check had not disclosed nor corrected this. As the aircraft passed 10,000 feet (3,000 m), the cabin altitude alert horn sounded. The horn also sounds if the aircraft is not properly set for take off, e.g. flaps not set, and thus it was assumed to be a false warning. The aircrew found a lack of a common language and inadequate English a hindrance in solving the problem. The aircrew called maintenance to ask how to disable the horn, and were told where to find the circuit-breaker. The pilot left his seat to see to the circuit breaker and both aircrew lost consciousness shortly afterwards."

 

Poor people didn't know what hit them. :(

 

It was an outflow valve that was left open in the manual position after ground maintenance. The flight crew should have checked it and didn't. (allegedly)

http://www.moi.gov.cy/moi/pio/pio.nsf/All/F15FBD7320037284C2257204002B6243/$file/FINAL%20REPORT%205B-DBY.pdf

Posted

When you do your walkround prior to flight the outflow valves are in the fully open position. The outflow valves dont usually close until the aircraft passes a certain speed during the take-off roll or when the weight on wheels switch activates indicating aircraft is airborne.

 

As for the checklists on the 737 in question when airborne regarding outflow valve/pressurisation checks ... Í dont know. Need a 737 driver..

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Posted

The outflow Valves can sometimes not be seen via a visual walkaround. I am a prior C141B Flight engineer and on that plane our outflow Valves were controlled by a Pneumatic relay via our control or touchdown switches. Their position was never checked visually as a preflight duty. Both because of location and type. However we could tell pretty quick on climbout that Cabin press. was with the aircrafts altitude by looking at our diff pressure gauge or by how it felt. Especially through 8,000 feet and up.

Posted

Sure, but we were talking about the B737 and not a c141b.

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Posted
As for the checklists on the 737 in question when airborne regarding outflow valve/pressurisation checks ... Í dont know. Need a 737 driver..

 

Ex. 737 here... From what I remember there's no such thing in the checklist (other than the expanded checklist which basically covers _every_switch). The actual switch is easy to miss during your scan-flow. It is usually in "auto". No need to touch it unless you have pressurization problems in-flight. To be perfectly honest... I didn't check it's position every single time I did _my_ scan. Tragic accident but this could've happened to anybody.

"It's not the years, honey. It's the mileage..."

Posted

Like most accidents, it had multiple contributory factors:

 

Engineer leaving the switch in manual.

Crew not checking it

Crew not reacting in the correct way to the pressurization warnings

Flight attendants not contacting the cockpit when the emergency oxy was deployed

 

All in all very sad, but unfortunately fairly common.

Posted

Hypoxia, to be simple, is as sayd the lack of oxygen on the hemacia (red blood cell), it can be generated as discussed by lack of oxygen on a plane but also as a medical condition.

People with lung problem (Asma in one of them) depending on the severity are prone to this. Unsually there s 2 exits: the lvl of hypoxia can grow fast and the person will shut down (faint) from lack of oxygen on the brain, or remain stable in a certain lvl and the person will not loose consciousness and will waste her energy slowly just trying to breath until full exhaustion.

At the shut down point there s 2 possibilities, assuming no help comes:

1) The strenght of the unconscious person is enought to supply oxygen to the vital organ, and this person will probably wake up, or,

2) death will ensue because the fainted person can t give the required strenght to your lung to bring in enought oxygen to suplply vital organs, even unconsconcious, but then you feel nothing so its welcome, to say the true you pray to faint after a certain level and time of pain.

 

The sympton are very well described. I dont know about plane hypoxia, but i suffered hypoxia from medical conditions 2 or 3 times when i was grown enought to remember and there s nothing pleasant to it. My personnal record was something like 14 hours, i actually fainted various time with my parents waking me up to be sure i would breath properly.

 

Usuall sympton are dificult breathing, constant headhache as your braincells die from lack of oxygen, discolored or blue nails and lips, finger tingling, abundant sweat as you fight with your lung to supply oxigen, and cold, sometimes blurred vision as your near faint.

I find it strange that in some cases hypoxia gives no pain, probably the same as slowly cooking a toad, it doesn tfeel anything till its too late. Medical hypoxia is another game. Would it be a simple faint-and-die, it would be a welcomed sweet death.

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Posted

It's part of my preflight to check the outflow valves. I do this by checking the switch action on the pressure controller, the outflow valve in the forward lower lobe, the same one on the exterior walk-around, and the aft valve on the exterior.

 

The valves are left open on the ground and close upon rotate.

Posted
Like most accidents, it had multiple contributory factors:

 

Engineer leaving the switch in manual.

Crew not checking it

Crew not reacting in the correct way to the pressurization warnings

Flight attendants not contacting the cockpit when the emergency oxy was deployed

 

All in all very sad, but unfortunately fairly common.

 

If nobody went alive from the flight, how to know the crew wasn t "off" when the mask went down? It s seem always a bit unfair to blame the dead, and easy since they are not present to defend themselves.

Did the pilots or crew ever went an airchamber training to know the effect of hypoxia ?

Did the warning set up at the right time or too late ?

it doesnt take much from: be able to do something and: not being able to do something when we treat altitude induced hypoxia, crediting all what is testimonied here.

 

As for altitude pressurization, maybe its me, but apart from the damn cold and gas realease present on a skydiver airplane, i don t feel much diference on the pressure at 12000 feets. Maybe the adrenaline too.

 

Since liners are heated, it may very well be that the crew never felt anything until too late, and since so many thing are auto it maybe a a simple malfunction for whatever reason god know.

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Track IR 5, Hall sensed Cougar, Hall sensed TM RCS TM Warthog(2283), TM MFD, Saitek pro combat rudder, Cougar MFD.

Posted

-The masks depending on aircraft type usually drop between 10,000ft and 13,000 ft well before the crew would have become hypoxic.

-Majority of Civilian pilots do not do Pressure chamber runs.

 

I posted a link earlier to the accident report, if you are interested read it. All of your questions will be answered.

 

There is a moral to it all though 'DON'T ASSUME... CHECK'. That was drilled into my forehead during military training.

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Posted
If nobody went alive from the flight, how to know the crew wasn t "off" when the mask went down? It s seem always a bit unfair to blame the dead, and easy since they are not present to defend themselves.

Did the pilots or crew ever went an airchamber training to know the effect of hypoxia ?

Did the warning set up at the right time or too late ?

it doesnt take much from: be able to do something and: not being able to do something when we treat altitude induced hypoxia, crediting all what is testimonied here.

 

As for altitude pressurization, maybe its me, but apart from the damn cold and gas realease present on a skydiver airplane, i don t feel much diference on the pressure at 12000 feets. Maybe the adrenaline too.

 

Since liners are heated, it may very well be that the crew never felt anything until too late, and since so many thing are auto it maybe a a simple malfunction for whatever reason god know.

 

Read the report...... It tells you everything you need to know. And ultimately, yes the crew did screw up. They crew were human, just like the passengers. Humans screw up every now and again.

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