E.N.T.

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I'm sorry if I'm not as educated as you in aviation physiology.
I'm just an ear, nose and throat doctor who likes rc jet flying.
It was just my humble opinion as to medical physiology.
Anyway, thanks for teaching me as to these aviation aspects.
It's just kind of learning a little bit more each day, after 30 years in
practice.


E.N.T.

eddieC

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They grounded the fleet for 4 months last year over this issue, looks like nothing was fixed. For the pilots to refuse to fly is very significant. The ramifications from disobeying orders and career impact should speak for itself.

Just to be clear, this isn't based on one or two incidents, but at least 11 cases. One involved a local boy who died during night training, and people here are watching this with great interest.

Now that made me laugh out loud there!   

ec121

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I went hypoxic in the chamber. If it happens and you don't have an early warning system of some sort, you will never know what happened.

NickC5FE

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My extremities got pins and needles so bad they felt like they were burning on fire in the chamber

dbsonic

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I was just saying they've done this before. They know or should be able to draw from so many years of experience and research. Hopefully we havent lost the edge.
But with so many things, it sounds like it may not be so easy if there is a fundamental issue extracting oxygen from the compressor stage.
Todays breathing systems are so advanced and even able to detect apnea and warn you about it. In a similar vein, surely we can detect when a pilot is unconscious and either automatically provide emergency o2 or get plane into auto pilot so it doesnt pile in...but this is just a band-aid solution and not feasbile for combat.

I_Fly

Does anyone remember Oxygen bars a decade or so back.   You paid to get in an breath O2.  I'm not sure what concentration and have never been to one.   I do remember them being advertised 10-15 years ago.   Seems to me that any significant risk would have prevented such a crazy fad. 

tp777fo

My Feedback: (28)

I get a warm happy drunk feeling. Thats why we did the chamber....to recognize your hypoxia symptoms.

Couch Potato

Breathing pure oxygen didn't do this guy any harm.................[:-]

merlin51

Hi all
F-18 has same o2 system and same problem, lost 18 planes to date and Navy can't find the problem in Hornet. F-22 has been requested for combat, but the secretary of defense won't release for combat.

ec121

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Thinking back to the part I remember, I think my legs got sort of numb and tingly. Then I got the twitches when my partner put my mask on.

FalconWings

My Feedback: (57)

OBOGS is not fed Bleed Air.
Bleed Air NEVER comes into contact with ECS. Bleed air is only used to run the Air Cycler, which compresses outside air for a number of utility reasons.

Bleed is also used wherever a heat source is needed, via multiple Heat Exchanger phases.

I worked in the design the Block 50/60 F-16 OBOGS system.

David

AndyAndrews

I'd like to hear Bucks (Yeahbaby) viewpoint on this. He flew F-18s.

David Gladwin

RAF aeromedical training takes pilots to 48 k in the chamber to demonstrate use of pressure demand equipment. (100% oxygen under pressure with the mask toggle down clamping it hard against the face , requiring effort to breath OUT) We also got VERY thorough hypoxia training, the onsets of which CAN be identified with such excellent training. Going higher than 48k ( partly pressurised, 25 K cabin altitude ) as we regularly did in Canberras and Victors (the Lightning guys went WAY higher than that even after pressure helmets were abandoned, high enough for one guy on 74 in Singapore to intercept U2 from ABOVE!) would create problems if pressurisation was lost. We all survived.

Dbsonic, going above 25 k unpressurised, is no big deal and even at my age, going to 20 k in a sailplane using a canula (wave soaring in NZ) was no problem, just b.... cold ! As instructors we used to do upto 3 trips a day on JP4s (only the JP5 was pressurised) going to 35 k unpressurised, with the airmix system progressively increasing O2 content to 100 % Just didn't eat baked beans or a curry beforehand ! Concorde , cruising at upto 60k had a very good O2 system but being pressurised to only 6k gave reasonable time to establish an emergency descent if a window or windscreen blew out, never happened.

Use of 100% oxygen is routine in many military aircraft and 100% is set for emergency use (cockpit smoke, depressurisation) on airliners.

and Nick, the bailout bottle is automatically triggered on ejection but can also be used as a standby O2 system in the event of a problem with the primary and the RAF considered it as exactly that. Martin- Baker seats have a manual O2 activation toggle on the left of the seat pan, yellow and black spherical knob. Only about 10 mins supply but enough to get you down to 10k.

Still very disappointing to hear that an aircraft as sophisticated and as incredibly expensive as an F22 can't get the oxygen system right, surely one of the easy bits ! Lets hope the F35 is better !


David Gladwin.

basimpsn

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Was this guy flying a F22 ?

http://www.youtube.com/watch?v=_IqWal_EmBg

VF84sluggo

My Feedback: (55)

The onboard O2 systems in the Navy jets I flew were all suppiled by the round green LOX bottles. Pure 100% O2 delivered. As a student, the O2 mask was required to be worn from start-up to shutdown. In the fleet it was (supposed) to be worn from takeoff to landing when ashore, and pretty much all the time for carrier ops.

Didn't cause me any harm........I think

Harley Condra

My Feedback: (4)

Kalitta 66? If it was Kalitta Air, he was flying a 747 freighter.
See www.kalittaair.com for a list of their aircraft. Ypsilant Michigan, the destination of the hypoxic pilot is home base for Kalitta Air.
Kalitta Air is owned 100% by Conrad (Connie) Kalitta, ex NHRA Top Fuel owner/driver. He used to be called "The Bounty Hunter". He drove the first fuel car to top 200 MPH in an NHRA event.
He lost his son Scott in a Top Fuel crash in 1998.

grbaker

My Feedback: (29)

And Beau Bridges played him in the movie Heart Like a Wheel

jpjamie

VF84sluggo: did your mouth got a bit dry from the 100% oxygen? Were there heated humidifiers in the jets? Wasn't that oxygen a bit cold? As you said breathing 100% oxygen will not cause death, besides being extremely dry and (unless humidified and heated) it's cold and just not the best gas to breath for very long periods of time.

Nitrogen takes up most, I say most because there are other gases "partially" (reference to the gas laws) in the atmosphere we all breath. Nitrogen expands our lungs and unless we are exposed to high pressure (deep scuba diving), it doesn't enter our blood. Nitrogen expands your lungs allowing oxygen to diffuse from our lungs into our blood where it's absorbed by hemoglobin in the red blood cell. When we breath 100% oxygen for extended periods of time, our lungs contract a bit from the lack of nitrogen, but this usually isn't much of a problem.

This has everything to do with why we breath 21% oxygen at sea level AND at 35,000 feet. Yes, there is 21% oxygen at 35,000 feet, but we would all die breathing it. It's all about the partial pressure of oxygen in the atmosphere and the partial pressure of oxygen (blood gases) in our blood. I'll let you read about that instead of getting into ALL that here.

You may have recently watched an Air Force general talking about pilots wearing pulse oximeters on CNN. Pulse oximeters actually measure the red color from the hemoglobin and report it as a saturation which is normally 98%. Pulse oximeters can have an error (they are getting better) of + or - 3% which is why they are used mostly as a trending device. The trouble just starts when the saturation of hemoglobin is 90% and especially BELOW 90%.

ANY pilots (especially carrier jet jocks landing at night!) needs to be fully saturated at all times at or around 98%. This is why airliner cockpits have cool black "fighter jock" oxygen masks behind and above the pilots, not those silly drop down yellow thingies in coach! No matter how good any pilot THINKS he is, he/she IS going to start getting conthoroughly fused especially at hemoglobin saturation at or below 90%. Forget dog fighting!! This is exactly why oxygen is worn and is so very important.

As for the F-22 I'm not sure how the on board oxygen is supplied. Oxygen can be supplied from pressurized cylinders holding 100% oxygen at 2,200 PSI. The pressure is usually stepped down to 50PSI for fluidic control of oxygen breathing devices. Oxygen can also be supplied by fractional distillation of air, but the supply of 100% oxygen (depending on the device) is much more limited this way. I suspect the F-22's jet engines may supply compressed air at high pressure levels to an on board fractional distillation unit that may be supplying a higher volume of 100% oxygen.

This is pure conjecture, but the issue may be contamination from the compressed "air" coming from the jet engines causing a transient condition called methemoglobinemia.

gunradd

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I know you could always tell you had a compressor seal going bad on the planes I worked on because the airplane would smell so bad as soon as the bleed wad air was turned on.

FalconWings

My Feedback: (57)

That is an issue at one of the Heat Exchanger/Trim Air interfaces and could be serious.
Which compressor are you talking about?

David

eddieC

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Not in this case. Kalitta has operated many different types over the years. Kalitta 66 was a DC-8. They lost pressure due to an improperly installed exit hatch after maintenance. The crew were very fortunate to survive, although the captain was hospitalized with serious injuries.

http://www.fss.aero/accident-reports...report_key=975

A few years ago, one of Connie's 747's left an engine in Lake Michigan. Let's just say they've had an - interesting - operation. One of my buds retired from a Connie 747 job a few years ago.

gunradd

My Feedback: (9)

It was the compressor section of the engine. Both citations and the old hawkers used engine bleed air for the airconditioning/heat and pressurization.. Yes they had heat exchangers but that was just to cool the bleed air.

OldFart1

Yep, old (non -400) 747's. Have one on the south ramp currently (charter air side of LAX). They transport lots of horses - typically through the AOA gate next to my office. Fun to watch unless the wind is from the East

eddieC

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Connie actually operates 6 -400's, 1 -100, and 16 [X(] -200's. I believe all have been converted to dual-crew, eliminating the flight engineer position. All the -400's were ex-JAL, IIRC.
They had a 727 kept at LEX (Lexington, KY) just to run horses to the Mideast when 9/11 occurred. It was one of the 'phantom' aircraft that flew during the three days all aircraft were stopped post-9/11. One of his 747's was also used. Despite the media spin, those flights definitely happened.

http://www.kalittaair.com/aircraft.aspx

flycatch

My Feedback: (26)

I never worked on an oxygen system but did repair avionics while in the military. We had a problem once on one particular aircraft that took over four months to resolve and it came down to a male connector in a wiring harness. I make mention of this only because it takes time and sometime luck to find the root of a malfunction. The problem was caused by a factory installed assembly that for some reason worked intermittenly. I believe this is happening with the oxygen system. The military is not in the habit of putting your life or their hardware in harms way. It is just to costly to say otherwise.