F-22 Raptor “smoking gun” not found

F-22 Raptor “smoking gun” not found

Air Force leaders still do not know for sure why the F-22 Raptor keeps suffocating its pilots after the service completed a fleet-wide study of its aircraft oxygen generation systems.

Air Force engineers didn’t find a “smoking gun” during the Air Force Scientific Advisory Board’s quick-look study, said Lt. Gen. Herbert “Hawk” Carlisle, the Air Force deputy chief of staff for Operations, Plans and Requirements.  Air Force Secretary Michael Donley ordered the study after the service grounded its F-22 fleet when multiple pilots experienced “hypoxia-like” symptoms in flight.

An F-22 pilot crashed and died in November. An Accident Investigation Board found the fighter jet’s bleed air intakes malfunctioned and Capt. Jeffrey Haney “most likely experienced a sense similar to suffocation.” However, the AIB’s controversial report blamed the pilot, not the aircraft for the crash. The Defense Department’s Inspector General is completing an assessment of that report.

Air Force Scientific Advisory Board found that a “couple of contributing factors” to include a leaky cooling system has restricting oxygen reaching pilots, Carlisle said on Tuesday. He didn’t want to list it as the “smoking gun” because service engineers do not know for sure how the fluid from the cooling system got into the F-22’s On Board Oxygen Generating System (OBOGS).

Engineers also found problems with the F-22’s breathing regulator/anti-G valve, better known as the BRAG valve, Carlisle said. The BRAG valve connects the OBOGS to the pilot’s oxygen mask.

When there is a problem, F-22 pilots also do not receive “indications and warnings” fast enough in “fleeting cases”, Carlisle said.

The Air Force three-star said the problems with the oxygen system do not just affect the F-22. Engineers found similar problems in the Navy’s F-18. The Air Force has shared results of their quick look study with Navy leaders.

The quick-look study inspected the oxygen generation systems of the A-10 Thunderbolt II, F-15E Strike Eagle, F-16 Fighting Falcon, F-35 Joint Strike Fighter, B-1 Lancer, B-2 Spirit, CV-22 Osprey, and T-6 Texan II as well as the F-22.

Air Force officials will inspect the F-22’s emergency oxygen system analyzing how it’s used and what “it takes to deploy it,” Carlisle said.

The service will continue to study each case in which F-22 pilots experience hypoxia-like symptoms. A special team continues to inspect the problem, Carlisle said.

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Get it fixed! nuff said

The solution is so obvious… just get rid of that over-priced, delaminating canopy, and let the ace flyboys’ sexy white silk scarves fly free in the breeze!


We had a simple system with a bottle of oxygen back when — then they made the system complex and it doesn’t work.

There is a saying “keep it simple stupid” — go back to the old system.

In the least, it make for a simple temporary back to work fix until they can actually fix that system.

Has anyone calculated the % of flights where F-22 pilots experience hypoxia symptoms? might be nice to know if this is a rare or regular occurrence.

Servicing O2 bottles decreases sortie regeneration time, You have to make some “choices” when you spec in signature reduction and then spec “rates” for generating “sorties.” You wouldn’t try to fly the contraption with cable & quadrant flight controls. The KISS principle works pretty well on your Cessna 172 — not so well on a platform that has to supercruise and uses thrust vectoring to perform high-dgree AoA manuvers. Hopefully, the fix doesn’t mean derating the engine. I believe the problem is solve-able since the F-16 has an OBOGGS solution — but the propulsion system is vintage 1970s design.

Best way to six this is modify the F-15Cs Oxygen system and put it in the F-22. Overall they way the F-22’s problems are going this may kill the F-22 and that’s NOT a good thing.

Well seeing how it was not designed to use a bottle, you have to make one fit some place. That is not a simple Mac Guyver fix.

The system the F-22 has is pretty much stolen out of the F-16 as it is. I can’t imagine what they did to screw it up.

That takes time & may mean moving stuff around. You just can’t do like the A-team used to do and slap something together.

Sounds like they did an inadequate job during developmental testing and poor tech oversight. The program management probably got promoted and eventually retired to high paying jobs at Lockheed.

When will we ever learn?

Well I bet I know what it is. If the ECS system is anything like supers it run the radar cooling system through the ECS intercoolers. Now I saw one crack and dump fluid into the system. Pilot had same type symptoms etc. He had the presence of mind to pull the green apple and have fresh O2.

And once again, America’s premier cutting-edge $400M hangar queens are grounded…

i like f 22 raptor

You’re pretty funny. And I bet you spend a lot more time making your spiel at the comedy club than you do at 50,000 ft wondering whether that woozy feeling that’s come over you is gonna be your last.

Talk about armchair aces…

And even worst, the f-35 is said to have an OBOG based on the same compact design. And regardless whether the cause is from incompetent or that they pushed the limits of the knowledge, it fails as it’s a life support system.

And one have to do an apoxia test in order to understand what it is about and that when they say it is vicious, it is really vicious. While I am not a pilot, I had to do this test and I was asthounded by the results. The truth is that you don’t fell it because you don’t loose all the air at once, in many instance there is little to zero signal from the body, that where a training can make a difference.

An optimist could say that this OBOG have been optimized to death. :-)

I was told when I was in Navy flight training in 1966 that no matter what happens and you crash, that the accident board will say it is pilot error. If the aircraft is at fault, they have to ground the aircraft until they find what is wrong and fix the problem. It is so much easier just to say it was pilot error. Dead pilots do cause many problems. Simply replace him and hope it doesn’t happen again. I guess not much has changed in the last 45 years.

The F-22 is a disaster. Only the JSF catastrophe makes it look good.

I’d try looking into how they are cleaning the masks and ancillary equipment. Unapproved cleaners can degrade the “rubber” components, releasing minor amounts of toxic vapors. When enough is breathed, black-out. If “rubber” gaskets are used in all the alphabet-soup system components, degredation can also allow unintended bypass. Just my ground pounder thoughts. Gas masks seem to have the same type problem over time.

Chinese software virus in OBOGS. Probably waits for airplane status set to “mission” before it activates.

Maybe it’s a good thing they didn’t make too many of these things.


TO bad cost over rides an poor management small problems can hurt the military stop the wast1

Sure it’s been optimised, the F-22 OBOGS is the best performing Lockheed design by profit per unit sold.

Except Honeywell makes the OBOGS, not Lockheed.

What a thought… bringing down and/or delaying developing systems in non-kinetic fashion by exploiting our short-sighted focus on cost and schedule to the detriment of performance capability…

The AF has become more of a PR firm that a combatant arm over the last 30 – 40 years. It starts with the Chief of Staff and goes downhill from there. Harsh? You betcha! But, if the AF cannot be harsh on itself who will?

The F-22 program became a poster child of the AF’s PR firm mentality. Corners were cut to meet promotion board schedules.


If the AF’s material and development command ever lived up to the following: Projects delivered on time? Projects delivered at or below costs? Projects delivered with the required operational capabilities? How about any two of the three (66% success rate)? How about any one of the three (33% success rate)?

Yet, how many commanders, program mangers, sub-system program managers, bits and pieces managers have been promoted since the 1980’s (era of the B-2 and F-22 programs) when they failed to accomplish their primary duties?

BTW, did almost 12 years in a section of the AF’s test and development community after retiring with 18 years combat aircrew duties. So my views are based on long term personal experience.

Just letting my silk scarf fly in the breeze

How is it a disaster? The F-18 had the same issue with OBOGs. Suddenly officials ‘don’t remember’ that time and period.

Every new plane has problems, all the way back to the A-36 Apache becoming the P-51 Mustang.

I have often wondered if it’s the actual filtration system of the OBOGS itself slowly breaking down and causing the contaminiation in the life support system.

Touché, my court-eous friend… ;o)

A big question: is the F-22 ready to be used for strikes on Iran, if called upon? There are only 20 B-2 stealth bombers and the F-117 stealth fighters have been retired, so the 120+ F-22s are the only unclassified stealth aircraft available for strike and air superiority in contested airspace.

The F-18 did not have the same issue with the OBOG. The F-18 had an issue with its OBOG, which have been easilly identified and corrected by relocating some components (I think it was the exaust getting inside the system).

The F-22 have a problem of its kind. Nobody know where it come from, pilots have to pass blood tests after every flights, they installed more filters and more sensors and according to this article, the problem is everything except solved.

Since the problem seems to be so hard to find, I suspect may be a pure chemistry problem but I could be wrong. Anyway this is a life-support system and as such it have failed.

JRL… let’s dial back the exaggeration… It says in the blog post you linked that it was a 1 day stand down, not a grounding of the fleet. Same thing happened at Langley last year. Same thing happens at any base when the commander, for whatever reason, feels the need for it. I saw this first hand at Barksdale when a maintenance troop didn’t properly chock his vehicle and it rolled close to a parked aircraft before it was stopped. Commander shut down all operations the next day for a safety stand down.

I worked on F-16’s when they were fairly new. They had an early problem. For some unknown reason planes were plowing into the ground. First they said the pilot committed suicide, then blamed maintenance. I don’t know how many crashed but the entire fleet was grounded. The real problem was known but was glazed over in a training video to check a wire bundle for chaffing.when doing other work. What was happening the wires would chaff causing the ADI to indicate inverted flight. They would fly into clouds flying inverted the altimeter shows he’s losing altitude, get’s low altitude warning pulls back on the stick hits afterburner. One spouse sued General Dynamics and then the truth came out. They made a movie about it called Afterburn. I was at the base when her husband was killed. He wasn’t the only one.

This was what I was alluding to. The F-18’s OBOGS was an issue, though not exactly identical to the Raptor. There are F-22s hops on a daily basis and I seriously question how many occurences have happened. None reported in the news lately. However, I almost wonder if a certain production run of Raptors were affected rather than all of them.

I completely agree with you on the chemistry of it. I did hear that Honeywell changed from sodium ions to lithium ions to enhance filtration. The chemistry part is the key to the solution of the issue once and for all.

For the fact that we don’t ear anything in the news by now, it may well be a strict consing to the pilots and since they are in low count, it is easier to keep it secret. There is a good gap between this article and the others, it must mean that the problem still exist and still concretely happen, and perhaps less often due to a more careful maintenance, or perhaps those filters are not in vain.

OBOS + Software + High Performance Requrements = POSSIBLE Hypoxia.
These systems were tested well into the dirt by LM during and after EMD. The systems there used require a LOT of maintenance, and there is a LOT of systems interaction that could cause this type of problem.
NOT an easy A10 type fix.
F22 is the best bird out there. The LM Engineers will find and fix this. Have a bit of faith in the workings of the Loggies and Maintenance pukes. Best not to trash a viable program due to 1 problem.

To whom it may concern (Environmental s Life Support) For the F-22… 1.Has anyone looked into the Oxygen line fittings? Which can contract during temperature drops during flight maneuvers? Thus causing the seal to contract during the ACFT maneuvers causing the the fitting to Leak and Freeze Up… Thus pilot HYPOXIA!!! When ACFT returns Seals seem to be back to normal operation, cause O2 lines and fittings had time to defrost by then(back to Base). 2. At times Manufactures have mistakenly changed the way they make fittings for Cost Efficiency, Using Different Material etc… 3.And how about Rapping-Up the O2 Lines and fittings in Refrigeration Insulation… “Temporary QUICK FIX” Sincerely

As an F22 crew chief, I know for a fact that it is on rare occasion that the pilots experience these symptoms. While it may be be unresolved, the new filters the pilots use have been working quite well. My only concern is for the 7-levels who do engine runs and have experienced the same symptoms. What is the command doing for them?

Frustrating to read about the F-22 problems. The hornet and superhhornet community continues to battle a rash of hypoxia issues, many of them “unexplained” which results in lower confidence of those of us flying them. Frankly, never had an issue in LOX models, and only have had issues with OBOGS. The system has proven to be unreliable. There should not be incidents happening on a monthly basis or more. With that being the case, obviously there are major design/implementation flaws. At the least, oxygen monitors should immediately be implemented since the onboard monitors have failed in several cases or simply don’t show when there is a problem. And obviously this won’t happen because that = $$$. Absolutely UNSAT.
–Hornet pilot

Kitahara.…..wrong on seal issue. This is a gaseous issue…not liquid. The freezing you speak of would have to be –297F. At altitude maybe 60 below. This system gets air from conditioning system and OBOGS purifies the air into breathing oxygen. Now being a former 22 troop I would speculate either the OBOGS UNIT or Above mentioned BRAG valve are main issues. I would look at cooling heat exchangers as a possibility as well. The coolant used for equipment cooling and air conditioning share some of the heat exchangers. Just my.02

Some pilots refuse to fly F-22 Raptor amid jet’s oxygen problems -

“…Air Force pilots have complained of hypoxia-like symptoms while flying the F-22, the world’s most expensive fighter jet. Refusal to fly can bring a reprimand and even discharge from the Air Force…”

Some pilots refuse to fly F-22 Raptor amid jet’s oxygen problems — http://​www​.latimes​.com/​b​u​s​i​n​e​s​s​/​l​a​-​f​i​-​f​i​g​h​t​e​r​-​pil

“…Air Force pilots have complained of hypoxia-like symptoms while flying the F-22, the world’s most expensive fighter jet. Refusal to fly can bring a reprimand and even discharge from the Air Force…”

The F22 is a work of art. General Carlisle is extremely intelligent. An answer will be found.
Perhaps there is a problem with OBOG sensors, switches at high altitudes and G-forces.
I like the contribution about O2 fittings as this is sometimes overlooked. Either way, the problem will be found or a solution to the problem will be created.
Go Air Force!

About fifty years ago, Germany was having a problem with its new F104 fighters — They were continually plowing into the ground, while the same aircraft in the USAF was not.
The problem was eventually traced to the use of clorinated solvent to clean the oxygen system in routine maintenance between flights (residue acted as an anesthetic)
No actual oxygen deficiency
Has this been considered?

I think you are on to something, I am of the opinion that an icing problem may be one of the reasons for this condition.

With reports of mechanics getting ill on ground pressurization turns, I tend to believe there are leaks allowing jet exhaust into the cockpit. Whether is through the OBOGS, a faulty bleed air duct or canopy leak…I dont know. There is no need for oxygen on ground turns or below 10K, so I would almost rule out the OBOGS. Hypoxia symptoms can be caused by carbon monoxide as well.

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