U.S. Tried Halting Pakistan Nuclear Drive: Documents

WASHINGTON - The United States waged a secret diplomatic campaign in the 1970s to prevent Pakistan from developing nuclear weapons by pressing countries to control exports, declassified documents said.

In remarks with striking parallels to current U.S. debates, officials in President Jimmy Carter's administration voiced fear about Pakistan's trajectory and tried both pressure and aid incentives to seek a change in its behavior.

In a secret November 1978 memo, then-Secretary of State Cyrus Vance instructed U.S. diplomats in Western Europe, Australia, Canada and Japan to warn governments that Pakistan or its covert agents were seeking nuclear material.

Vance acknowledged that Pakistan was motivated by concerns over historic rival India. But he voiced alarm that Zulfikar Ali Bhutto, before being deposed as prime minister in a coup, said that Pakistan would share nuclear weapons around the Islamic world.

"We believe it is critical to stability in the region and to our non-proliferation objectives to inhibit Pakistan from moving closer to the threshold of nuclear explosive capability," Vance wrote, the year before the overthrow of Iran's pro-Western shah and the Soviet invasion of Afghanistan.

Britain was waging a parallel campaign, Vance said. Britain banned the export of inverters - which can be used in centrifuges that produce highly enriched uranium - and urged other countries to follow suit, Vance said.

Most countries sounded sympathetic, though West Germany - a major industrial exporter - insisted it already had adequate safeguards, memos said.

Pakistan nonetheless pursued nuclear weapons and detonated a bomb in 1998 in response to a test by India. The Pakistani scientist who built the bomb, Abdul Qadeer Khan, had access to sensitive technology in the Netherlands.

Khan admitted in 2004 that he ran a nuclear black-market, selling secrets to Iran, Libya and North Korea. Khan, who is considered a hero by many Pakistanis, later retracted his remarks and in 2009 was freed from house arrest.

The declassified documents were released after requests by the National Security Archive at George Washington University and the Woodrow Wilson Center for International Scholars.

William Burr, a scholar at the National Security Archive, said that a U.S. report from 1978 that could shed light on Khan's activities was missing and that he feared it had been destroyed.

The released documents said Pakistan wanted to maintain work on a reprocessing plant. France initially supported the project but backed out in 1978 due to fears that it would be used to produce weapons.

Then-Deputy Secretary of State Warren Christopher in a secret memo urged a "low profile" on France's decision, saying it would "severely embarrass" France's then-President Valery Giscard d'Estaing and impede future cooperation if it appeared he was responding to U.S. pressure.

Christopher also said he was urging the U.S. Congress to consider economic assistance and military sales to Pakistan, which was considered a U.S. ally in the Cold War when India tilted toward the Soviet Union.

Assistance to Pakistan can "perhaps relieve some of the tension and sense of isolation which give Pakistan greater incentive to move covertly in the nuclear field," wrote Christopher, who later served as secretary of state.

The United States eventually pursued a major assistance package for Pakistan as part of a partnership against the Soviets in Afghanistan. The United States later cut aid due to nuclear concerns - only to resume it again as it sought Pakistan's cooperation in Afghanistan following the Sept. 11, 2001, attacks.

President Barack Obama's administration recently suspended about one-third of its $2.7 billion annual defense aid to Pakistan to put pressure for more action against Islamic militants.

U.S. Navy Gets a New LCS Program Chief

The U.S. Navy's effort to develop and field the Littoral Combat Ship (LCS) got more focused after the July 11 establishment of a single program executive office that combined ship and mission module development efforts under a single leader. Rear Adm. James Murdoch, a previous director of the LCS ship development office, is the new PEO LCS, returning after about a year of working on fleet maintenance.

Despite the recent award of several construction contracts for both LCS variants, the program remains under occasional fire from congressional opponents, spurred by high costs, program decisions sometimes seen as hasty, reports of corrosion on Austal USA's USS Independence (LCS 2), and superstructure and weld cracks on Lockheed Martin's USS Freedom (LCS 1).

Murdoch addressed a number of issues during a July 20 interview at his Washington Navy Yard headquarters.

Q. WHAT'S YOUR ASSESSMENT OF THE LCS PROGRAM RIGHT NOW?

A. Overall, the program is pretty healthy. The shipbuilding side has reached a place where we're into the contracts we want; we're in serial production with a stable design. Mission packages, we're getting in to the test phase. The challenge now is to put it all together.

Establishing a single PEO gives an end-to-end responsibility for the warfare capability to one guy. We'll have one organization covering three big themes: getting the shipbuilding in a stable march down the learning curve; testing the mission packages with all their components and then into the ship; and introducing it into the fleet.

I recognize the concerns that recently surfaced, but frankly these are all part and parcel of the challenges in building ships, and complex ships at that. Where there are issues, we're going to assess, analyze and fix 'em.

Q. LCS 1 HAD TWO STRUCTURAL PROBLEMS: PERSISTENT CRACKING IN THE ALUMINUM SUPERSTRUCTURE AND A WELD SEAM BREACH. HAVE THOSE BEEN FIXED?

A. There was about a 6-inch crack in a weld. I'm certainly not happy with it, but this is pretty normal for a new warship design, to have some sorts of issues. My personal perspective is we probably had fewer problems with both of these ships than I might have expected, based on past Navy experience.

All ships work in a seaway. Navy ships go faster, generally speaking, so there's more potential for stress and strain.

When I was working this program earlier, I would see workers putting more scantlings, stiffeners, longitudinal frame members and so forth, into the structure. I would typically ask, "What are you guys doing?" Well, they said, "We were reviewing the design and decided that, based on structural models, we need to put a little more in here." I think actually the designs came out pretty well.

The hull crack in Freedom was in a chine area. I'm pretty confident from the summaries that this was a weld defect, didn't do it right. There are miles of linear welds on the ship and this is six inches. Once again, I'm not happy about that. We've looked at other places in the ship, haven't found any problems we need to go repair. And we've beefed the design a bit in that particular area, added some additional structure around that break point. I think the crack issue is understood; we've addressed it.

Superstructure cracking, frankly, is not uncommon, especially in ships that have aluminum superstructures. Aluminum is lighter by weight, it has the strength to hold the ship together and is more resistant to oxidation corrosion, and you don't have to paint it. But it has to be treated more carefully in terms of its fatigue life. We have the technology to get that right.

This is not something that keeps me awake at night. There are things you worry about in every job, but that's not one of them.

The corrosion that's recently resurfaced on LCS 2, we were looking for this. We've looked at it on both designs.

It's not a different mechanism of corrosion than what's taking place on [other Navy ships]. Where you have different materials used between the propellers in the water jets and the hull of the ship, you have to do a variety of things to prevent one of those metals corroding in sea water.

We made design decisions on both of these ships with regard to where to put zinc anodes, where are we going to employ impressed current cathodic protection systems. We thought we got the design pretty right, but in this and in other areas, we said, first one we built. So we're going to go in and look at them periodically.

In LCS 2, we found inside the water jet tunnels the paint surface had degraded, and we started having pitting corrosion which was obviously galvanic. So we'll put some additional aluminum plating around the water-jet tunnel area so I can continue operations until I can get her into dry dock, which was a planned evolution.

There is any number of risks, quite a few of which just didn't materialize. I had people telling me the water jet impellers would experience a lot of cavitation, degrade rapidly and not make it to the post-shakedown availability. We've gone in and inspected those, and they're behaving much more on the favorable side of the predicted model than the unfavorable side. So there are things in the design that went very well, better than expected.

I think we did a pretty fair job on this design, especially given the amount of time we took on it. We didn't get it exactly perfect, but it came out pretty well. And the areas we need to go fix are pretty fixable.

Q. COMPARED WITH LAST YEAR'S PUBLIC RELATIONS EFFORT TO SHOW OFF LCS 1, THERE HAS BEEN A DEARTH OF NEWS ABOUT THE INDEPENDENCE (LCS 2). IT'S OPERATING FROM MAYPORT, FLA., RATHER THAN THE MAIN FLEET BASE AT NORFOLK. IT HAS YET TO MAKE A SIGNIFICANT CRUISE. THERE IS ALMOST NO WORD OF ITS ACTIVITIES, FEW PHOTOS ARE RELEASED, AND AUSTAL USA, UNLIKE LOCKHEED MARTIN AND LCS 1, HAS BECOME VERY RELUCTANT TO TALK ABOUT THE SHIP. THE ONLY NEWS THAT'S OUT THERE IS ABOUT CORROSION PROBLEMS. IS LCS 2 BROKEN?

A. There's nothing wrong with LCS 2. Fair observations, I wouldn't dispute you. You could certainly draw the conclusion that you haven't heard about the ship, then, gosh, is there something wrong with it? That's why I'm here. I believe the fleet introduction of these ships is very important. When it comes to these ships, nobody cares like I care.

I guess I agree with you. LCS, in the press, has kind of gone sinker, and maybe we shouldn't have let that happen.

LCS 2 has been doing things. Vice Adm. Richard Hunt, commander of Naval Surface Forces, was on board last month. He watched them maneuver an unmanned vehicle around the mission bay, put it in the twin-boomed extensible crane, launch it from the ship. They operated it, drove it back into the recovery system, picked it up and brought it back aboard the ship. It was the first underway day he had in his new job, on the Independence. So why aren't we getting that message to you? I don't know.

Q. DO THE SHIPS' MISSION BAY HANDLING SYSTEMS WORK?

A. Not only have we launched and recovered and operated an unmanned surface vehicle, we've also recently launched and recovered the remote multimission vehicle. Handling is part of the main battery. I'm very pleased with where we are on both of these.

But we're building these ships at the affordable end of the spectrum here, so over time I expect the industry guys to get smart on these crane systems and provide me something they can procure affordably, that sailors can operate, that are reliable and maintainable.

I'm not looking for continual improvement in terms of being able to lift more weight. Both are pretty good. I'm always looking for something that makes the ship more affordable.

Q. ARE THERE ANY SIGNIFICANT RELIABILITY ISSUES WITH EITHER HANDLING SYSTEM?

A. Not to my knowledge. Both systems are solid designs. I'm pretty confident in the systems.

Q. WHEN CAN THE FLEET EXPECT AN OPERATIONALLY EFFECTIVE, DEPLOYABLE, NON-TEST LCS WITH A MISSION MODULE?

A. By the end of 2012, I would like to have that mine warfare mission package testing over and done with. I need that to wrap that up and the testers need to do all their reporting. The real question you're asking me is, when does LCS 1 go out on its first all-operational cycle of deployment? My suspicion is that would be more likely to occur sometime in 2013.

Thai Army Probes Series of Chopper Crashes

BANGKOK - Thailand's army has grounded a number of its helicopter fleet, a military official said July 25, after a string of deadly chopper crashes that some have blamed on angry jungle spirits.

On July 24, three troops were killed when a Bell 212 helicopter went down in Phetchaburi province, southwest of Bangkok - one of three helicopter crashes in the area in little over a week that have together claimed 17 lives.

The crashes had spooked the superstitious even before it emerged that the third chopper had carried the bodies of those killed in the second helicopter, which had in turn been sent to retrieve those who died in the first crash.

"It is a big loss," Maj. Gen. Pitaya Krajangwong, the Thai army aviation commander, told a press conference in the capital.

He said the first two crashes, involving a Huey and a Black Hawk helicopter respectively, seemed on initial investigation to be caused by bad weather, while in the third incident the Bell 212 appeared to have a tail rota fault.

"The other 20 Bell 212 choppers will not fly until they are well-checked.

Once it is found that there is nothing wrong, they can go back to missions," he said, adding that a formal 30-day investigation into the crashes would be held.

The Bell lost on July 24, which was travelling from Bangkok to a task force base in Phetchaburi, had a day earlier transported bodies from a Black Hawk helicopter crash on Tuesday, in which nine people were killed.

The victims were eight military personnel and a television cameraman.

The Black Hawk was found in dense forest just across the border in Myanmar on July 22, three days after it disappeared during a mission to recover the bodies of five soldiers killed in the Huey helicopter accident on July 16.

The strange sequence of events has sparked a range of theories among those living in jungle-heavy areas close to the crash sites, according to Thai media.

A number of military and civilians "believe bad omens are to blame" and have cited earlier predictions by a fortune teller, the English-language Bangkok Post reported July 25.

"The guardian spirits here are very fierce," said one villager quoted by the paper.

The Thai Rath newspaper said the Ministry of Natural Resources and Environment planned to hold a ceremony on July 25 to pay respect to spirits believed to be in the jungle.

Top army brass and politicians, including outgoing premier Abhisit Vejjajiva, attended a Buddhist ceremony for the victims of the Black Hawk crash in the western province of Kanchanburi on Monday.

Army chief Gen. Prayut Chan-O-Cha was initially due to travel to the service by helicopter but changed his plans and went by car, Pitaya said.

Mullen: 'Very Difficult' Time in U.S.-Pakistan Ties

WASHINGTON - The top U.S. military chief warned July 25 that U.S.-Pakistan military-to-military ties were at a "very difficult" crossroads, allowing that a path to progress on that front was not yet clear.

President Barack Obama's administration recently suspended about a third of its $2.7 billion annual defense aid to Pakistan in the wake of the raid that killed Osama bin Laden near the country's main military academy. But it assured Islamabad it is committed to a $7.5 billion civilian assistance package approved in 2009.

"We are in a very difficult time right now in our military-to-military relations," Joint Chiefs of Staff Chairman Adm. Mike Mullen told a press briefing billed as his last before retirement.

Despite the strain, Mullen said "I don't think that we are close to severing" those ties.

And the retiring admiral said he hoped the two nations would soon find a way to "recalibrate" those ties.

Still, Mullen acknowledged: "we need to work through the details of how this (recalibration) is going to happen."

Top U.S. officer Mullen has suggested that Pakistan's army or Inter-Services Intelligence agency likely killed journalist Saleem Shahzad, who had reported about militants infiltrating the military.

On a visit to Washington, Pakistan's former military ruler Pervez Musharraf staunchly defended the army and ISI. He denied any Pakistani support for bin Laden, who apparently moved to the garrison town of Abbottabad while Musharraf was in power.

U.S. officials have long questioned Pakistani intelligence's ties with extremists, including Afghanistan's al-Qaida-linked Haqqani network and the anti-Indian movement Lashkar-e-Taiba that allegedly plotted the grisly 2008 assault on Mumbai.

Adm. James Winnefeld, nominated to be the number two U.S. military officer, described Pakistan as a "very, very difficult partner."

"We don't always share the same worldview or the same opinions or the same national interest," Winnefeld told his Senate confirmation hearing last week.

Obama has nominated Gen. Martin Dempsey as chairman of the Joint Chiefs of Staff; Dempsey is due to succeed Mullen, who is retiring at his term's end Sept. 30.

Israel Nabs Boat Smuggling Weapons on Dead Sea

JERUSALEM - The Israeli military and police captured a boat on the Dead Sea which was trying to smuggle weapons from Jordan, and detained two Palestinians on board, officials said on July 25.

The Israeli military said the boat was smuggling weapons from Jordan and that 10 Kalashnikov assault rifles and 10 magazines were found on board the dinghy.

"This was effectively a smuggling attempt from Jordan to the (Palestinian) territories. They were stopped at dawn. There were 10 Kalashnikovs, and 10 full magazines in the boat," an Israeli military spokeswoman told AFP.

She said the men detained, who were being questioned by police, were Palestinians from the West Bank.

The Dead Sea is the lowest place in the world and it stretches some 43 miles along the border with Jordan, while its northern and western shores touch Israel and the West Bank.

Israeli police spokesman Micky Rosenfeld confirmed that the boat had come from Jordan.

"There is an ongoing police investigation involving a number of arms that were attempted to be smuggled from Jordan," he told AFP. "Two suspects have been arrested and are being questioned. The arrests were made this morning and a number of weapons were confiscated."

Israel's army radio said the vessel was a dinghy that had come from Jordan and was trying to traffic arms into the West Bank.

Very few vessels are able to sail on the inland lake. Due to the density of the water - the Dead Sea has a salt and mineral content which is seven times more concentrated than sea water - boats float very high and run a considerable risk of capsizing.

It was not the first time the army has stopped a boat containing weapons on the Dead Sea, although such attempts are rare.

In October 2006, Israeli troops thwarted an attempt to smuggle weapons and drugs from Jordan into Israel via the Dead Sea.

A military patrol spotted an inflatable craft approaching from Jordan and gave chase, arresting the two men on board - an Israeli Bedouin from Khirbet Khasif in the southern Negev desert, and a Palestinian resident of Jordan.

Months later, media reports said the navy had started looking into the possibility of organising regular patrols on the sea in an bid to prevent the infiltration of people and weapons from Jordan into the Palestinian territories.

Because of the high salinity of the water, tests were being conducted to examine what kind of patrol vessel could withstand erosion from the salt, they said.

In February 1998, the Israeli army has arrested a Palestinian man after discovering a large quantity of arms on the northern coast of the Dead Sea which had been brought in from Jordan in two motor boats.

3 U.S. Weapons Move Toward Frontlines

A lighter 60mm mortar is gun-up, new tank ammo is loaded but in a tactical pause, and the lightweight .50-caliber machine gun is clearing a considerable jam. Such is the status of three key weapon and munitions programs by the U.S. Army.

The service awarded ATK a $77 million, three-year contract to develop and qualify the M829E4 120mm Advanced Kinetic Energy tactical tank round, a 5th-generation munition meant to be much more lethal against faraway targets with advanced explosive reactive armor.

"This round provides added kill capability without added responsibility," said Craig Aakhus, ATK's engineering director for tank ammo.

But its greatest threat may not be on the battlefield. Congress in the 2011 National Defense Authorization Act ordered a cost-benefit analysis of future M1 Abrams munitions "to determine the proper investment to be made in tank munitions, including beyond-line-of-sight technology." The analysis will address predicted operational performance of each munition in close-, mid- and long-range uses, and beyond line of sight, and must include the Advanced Kinetic Energy round, as well as the Mid-Range Munition and Advanced Multipurpose Program.

The analysis was due by April 15, but the Army was allowed to push that back. Service officials did not respond when asked when the new report would be presented.

Jeff Janey, ATK's director for strategy and business development, was confident that the round's "leap ahead in capability" will more than cover its "incremental cost increase."

Since 1980, ATK has developed 10 of the 12 tank rounds and delivered more than 4 million tactical and training rounds to the Army, Marines and allied militaries.

ATK demonstrated in Phase I of testing that the Advanced Kinetic Energy round can meet all threshold requirements. Reliability will be put to the test over the next 31 months, with a critical design review coming about 20 months in. A low-rate initial production of 800 rounds will follow Phase II, with live-fire tests at Yuma Proving Ground, Ariz. If all goes according to plan, production of about 4,200 rounds will begin in the summer of 2014.

Still, the armor force of the future remains in a confusing quagmire. On one hand, there is much debate as to where - and in what quantity - tanks fit into future operations. Military and congressional leaders alike have increasingly pushed for an expeditionary Army centered on low-intensity, counterterrorism and counterinsurgency operations, with fewer heavy forces sitting in a peripheral stand-by.

The Combat Vehicle Portfolio review stands as the primary factor for finding the right force. The Army this summer asked Congress to divert $124.5 million slated for a materiel development decision for the Abrams tank until the review is completed, which is expected at any time.

The Army also looks to save money by shutting down tank production lines for the first time since 1941.

Chief of Staff Gen. Martin Dempsey, at a May 18 Senate subcommittee hearing on defense appropriations, said though shutting down the plant and losing that "expert force" has undeniable costs, budget considerations required it, particularly since the Abrams inventory "is among the most modern of any of our equipment," with an average age of just over two years old, and keeping the plant open with minimum production was not fiscally responsible.

The House Appropriations defense subcommittee didn't agree; it added $272 million to the Army's budget request and ordered the service to buy more tanks. In addition, 120 lawmakers in May signed a bipartisan letter arguing the Army would save more money keeping the production line open rather than closing it and paying the associated costs. It will cost General Dynamics $380 million to shut down the plant and mothball the equipment, and an additional $1.3 billion to restart production, said Mike Cannon, General Dynamics' senior vice president for ground combat systems.

At the proposed end of production in 2013, the Army's tank fleet will include 1,547 M1A2 System Enhance Package tanks, mostly fielded to active units, and 791 M1A1 tanks, all fielded to National Guard units.

The Army in July also asked for an extra $31 million for the Abrams Upgrade Program. The tanks are experiencing greater-than-expected washout rates in regard to gun tubes, engines, transmissions, final drives, high hard armor plates in the sponson area, ammunition doors and rails.

GUNS, MORTARS

Low-rate initial production of 800 XM806 lightweight .50-caliber machine guns started in February. A pierced primer during limited user testing halted progress, said Lt. Col. Thomas Ryan, product manager of crew-served weapons for Program Executive Office Soldier. Delivery, which was expected by 2014, is now delayed 17 months.

While no one likes a delay, finding this fault early in the process has allowed the Army to build a more reliable and durable weapon, Ryan said. The service dropped an additional $45 million on a re-engineered bolt, adjustments to the fixed head space and new tests. Officials have put 300,000 rounds downrange and the results have been strong.

The XM806 cuts the weight of the 128-pound M2 by half and reduces recoil by 60 percent. It also boasts an effective range of 2,000 meters, 170 better than the M2. The machine gun, which has a manual safety, allows for quick barrel changes that do not require adjustments for head space and timing.

Relief also is on the way for the A-gunner tapped to carry the tripod. The XM205 weighs 13 pounds less than the 44-pound M3 now being carried. The XM205 collapses to less than 50 percent of deployed height.

Trigger pullers aren't the only ones getting some relief. The 1st Special Forces Group in Fort Lewis, Wash., has become the first unit to receive the latest M224A1 60mm Lightweight Company Mortar System. The new mortar knocks 20 percent off its predecessor's 46-pound weight while maintaining its max range, which is better than two miles. This was made possible by cutting out a few components and using a nickel-based super alloy called Inconel to make cannon tubes. The material is lighter, more durable, and needs less maintenance, officials said.

The Army will replace all 1,550 of its 60mm mortars with this new system by 2014, officials said. Ë

Toxins Grounded F-22s: Sources

The U.S. Air Force's fleet of F-22 Raptor fighters has been grounded since May 3 due to toxins entering the cockpit via the aircraft's life support systems, sources with extensive F-22 experience said.

Service leaders grounded the stealthy twin-engine fighter after pilots suffered "hypoxialike symptoms" on 14 occasions. The incidents affected Raptor pilots at six of seven F-22 bases; the exception is Tyndall Air Force Base, Fla.

But despite an investigation that has spanned nearly three months, no one yet knows what toxin or combinations of toxins might have caused the incidents, nor is it clear exactly how the chemicals are entering the pilots' air supply, sources said.

Toxins found in pilots' blood include oil fumes, residue from burned polyalphaolefin (PAO) anti-freeze, and, in one case, propane. Carbon monoxide, which leaves the blood quickly, is also suspected.

"There is a lot of nasty stuff getting pumped into the pilots' bloodstream through what they're breathing from that OBOGS [On-Board Oxygen Generation System]. That's fact," one former F-22 pilot said. "How bad it is, what type it is, exactly how much of it, how long - all these things have not been answered."

The blood tests were performed after each of the 14 incidents in which pilots reported various cognitive dysfunctions and other symptoms of hypoxia. One couldn't remember how to change radio frequencies. Another scraped trees on his final approach to the runway - and later could not recall the incident.

"These guys are getting tested for toxins and they've [gotten] toxins out of their bloodstreams," the source said. "One of the guys was expelling propane."

This source, along with the others, requested anonymity for fear of retribution.

The line of inquiry may shed new light on the death of Capt. Jeff "Bong" Haney, a 525th Fighter Squadron pilot who was killed when his F-22 crashed last November near Anchorage. Sources said that in Haney's last few radio calls before his jet disappeared, he sounded drunk, a classic sign of hypoxia. Haney was known as a prodigiously skilled aviator who was in line to attend the elite Air Force Weapons School.

Air Force officials have said they have not yet completed the investigation into the crash.

Asked for comment about the possibility that F-22 pilots had been exposed to carbon monoxide, an Air Force spokesman, Maj. Chad Steffey said, "The safety of our aircrews is paramount, and the Air Force continues to carefully study all factors of F-22 flight safety."

Asked about other toxins, Steffey referred questions to the Air Force Safety Center at Kirtland AFB, N.M., where officials did not repond by press time.

Officials with Lockheed Martin, which builds the aircraft, said they are cooperating with the investigation but cannot comment further.

Carbon Monoxide?

Beside the various toxins found in the pilots' blood, carbon monoxide is another potential cause of the hypoxia incidents.

The gas, one of many generated as exhaust by the plane's jet engines, might be getting into the cockpit, sources said.

Part of the problem, at least for pilots flying from Joint Base Elmendorf-Richardson, Alaska, where many of the known incidents have occurred, may be the startup procedures used in winter, one source said.

Because of the harsh climate, pilots often start their jet engines inside a hangar before taking off. That could allow exhaust gases to be trapped in the building, sucked back into the engines, and ingested into the bleed air intakes that are located within the engines' compressor sections that supply the OBOGS, sources said. The layout, sources added, is standard for modern jet aircraft.

But another source said that many of the hypoxia incidents have occurred well into flights or even during a day's second mission, long after the plane has left the Elmendorf hangar.

The U.S. Navy had problems with the OBOGS on its F/A-18 Hornet, which sucked carbon monoxide into its oxygen system during carrier operations. Between 2002 and 2009, Hornet aviators suffered 64 reported episodes of hypoxia, including two that killed the pilots, according to the July-August 2010 issue of "Approach," a Navy Safety Center publication.

The Navy modified the planes' OBOGS, has had no recent similar incidents and is not currently investigating the systems, Naval Air Systems Command officials said.

USAF Expands Investigation

In January, a safety investigation board led by Maj. Gen. Steven Hoog began looking into the the OBOGS on the F-16, F-15E and F-35 fighters; the A-10 attack jet and the T-6 trainer, according to May statements by officials with the service's Air Combat Command, which oversees combat aircraft.

In May, Air Force Secretary Michael Donley had ordered the service's Scientific Advisory Board to conduct a "quick-look study, gather and evaluate information, and recommend any needed corrective actions on aircraft using on-board oxygen generation systems," according to a July 21 statement by service officials.

The release indicated that the service is now looking at more types of aircraft: the B-1 and B-2 bombers and the CV-22 tilt-rotor and "other aircraft as appropriate."

According to the release, the investigation is conducting a "series of carefully controlled in-flight tests, the team will examine the subsystems identified in reported incidents. These include the pressurization system, mask and cockpit oxygen levels."

The release said the Scientific Advisory Board investigation followed the grounding of the F-22 fleet, but did not say whether it superseded, replaced or is merely accompanying the Hoog investigation.

One source said that F-22 test pilots at Edwards AFB, Calif., last week started flying sorties as the investigate OBOGS concerns as part of the Air Force safety investigation.

Air Force officials have confirmed only that some test pilots at the base are flying their jets under a special waiver granted to them to test an unrelated software upgrade.

However, the operational fleet remains grounded, with pilots and ground crews practicing in simulators as much as they can. But that is not a real solution because the pilots won't be able to maintain currency, one former F-22 pilot said.

"After 210 days, they've got to start retraining everybody," he said.

It would take weeks for the instructor pilots at Tyndall to re-qualify themselves and then start to train others, the former pilot said. Pilots with lapped currencies would be re-qualifying each other.

It would take four to six weeks afterward to re-qualify the operational squadrons. Service officials confirmed that 12 Raptors are stranded at Hill AFB, Utah, but declined to identify their squadron. The jets came to the desert base for a Combat Hammer exercise in which pilots and ground crews practice loading and releasing live air-to-ground weapons. Service officials said the jets are from the 1st Fighter Wing at Langley AFB, Va.

Meanwhile, Lockheed can't deliver new Raptors to the Air Force because the company and the Pentagon's Defense Contract Management Agency are unable to fly required test sorties needed to certify the jets meet specifications. Four aircraft have technically been delivered to the service but can't fly to their new home at Langley AFB.

At least two additional aircraft have been completed but remain at the factory undelivered.