On Dec. 4, 2001, five members of a Las Vegas-based charter crew were detained by Russian authorities after they landed without visas in Petropavlovsk. The remote Russian city, located on the Kamchatka peninsula and surrounded by active volcanoes, is nine time zones east of Moscow and cannot be reached by road.

Three days earlier, the privately owned Boeing 737 had left Biggs Army Airfield in Texas, carrying the crew and 16 Americans traveling on tourist visas. The plane, a luxury aircraft outfitted with wood paneling and a three-hole putting green, had been chartered by a small company from Enterprise, Alabama, called Maverick Aviation.

What the plane and its passengers were really doing in Russia in the middle of winter is only hinted at in an appeal filed by two federal prisoners this year. But interviews with those involved in the case reveal a secretive, and sometimes comical, mission to strike back at the Taliban after 9/11 — a rare glimpse into the CIA’s efforts in Afghanistan.

According to unclassified court documents, the group was traveling to a helicopter plant in Siberia, where Maverick Aviation, which was experienced in acquiring Russian aircraft for the US military, was planning to buy two helicopters for a “customer.”

Not mentioned: That “customer” was the Central Intelligence Agency.

The CIA needed Russian helicopters because of its clandestine operations in Afghanistan. On Sept. 24, 2001, a Russian-made helicopter loaded with $10 million in cash carried a small CIA team into Afghanistan’s Panjshir Valley. Code-named “Jawbreaker,” the mission was to cement support among tribal leaders and pave the way for US military operations. It was the first entry of Americans into Afghanistan after the terrorist attacks of Sept. 11.

The aging helicopter, an Mi-17, was the team’s only way of getting in or out of the country. Though hardly state-of-the-art, the Russian helicopter had a distinct advantage for the CIA: it allowed the agency to operate relatively unnoticed in an area where Russian equipment left over from the Soviet occupation was commonplace.

There was only one problem: The CIA owned only one Russian helicopter. It needed more, but a clandestine American agency couldn’t exactly pick up the phone and call a Russian factory. So it turned to Jeffrey Stayton, then the chief of the Aviation Division at the US Army Test and Evaluation Command and an expert in Russian copters.

Stayton’s plan was to find a private American company to buy the helicopters, send a team of people over to pick them up from a plant in Siberia, modify them to CIA standards, and then get them to Uzbekistan, a staging ground for CIA operations into Afghanistan. And they would do it all within a matter of weeks.

Eventually, the team included William “Curt” Childree, whose company, Maverick Aviation, won the contract to buy the helicopters and organize logistics; Army personnel and contractors from El Paso with experience modifying Russian aircraft for use by the US military; and then “six guys from the customer’s office,” as Stayton put it (a CIA team that included special operations personnel).

That’s when things started to get complicated.

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In an interview, the pilot, Fred Sorenson, said he thought visas they had ordered would arrive by FedEx by the time the plane landed. When he found out over satellite phone that the papers hadn’t arrived, the plane was already descending, so he hid the fact from the crew for fear of a cockpit argument. The team was detained on arrival.

In the end, the visas came, and the crew was released the next day. But when the plane finally made it to Ulan Ude, in Siberia, the crew and passengers faced more challenges. To say merely that it was cold does not capture the Siberian winter, where temperatures that month approached 30 degrees below zero. Even worse, the team was in a Russian hotel with spotty electricity and limited heat.

The charter crew was shocked at the conditions (Siberia, after all, was off the beaten track of their typical VIP clients), but the Army personnel from El Paso also seemed woefully unprepared. None of them had ever been to Russia before — some had never left Texas — and the rough conditions shocked them. “I had the sense that I might end up in a Russian jail,” Kimberly Boone, a Russian translator for the Army, later recounted in court testimony.

Several members of the team grew sick with flu-like symptoms. There was also a major hitch with the helicopters. According to the factory, there was the equivalent of a mechanic’s lien on the helicopters, and they couldn’t be released. While Stayton and Childree attempted to negotiate the release from the factory, the Army personnel were told to act like tourists on a winter getaway to Siberia: They visited a Buddhist monastery and shopped for fur coats.

Childree, by then suffering from pneumonia, flew to Moscow to meet with the broker, where he found that a competitor (no one knows for sure who) had apparently offered $30,000 to kill the deal.

After some heated discussions, the helicopters, which cost about $1.6 million each, were released.

Back in Siberia, meanwhile, Stayton was having problems with Brian Patterson, the Army warrant officer in charge of the El Paso team, who, according to multiple people on the trip, was drinking heavily.

Lisa Teuton, a flight attendant for the charter company, recalled several members of the El Paso team drinking and bragging about their work for the CIA. “It just blew me away,” said Teuton. “I thought they would have been more professional and more secretive.”

The charter crew, fed up with the delays and the conditions, threatened to leave, but the El Paso team was having none of it. According to Sorenson, chief warrant officer Patterson poked him in the shoulder and said: ‘If you leave, we’ll shoot you down.’ “

Patterson laughed when asked about the incident. “I would like to know how I could accomplish that,” he said.

That night, while the others were settled in their rooms, the crew surreptitiously checked out of the hotel. They used some of their remaining cash and alcohol to bribe airport personnel not to notify the Army of their departure. With no cash left for additional fuel, and no clearance to fly over China, the aircraft headed toward Japan, as the flight attendants kept watch out the windows to see if they really would be shot down.

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The real question was: Did anyone not know it was a CIA trip? The CIA team had traveled under the amusingly obvious cover name of Donovan Aerial Surveys (William “Wild Bill” Donovan is regarded as the father of the CIA). The Russians in Ulan Ude were wondering what a group of private Americans were doing in Siberia in the middle of winter buying helicopters.

“They were very curious the whole time [about] why we were there; they would ask questions: ‘What are you doing?’ ” Joe Perry, a master sergeant on the mission, recalled. “Our rooms were bugged . . . It was just unreal some of the things they were doing.”

Relations with the Army team had been bad from the start. Stayton was unhappy with many of them, and the CIA considered them a nuisance. After one final argument, Stayton informed the Army’s Patterson that his team was going home immediately on commercial flights. The CIA team would finish the work on the helicopters.

Less than a week later, the two helicopters were packed in an Antonov cargo plane. When Stayton and the CIA personnel left Russia on the evening of Dec. 31, 2001, they had just 30 minutes left on their visas.

From the perspective of the CIA, the mission to Siberia, whatever its quirks, was a success. But the contract, which was administered by Army officials in New Mexico unaware of CIA involvement, quickly attracted scrutiny from the Army Criminal Investigative Division.

Agents found some unusual things. For instance, Army officials paid the most of the $5 million contract in a credit card transaction in an El Paso bar called the “Cockpit Lounge.” More troubling, the file was missing signatures; included few of the required supporting documents; and no invoices. When asked by investigators to explain why he allowed so many irregularities to go unnoticed, Edwin Guthrie, the contracting officer, responded: “Sleep apnea.”

There were other strange aspects, all related to the CIA’s secret involvement. Money allotted to pay expenses associated with mystery “subcontractors” (CIA personnel traveling under fictitious names); helicopters bought by the military being given civilian registration numbers (another quirk of CIA aircraft); and large cash transactions (typical of Russia). “They, the government, really leaned on me,” said Childree, noting that provisions, such as support for the CIA personnel, were added on to the contract at the last minute.

Investigators also focused on all the problems that took place on the trip, which the El Paso team blamed on Maverick Aviation and Stayton. “It was a nightmare,” recounted Boone, the Russian translator (it was Boone’s first trip to Russia).

But John Wilson, whose company also competed for the helicopter contract and was interviewed by law enforcement officials, was surprised that anyone thought the problems were a big deal. Buying helicopters in Russia isn’t easy. “I sat there going: Is that all?” he said. “That’s a good trip; I mean, really, honestly and truthfully, that was a pretty good trip as far as normal stuff goes.”

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In December 2007, six years after the mission to Siberia, Army official Stayton and private contractor Childree went to trial in the Middle District of Alabama on charges of defrauding the government.

A five-year investigation into the mission that spanned from Ulan Ude to Enterprise revealed that just days after returning from the mission to Russia, Childree wired money from his bank account to pay off Stayton’s second mortgage — about $61,000.

Both Stayton and Childree maintain the payment was a loan between two friends of 30 years, and had nothing do with the contract. But Stayton never listed the financial relationship on a government disclosure form, and other than a thank-you note to Childree, the two men never memorialized the loan in any paperwork. Government prosecutors argued the problems on the mission were the result of Maverick Aviation’s lack of planning. The payment was not a loan, they said, but a payoff made so that Stayton would steer the contract to Childree’s company (although Maverick had the lowest price of three bidders) and to cover up his poor performance.

Complicating matters, the judge ruled that no classified information could be used at trial: no mention of the CIA, Afghanistan, or even “9/11.”

While acquitted of bribery, both men were convicted of fraud, and Stayton was found guilty of the additional charge of obstruction of justice. Both Childree and Stayton, who are appealing their conviction, believe that if the jury had known the real purpose of the helicopters, they would have understood the seemingly strange parts of the mission were not a cover up.

Childree, now 70, is scheduled to be released from prison next year; Stayton, 59, won’t be released until 2012. Both have been diagnosed with cancer and are receiving treatment in prison medical facilities.

Secrecy still has a weird effect on the case: Stayton, in interviews, won’t use the name “CIA” when referring to the mission, even though the agency, for its part, treats its “secret” Mi-17s as an inside joke. The first Russian helicopter in Afghanistan was painted with the fictitious tail number 91101 — a reference to the 9/11 attacks.

What never came out at trial was the crucial role the Mi-17s played in the early months of military operations, when they were used to transport and resupply CIA paramilitary teams in Afghanistan. One picture taken during Operation Anaconda in March 2002 shows one of the CIA aircraft bought by Maverick being used by special operations personnel to transport a wounded Northern Alliance member. Though widely available, the picture was classified by the government at trial.

In response to questions about the CIA’s involvement in the mission to Siberia and its procurement of Mi-17 helicopters, George Little, a CIA spokesman, replied: “The CIA does not, as a rule, comment one way or the other on allegations regarding the agency’s contractual relationships.”

Sharon Weinberger is the author of “A Nuclear Family Vacation” (Bloomsbury).