SMITHFIELD, N.C. - The airplanes of Aero Contractors Ltd. take off from Johnston County Airport here, then disappear over the scrub pines and fields of tobacco and sweet potatoes. Nothing about the sleepy Southern setting hints of foreign intrigue. Nothing gives away the fact that Aero's pilots are the discreet bus drivers of the battle against terrorism, routinely sent on secret missions to Baghdad, Cairo, Tashkent and Kabul.

When the Central Intelligence Agency wants to grab a suspected member of Al Qaeda overseas and deliver him to interrogators in another country, an Aero Contractors plane often does the job. If agency experts need to fly overseas in a hurry after the capture of a prized prisoner, a plane will depart Johnston County and stop at Dulles Airport outside Washington to pick up the C.I.A. team on the way.

Aero Contractors' planes dropped C.I.A. paramilitary officers into Afghanistan in 2001; carried an American team to Karachi, Pakistan, right after the United States Consulate there was bombed in 2002; and flew from Libya to Guantánamo Bay, Cuba, the day before an American-held prisoner said he was questioned by Libyan intelligence agents last year, according to flight data and other records.

While posing as a private charter outfit - "aircraft rental with pilot" is the listing in Dun and Bradstreet - Aero Contractors is in fact a major domestic hub of the Central Intelligence Agency's secret air service. The company was founded in 1979 by a legendary C.I.A. officer and chief pilot for Air America, the agency's Vietnam-era air company, and it appears to be controlled by the agency, according to former employees.

Behind a surprisingly thin cover of rural hideaways, front companies and shell corporations that share officers who appear to exist only on paper, the C.I.A. has rapidly expanded its air operations since 2001 as it has pursued and questioned terrorism suspects around the world.

An analysis of thousands of flight records, aircraft registrations and corporate documents, as well as interviews with former C.I.A. officers and pilots, show that the agency owns at least 26 planes, 10 of them purchased since 2001. The agency has concealed its ownership behind a web of seven shell corporations that appear to have no employees and no function apart from owning the aircraft.

The planes, regularly supplemented by private charters, are operated by real companies controlled by or tied to the agency, including Aero Contractors and two Florida companies, Pegasus Technologies and Tepper Aviation.

The civilian planes can go places American military craft would not be welcome. They sometimes allow the agency to circumvent reporting requirements most countries impose on flights operated by other governments. But the cover can fail, as when two Austrian fighter jets were scrambled on Jan. 21, 2003, to intercept a C.I.A. Hercules transport plane, equipped with military communications, on its way from Germany to Azerbaijan.

"When the C.I.A. is given a task, it's usually because national policy makers don't want 'U.S. government' written all over it," said Jim Glerum, a retired C.I.A. officer who spent 18 years with the agency's Air America but says he has no knowledge of current operations. "If you're flying an executive jet into somewhere where there are plenty of executive jets, you can look like any other company."

Some of the C.I.A. planes have been used for carrying out renditions, the legal term for the agency's practice of seizing terrorism suspects in one foreign country and delivering them to be detained in another, including countries that routinely engage in torture. The resulting controversy has breached the secrecy of the agency's flights in the last two years, as plane-spotting hobbyists, activists and journalists in a dozen countries have tracked the mysterious planes' movements.

Inquiries From Abroad

The authorities in Italy and Sweden have opened investigations into the C.I.A.'s alleged role in the seizure of suspects in those countries who were then flown to Egypt for interrogation. According to Dr. Georg Nolte, a law professor at the University of Munich, under international law, nations are obligated to investigate any substantiated human rights violations committed on their territory or using their airspace.

Dr. Nolte examined the case of Khaled el-Masri, a German citizen who American officials have confirmed was pulled from a bus on the Serbia-Macedonia border on Dec. 31, 2003, and held for three weeks. Then he was drugged and beaten, by his account, before being flown to Afghanistan.

The episode illustrates the circumstantial nature of the evidence on C.I.A. flights, which often coincide with the arrest and transporting of Al Qaeda suspects. No public record states how Mr. Masri was taken to Afghanistan. But flight data shows a Boeing Business Jet operated by Aero Contractors and owned by Premier Executive Transport Services, one of the C.I.A.-linked shell companies, flew from Skopje, Macedonia, to Baghdad and on to Kabul on Jan. 24, 2004, the day after Mr. Masri's passport was marked with a Macedonian exit stamp.

Mr. Masri was later released by order of Condoleezza Rice, the national security adviser at the time, after his arrest was shown to be a case of mistaken identity.

A C.I.A. spokeswoman declined to comment for this article. Representatives of Aero Contractors, Tepper Aviation and Pegasus Technologies, which operate the agency planes, said they could not discuss their clients' identities. "We've been doing business with the government for a long time, and one of the reasons is, we don't talk about it," said Robert W. Blowers, Aero's assistant manager.

A Varied Fleet

But records filed with the Federal Aviation Administration provide a detailed, if incomplete, portrait of the agency's aviation wing.

The fleet includes a World War II-era DC-3 and a sleek Gulfstream V executive jet, as well as workhorse Hercules transport planes and Spanish-built aircraft that can drop into tight airstrips. The flagship is the Boeing Business Jet, based on the 737 model, which Aero flies from Kinston, N.C., because the runway at Johnston County is too short for it.

Most of the shell companies that are the planes' nominal owners hold permits to land at American military bases worldwide, a clue to their global mission. Flight records show that at least 11 of the aircraft have landed at Camp Peary, the Virginia base where the C.I.A. operates its training facility, known as "the Farm." Several planes have also made regular trips to Guantánamo.

But the facility that turns up most often in records of the 26 planes is little Johnston County Airport, which mainly serves private pilots and a few local corporations. At one end of the 5,500-foot runway are the modest airport offices, a flight school and fuel tanks. At the other end are the hangars and offices of Aero Contractors, down a tree-lined driveway named for Charlie Day, an airplane mechanic who earned a reputation as an engine magician working on secret operations in Laos during the Vietnam War.

"To tell you the truth, I don't know what they do," said Ray Blackmon, the airport manager, noting that Aero has its own mechanics and fuel tanks, keeping nosey outsiders away. But he called the Aero workers "good neighbors," always ready to lend a tool.

Son of Air America

Aero appears to be the direct descendant of Air America, a C.I.A.-operated air "proprietary," as agency-controlled companies are called.

Just three years after the big Asian air company was closed in 1976, one of its chief pilots, Jim Rhyne, was asked to open a new air company, according to a former Aero Contractors employee whose account is supported by corporate records.

"Jim is one of the great untold stories of heroic work for the U.S. government," said Bill Leary, a professor emeritus of history at the University of Georgia who has written about the C.I.A.'s air operations. Mr. Rhyne had a prosthetic leg - he had lost one leg to enemy antiaircraft fire in Laos - that was blamed for his death in a 2001 crash while testing a friend's new plane at Johnston County Airport.

Mr. Rhyne had chosen the rural airfield in part because it was handy to Fort Bragg and many Special Forces veterans, and in part because it had no tower from which Aero's operations could be spied on, a former pilot said.

"Sometimes a plane would go in the hangar with one tail number and come out in the middle of the night with another," said the former pilot. He asked not to be identified because when he was hired, after responding to a newspaper advertisement seeking pilots for the C.I.A., he signed a secrecy agreement.

While flying for Aero in the 1980's and 1990's, the pilot said, he ferried King Hussein, Jordan's late ruler, around the United States; kept American-backed rebels like Jonas Savimbi of Angola supplied with guns and food; hopped across the jungles of Colombia to fight the drug trade; and retrieved shoulder-fired Stinger missiles and other weapons from former Soviet republics in Central Asia.

Ferrying Terrorism Suspects

Aero's planes were sent to Fort Bragg to pick up Special Forces operatives for practice runs in the Uwharrie National Forest in North Carolina, dropping supplies or attempting emergency "exfiltrations" of agents, often at night, the former pilot said. He described flying with $50,000 in cash strapped to his legs to buy fuel and working under pseudonyms that changed from job to job.

He does not recall anyone using the word "rendition." "We used to call them 'snatches,' " he said, recalling half a dozen cases. Sometimes the goal was to take a suspect from one country to another. At other times, the C.I.A. team rescued allies, including five men believed to have been marked by Muammar el-Qaddafi, the Libyan leader, for assassination.

Since 2001, the battle against terrorism has refocused and expanded the C.I.A.'s air operations. Aero's staff grew to 79 from 48 from 2001 to 2004, according to Dun and Bradstreet.

Despite the difficulty of determining the purpose of any single flight or who was aboard, the pattern of flights that coincide with known events is striking.

When Saddam Hussein was captured in Iraq the evening of Dec. 13, 2003, a Gulfstream V executive jet was already en route from Dulles Airport in Washington. It was joined in Baghdad the next day by the Boeing Business Jet, also flying from Washington.

Flights on this route were highly unusual, aviation records show. These were the first C.I.A. planes to file flight plans from Washington to Baghdad since the beginning of the war.

Flight logs show a C.I.A. plane left Dulles within 48 hours of the capture of several Al Qaeda leaders, flying to airports near the place of arrest. They included Abu Zubaida, a close aide to Osama bin Laden, captured on March 28, 2002; Ramzi bin al-Shibh, who helped plan 9/11 from Hamburg, Germany, on Sept. 10, 2002; Abd al-Rahim al-Nashri, the Qaeda operational chief in the Persian Gulf region, on Nov. 8, 2002; and Khalid Shaikh Mohammed, the architect of 9/11, on March 1, 2003.

A jet also arrived in Riyadh, Saudi Arabia, from Dulles on May 31, 2003, after the killing in Saudi Arabia of Yusuf Bin-Salih al-Ayiri, a propagandist and former close associate of Mr. bin Laden, and the capture of Mr. Ayiri's deputy, Abdullah al-Shabrani.

Flight records sometimes lend support to otherwise unsubstantiated reports. Omar Deghayes, a Libyan-born prisoner in the American detention center at Guantánamo Bay, Cuba, has said through his lawyer that four Libyan intelligence service officers appeared in September in an interrogation cell.

Aviation records cannot corroborate his claim that the men questioned him and threatened his life. But they do show that a Gulfstream V registered to one of the C.I.A. shell companies flew from Tripoli, Libya, to Guantánamo on Sept. 8, the day before Mr. Deghayes reported first meeting the Libyan agents. The plane stopped in Jamaica and at Dulles before returning to the Johnston County Airport, flight records show.

The same Gulfstream has been linked - through witness accounts, government inquiries and news reports - to prisoner renditions from Sweden, Pakistan, Indonesia and Gambia.

Most recently, flight records show the Boeing Business Jet traveling from Sudan to Baltimore-Washington International Airport on April 17, and returning to Sudan on April 22. The trip coincides with a visit of the Sudanese intelligence chief to Washington that was reported April 30 by The Los Angeles Times.

Mysterious Companies

As the C.I.A. tries to veil such air operations, aviation regulations pose a major obstacle. Planes must have visible tail numbers, and their ownership can be easily checked by entering the number into the Federal Aviation Administration's online registry.

So, rather than purchase aircraft outright, the C.I.A. uses shell companies whose names appear unremarkable in casual checks of F.A.A. registrations.

On closer examination, however, it becomes clear that those companies appear to have no premises, only post office boxes or addresses in care of lawyers' offices. Their officers and directors, listed in state corporate databases, seem to have been invented. A search of public records for ordinary identifying information about the officers - addresses, phone numbers, house purchases, and so on - comes up with only post office boxes in Virginia, Maryland and Washington, D.C.

But whoever created the companies used some of the same post office box addresses and the same apparently fictitious officers for two or more of the companies. One of those seeming ghost executives, Philip P. Quincannon, for instance, is listed as an officer of Premier Executive Transport Services and Crowell Aviation Technologies, both listed to the same Massachusetts address, as well as Stevens Express Leasing in Tennessee.

No one by that name can be found in any public record other than post office boxes in Washington and Dunn Loring, Va. Those listings for Mr. Quincannon, in commercial databases, include an anomaly: His Social Security number was issued in Washington between 1993 and 1995, but his birth year is listed as 1949.

Mr. Glerum, the C.I.A. and Air America veteran, said the use of one such name on more than one company was "bad tradecraft: you shouldn't allow an element of one entity to lead to others."

He said one method used in setting up past C.I.A. proprietaries was to ask real people to volunteer to serve as officers or directors. "It was very, very easy to find patriotic Americans who were willing to help," he said.

Such an approach may have been used with Aero Contractors. William J. Rogers, 84, of Maine, said he was asked to serve on the Aero board in the 1980's because he was a former Navy pilot and past national commander of the American Legion. He knew the company did government work, but not much more, he said. "We used to meet once or twice a year," he said.

Aero's president, according to corporate records, is Norman Richardson, a North Carolina businessman who once ran a truck stop restaurant called Stormin' Norman's. Asked about his role with Aero, Mr. Richardson said only: "Most of the work we do is for the government. It's on the basis that we can't say anything about it."

Secrecy Is Difficult

Aero's much-larger ancestor, Air America, was closed down in 1976 just as the United States Senate's Church Committee issued a mixed report on the value of the C.I.A.'s use of proprietary companies. The committee questioned whether the nation would ever again be involved in covert wars. One comment appears prescient.

When one C.I.A. official told the committee that a new air proprietary should be created only if "we have a chance at keeping it secret that it is C.I.A.," Lawrence R. Houston, then agency's general counsel, objected.

In the aviation industry, said Mr. Houston, who died in 1995, "everybody knows what everybody is doing, and something new coming along is immediately the focus of a thousand eyes and prying questions."

He concluded: "I don't think you can do a real cover operation."

Ford Fessenden contributed reporting for this article.