WASHINGTON, D.C. -- FBI officials promptly told the Federal Aviation Administration last August of the arrest of Zacarias Moussaoui, who raised suspicions at a Minnesota flight school, but FAA security officials took no action.

They saw no reason to check scores of other flight schools for Middle Eastern men seeking flight training, said a senior FAA official, speaking for the agency.

Courtroom drawing of Moussaoui Photo: William Hennessey Jr. AP

Rather, the FAA's decision may be remembered as one in a series of pre-Sept. 11 instances in which federal authorities did not fully recognize and respond to faint warning signals that a terrorist network was at work. FBI officials maintain that based on what was known at the time, the bureau did well to nab Moussaoui, who faces conspiracy charges and is suspected of being the 20th hijacker.

Besides being informed by the FBI, FAA personnel also learned about Moussaoui from another channel. A program manager at the Eagan flight school who first phoned the FBI about the young Frenchman of Moroccan descent also informally shared his concerns with as many as four FAA inspectors, according to several people familiar with the matter. But there is no indication that any of them relayed the information to FAA security officials.

FBI officials also made fateful decisions. After Moussaoui's arrest, bureau lawyers in Washington repeatedly declined requests from Minneapolis agents to seek a special warrant under the Foreign Intelligence Surveillance Act (FISA) authorizing a search of Moussaoui's laptop computer. That decision is being questioned by some FISA experts, who say it's possible a warrant would have been granted.

The special court that reviews FISA requests -- a federal panel that since 1999 has included U.S. District Judge Michael Davis of Minnesota -- has approved more than 12,000 Justice Department applications for covert search warrants and wiretaps and rejected only one since the act was passed in 1978, according to government reports.

Mary Schiavo, a former Transportation Department inspector general who handled FISA cases as a Justice Department attorney in the 1980s, said FBI officials in Washington may have had a regional bias in the Moussaoui case: "They probably assumed there's nothing going on in Minnesota."

After the Sept. 11 attacks, when authorities did search Moussaoui's computer, they found evidence that would have heightened suspicions that he was a terrorist.

Tips to FBI

The FBI was alerted to Moussaoui on Aug. 15 by two program managers at the Pan Am International Flight Academy in Eagan, who called the bureau's Minneapolis office and spoke to Special Agent Dave Rapp. They were concerned about Moussaoui's odd behavior -- he lacked a pilot's license, and they said he paid nearly $10,000 for a few lessons in a Boeing 747 flight simulator as an "ego thing."

FBI officials shared with other law enforcement agencies in a Twin Cities counter-terrorism task force what they knew about Moussaoui, a law enforcement official said. They debated whether to arrest him or to try to watch his movements. Given the scarce law enforcement resources and the easy paths out of the country, it was decided to detain him for overstaying his permitted 90-day visit. Agents of the Immigration and Naturalization Service arrested Moussaoui at his suburban motel on the eve of his first scheduled session in a 747 flight simulator.

Last month Moussaoui was indicted on six counts of conspiracy related to the Sept. 11 attacks. His trial is scheduled to begin Oct. 14.

But in mid-August, 3 1/2 weeks before 19 hijackers commandeered and crashed four passenger jets, FAA security officials showed only mild interest in the uncooperative foreigner sitting in a Sherburne County jail cell.

FBI officials had "multiple consultations" with the FAA about Moussaoui between his Aug. 16 arrest and Sept. 11, a senior law enforcement official said. But the FBI had received no leads suggesting that terrorists had recently received training at U.S. flight schools, the official said.

"The FBI did notify us about this," said the senior FAA official, who spoke on the condition that his name not be used. "But it was a notification which said, 'Here's what this guy did,' not that he was a terrorist.

"So here we have a guy acting strange who's in custody. As a result of that, we did not notify other flight schools. ... If this guy was a threat, taken to the most extreme, he was in custody, so it was not a worry."

Before Sept. 11, FBI tidbits on possible terrorism threats "couldn't always fit into a puzzle," the FAA official said. So word of the arrest of a flight student for suspicious behavior, while unusual, did not seem of extraordinary consequence.

At Pan Am, the program manager who first alerted the FBI to Moussaoui also shared his concerns in late August with the FAA's on-site inspector and three commercial airline inspectors taking a refresher course at the school, according to people familiar with his account.

Jan Orr Pelletti, the FAA on-site inspector at the time, declined to comment.

But one of the three inspectors, who spoke on condition of anonymity, said he remembered the program manager telling him and his colleagues of his concerns about Moussaoui. He said he and his colleagues agreed that alerting the FBI was "the right thing to do."

While the Pan Am manager didn't explicitly say so, the inspector said, the "logical extension" of his comments was that "this guy might be a terrorist" seeking to hijack or blow up a plane.

The inspector said he chose not to phone the FAA's security office because "security just ignores" flight standards inspectors.

Rep. Jim Oberstar, D-Minn., who watches over the aviation industry as the senior Democrat on the House Transportation and Infrastructure Committee, said past events have underscored the importance "of sharing information on credible terrorist threats."

The inspectors' reactions to learning about Moussaoui, he said, suggest that agency personnel "were not on a high state of alert."

Since the bombing of Pan Am Flight 103 over Scotland in 1988 and amid rising threats from Osama bin Laden's global Al-Qaida terrorist network, the FAA and FBI have improved communication in recent years. That includes posting an FAA liaison at FBI headquarters.

But Schiavo, the outspoken former Transportation Department inspector general, said that FAA officials had refused to believe that the United States faced a threat of domestic terrorism. She said that flight schools "fairly well salivated at the thought of getting lots of foreign students, and the FAA encouraged it."

"People didn't want to do anything to turn off the pipeline of foreign cash," she said.

"So the mere fact that the [Pan Am] flight school itself raised a red flag, which was totally against its own interests, should have been taken very, very seriously," said Schiavo, now an aviation disaster attorney.

Soon after Sept. 11, authorities would learn that Mohamed Atta and Marwan Al-Shehhi, the two men who who allegedly flew planes into the World Trade Center, and Ziad Jarrah, believed to be at the controls of the jet that crashed in Pennsylvania, all enrolled in Florida flight schools over the last two years. Hani Hanjour, believed to have guided the plane that hit the Pentagon, attended several flight schools in Arizona and California.

As part of aviation security legislation adopted after the attacks, flight schools now are required to clear any foreigner seeking admission with the Justice Department.

The FAA also issued an advisory urging flight schools to watch for unusual behavior from students, including those who pay in cash or abruptly leave.

Moussaoui's laptop

Soon after Moussaoui's arrest, FBI agents in Minneapolis asked bureau headquarters to float his name in international intelligence circles. Within days, the French intelligence agency responded with sketchy information stating that Moussaoui had been under surveillance and might be associated with terrorists, a federal law enforcement official said. When the French were prodded for more details, they said that a friend of Moussaoui's had fought with Bin Laden in Chechnya, but did not tie Moussaoui to a specific terrorist group.

It could not be learned whether the FBI shared that information with the FAA.

When the Minneapolis agents asked headquarters to seek a FISA warrant, bureau lawyers told them that the evidence did not meet the law's test. Unlike a standard search warrant, which requires a belief that a crime already has been committed, FISA requires only that agents show it is more likely than not that a suspect is planning terrorist activities, is a member of a terrorist group or is an agent of a foreign power.

Washington lawyer Kenneth Bass, who helped write the FISA law as a Justice Department official during the Carter administration, said that a decision on a warrant in Moussaoui's case would rise or fall mainly on the credibility and strength of the foreign intelligence information.

But Schiavo, who handled FISA requests as a special assistant to Attorney General Richard Thornburgh in 1987 and 1988, contended that the FBI probably could have made a strong case even without the foreign intelligence.

She said that if the lawyers had laid out the circumstances of Moussaoui's flight training, including that he was a foreigner who paid with a large amount of cash, they could have shown "reasonable suspicion" and obtained a FISA warrant.

FBI Director Robert Mueller has said he believes bureau lawyers made the right decision on the Moussaoui warrant request, given what was known at the time.

Even after the Sept. 11 attacks, Minneapolis agents investigating Moussaoui were still seeking a FISA warrant.

Then, on about Sept. 14, an agent phoned a Pan Am official and asked about a computer disk that had been found next to Moussaoui's laptop and which contained a 747 flight manual, several people familiar with the case said. The Pan Am official said it must be "proprietary information" that belonged to the school.

It was too late to prevent the attacks. But the flight manual would help agents get a standard search warrant so they could begin to investigate whether Moussaoui was connected to the hijackers.

On the laptop's hard drive, they found voluminous information on crop-dusting planes -- aircraft that investigators fear could be used in a biological or chemical weapons attack. Alleged hijacker Atta made inquiries at a Florida crop-dusting firm early last year and again in the weeks before Sept. 11.