The report says that in early summer 2001 the hijackers took cross-country surveillance flights, that some also took additional practice flights, and that they made preparations for the attacks through flight training and related reconnaissance. It also states that Jarrah asked to fly the Hudson Corridor, a route past New York landmarks including the World Trade Center.

FAA and FBI records show that 4 of the 19 hijackers, one aboard each flight, received flight training, possessed FAA certificates as qualified pilots and honed their skills at flight simulator facilities.

In his EC, Williams wrote that he believed that there was a coordinated effort by Usama Bin Laden to send students to the United States to attend civil aviation universities and colleges.[2] ... Jay stated that ... the FBI was well aware that Bin Laden had individuals working for him with pilot training and that Middle Easterners commonly received flight training in the United States.[2] The OIG report reviews "allegations that the FBI failed to act prior to September 11, 2001, on intelligence information that warned of potential terrorists training in aviation-related fields of study in the United States" and that there were "other pieces of intelligence information prior to September 11 that indicated connections between persons of interest to the FBI and airplanes or flight schools."[2]

The FBI’s January 2000 "Strategy for Addressing Future Terrorist Attacks" noted that "terrorists are increasingly employing new, advanced technology and tactics." It described the Bojinka plot and stated that "The use of aircraft as weapons in a terrorist attack... is a new modus operandi which must be addressed."[11] The report also notes that, "information on the FBI’s effort in 1998 to assess the potential use of flight training by terrorists and the Phoenix electronic communication of 2001 warning of radical Middle Easterners attending flight school were not passed to FAA headquarters."[11] Of the Phoenix memo itself, the Commission recounts Williams’s warning "of the possibility of a coordinated effort by Usama Bin Laden to send students to the United States to attend civil aviation universities and colleges" and that it was sent to FBI headquarters and New York agents but "was not seen by leadership at the FBI, CIA, or the Department of Justice until after the attacks."[11]

The report states that the CIA alerted Malaysian authorities about a planned meeting of Muslim militants in Kuala Lumpur in January 2000 after intercepting calls from the Yemen Safe House, and that the significance of this meeting was only recognized after the USS Cole attack nine months later. Three men photographed in Malaysia are now believed to have been involved in the Cole attack, and two of those three later became among the 19 September 11 hijackers.

Williams noted that "an inordinate number of individuals of investigative interest" were attending civil aviation training at schools in Arizona.[1] He expressed his suspicion that this was an effort by Usama Bin Ladin to establish a cadre of individuals in civil aviation who would conduct future terrorist activity.[1] The Joint Inquiry report cites the Phoenix memo as pre‑9/11 intelligence relating to civil aviation training and discusses how it was not effectively acted upon at higher levels.[1]

Moussaoui had been taking flight lessons at the Airman Flight School in Norman, Oklahoma, since February but stopped in late May.[5] The Commission later concluded that agencies had failed to "link[] the arrest of Zacarias Moussaoui, described as interested in flight training for the purpose of using an airplane in a terrorist act, to the heightened indications of attack" before September 11.[6] These passages describe FBI awareness of an individual taking flight lessons with apparent terrorist intent prior to 9/11 and criticize the failure to connect that information to the broader threat.[5][6]

The FBI did know that after the 1993 World Trade Center bombing, a participant in the plot had been a student who had overstayed his visa, and the Department of Justice asked INS to devise a better way to track students.[2] INS "scraped together $10 million and piloted a successful student tracking program in the Atlanta area in June 1997, which included a flight school."[2] Staff Statement No. 1 further notes that "before 9/11, the FBI and CIA did know of some of the practices employed by al Qaeda" from training manuals and interrogations, but despite scattered knowledge, "the system did not work" to integrate and act on these pieces of information.[2]

A computer used by Yousef and interrogations of another terrorist who lived with him in Manila revealed that several Middle Eastern pilots were training at American flight schools. At least one had proposed hijacking a plane to crash into federal buildings.

Among the information gathered from Yousef's captured laptop and subsequent interrogations was that several Middle Eastern pilots were in the process of training in U.S. flight schools. At least one of the pilots had already proposed flying hijacked planes into federal buildings.

"The FBI also learned that these individuals were receiving firearms and martial arts training in the New York area, and the FBI began to surveil these firearms training sessions. The FBI had an informant with access to the cell but, in essence, deactivated him shortly before the bombing. However, there was no indication of the magnitude of the attack they were planning or that they intended to kill thousands of Americans." This testimony describes FBI surveillance and informant use around the 1993 WTC bombing cell, but does not mention flying lessons, aviation recruiting, or surveillance flights prior to 9/11.

The commission found that the key pre‑September 11 failure at the CIA was its not adding to the State Department’s “watch list” two of the “muscle” hijackers ... the suspected al‑Qaeda militants Nawaf al‑Hazmi and Khalid al‑Mihdhar.[4] The CIA had been tracking Hazmi and Mihdhar since they attended a terrorist summit meeting in Kuala Lumpur, Malaysia, on January 5, 2000.[4] Under their real names they rented an apartment, obtained driver’s licenses, opened bank accounts, purchased a car, and took flight lessons at a local school; Mihdhar even listed his name in the local phone directory.[4] The CIA inspector general concluded that informing the FBI and good operational follow‑through ... might have resulted in surveillance of both al‑Mihdhar and al‑Hazmi, which "would have had the potential to yield information on flight training, financing, and links to others who were complicit in the 9/11 attacks."[4]

"The Phoenix EC was a memorandum sent by an agent in the FBI’s Phoenix office in July 2001 to FBI Headquarters and to the FBI’s New York Field Office. The Phoenix EC outlined the agent’s theory that there was a coordinated effort by Usama Bin Laden to send students to the United States to attend civil aviation universities and colleges for the purpose of obtaining jobs in the civil aviation industry to conduct terrorist activity." The report further notes that this intelligence came in 2001 and concerned possible Bin Laden-linked students at civil aviation schools, not specifically individuals involved in the 1993 WTC bombing, and that the FBI did not fully act on this information before 9/11.

The report outlines what was known about the threat of terrorism before the September 11th attacks occurred, tracing the flow of intelligence back to the World Trade Center bombing of February 1993.[9] It details how the plot unfolded, what the intelligence community knew, and how agencies such as the FBI and CIA handled information about al Qaeda and its operatives between the 1993 bombing and the 2001 attacks.[9] This executive summary frames the pre‑9/11 intelligence context, including the handling of information on al Qaeda operatives, but does not state that 1993 WTC bombers later took flight training while under CIA/FBI surveillance.[9]

"Two months before the suicide hijackings, an FBI agent in Arizona alerted Washington headquarters that several Middle Easterners were training at a U.S. aviation school and recommended contacting other schools nationwide where Arabs might be studying." The story notes: "None of the Middle Eastern men identified by the Arizona counterterrorism agents or any information contained in their July 2001 memo pointed to the suicide plot that leveled the World Trade Center and killed thousands in New York, Washington and Pennsylvania, officials said. 'None of the people identified by Phoenix are connected to the Sept. 11 attacks,' FBI Assistant Director John Collingwood said." This article describes FBI awareness of Middle Easterners in flight training in 2001, but explicitly states they were not linked to the 9/11 hijackers and does not tie them to the 1993 WTC bombers.

The 9/11 Commission report found that the intelligence community had a "significant increase" of intelligence information regarding Osama bin Laden and a potential terrorist attack, but that the community "too often failed to focus on that information and to capitalize on available and potentially important information."[8] "Did the FBI miss clues prior to September 11? Yes."[8] The FBI failed to connect the Moussaoui case to a July 2001 memo from Phoenix FBI agent Kenneth Williams warning that Arab men who might be linked to Osama bin Laden were training at a flight school in Arizona.[8] The CFR summary underscores that intelligence agencies had clues about terrorists in flight schools and did not effectively act on or integrate them, but it does not report that individuals involved in the 1993 WTC bombing were the ones taking lessons.[8]

Some mainstream media reports have conflicted with these statements, claiming that the FBI, CIA and Executive Branch knew of the threat of planes being used as missiles as early as 1995, following the foiling of the Bojinka plot.[11] It cites one account claiming "The FBI had advance indications of plans to hijack U.S. airliners and use them as weapons, but neither acted on them nor distributed the intelligence to local police agencies."[11] The article notes that the Joint Inquiry of 2002 confirmed that the Intelligence Community had received at least twelve reports over a seven‑year period suggesting that terrorists might use planes as weapons, and that the CIA disseminated several of these reports to the FBI and FAA, but no assessment of likelihood was produced and U.S. policymakers remained unaware.[11] This page discusses claims of advance knowledge and failure to act, but does not document that specific individuals from the 1993 WTC bombing took flying lessons under CIA/FBI observation.[11]

Other reporting also indicates possible surveillance activity in New York before 9/11 that was considered of sufficient concern that it was included in a Presidential Daily Brief in August 2001 addressing bin Laden's intention to attack the United States. Relying on open source intelligence, Khalid compiled data from Western aviation magazines, telephone directories for U.S. cities, airline timetables, and conducted Internet searches on U.S. flight schools.

"Pellegrino had been assigned by the FBI to investigate the 1993 bombing of the World Trade Center. That was where Mohammed's name first came to the attention of US authorities because he had made a money transfer to one of those involved." The article describes how Khalid Sheikh Mohammed later became known as the alleged '9/11 mastermind', and that his name surfaced during the 1993 WTC investigation, but it does not state that he or other 1993 bombers were known to be taking flying lessons, recruiting pilots, or conducting surveillance flights before 9/11.

The overriding conclusion was that the government’s principal failure in 9/11 was a failure to "connect the dots."[3] "However, what brought him to the attention of the FBI—taking flight lessons for the purpose of using an airplane for an attack (he had no interest in learning to land the plane)—was not passed up the chain of command and not linked to the possibility of a broader plot."[3] This Brookings article refers to the Moussaoui case and describes how information about his flight training and possible intent was not effectively used, but it does not associate this with perpetrators of the 1993 WTC bombing.[3]

The article notes that "Somewhere in CIA there was information that two known al-Qaeda terrorists had come into the United States. Somewhere in the FBI, there was information that strange things had been going on at flight schools in the United States."[6] It describes the Phoenix memo: "Also in July, a Phoenix-based FBI agent sent a message to FBI headquarters, Alec Station, and FBI agents in New York alerting them to 'the possibility of a coordinated effort by Osama bin Laden to send students to the United States to attend civil aviation universities and colleges.'"[6] The agent suggested interviewing flight school managers and identifying all Arab students seeking flight training; the memo was not seen by top leadership until after 9/11.[6]

The attack was planned by a group of terrorists including Yousef, Ahmed Ajaj, Mahmud Abouhalima, Mohammed A. Salameh, Eyad Ismoil, Nidal Ayyad, and Abdul Rahman Yasin.

Before the attacks, the various hijackers moved to and lived in the U.S. while making their preparations. Some took flight training courses to prepare for piloting the planes after they would be hijacked, and others were "muscle" hijackers who would assist them.

"Prior to the 9/11 attacks on the World Trade Center and the Pentagon, terrorist hijackers enrolled in flight training schools in the U.S. Some of the hijackers participated in extensive flight simulator training and learned how to fly jetliners over major U.S. cities. Oddly enough, these eventual hijackers told flight instructors they only wanted to receive simulator training on flying over major metropolitan areas, such as Washington, D.C. and New York City. The hijackers expressed absolutely no interest in learning to take off or land the jumbo jets they claimed to want to fly professionally." This Defense Logistics Agency document describes suspicious behavior of the 9/11 hijackers at flight schools, but it does not mention 1993 WTC bombing participants nor CIA/FBI knowledge about them taking flying lessons before 9/11.

This entry on "September 11 intelligence before the attacks" notes that "In December 1998, the CIA's Counterterrorist Center reported to President Bill Clinton that al-Qaeda was preparing for attacks in the U.S. that might include hijacking aircraft."[13] It also recounts that on July 10, 2001, "FBI Special Agent Kenneth Williams sent a letter to FBI headquarters warning of suspects connected to al-Qaeda who were attending flight schools in Arizona, and demanding further investigation," known as the Phoenix Memo.[13] The article emphasizes that since 1999, "information about the hijackers and the preparations for the eventual attack already held by the NSA and the CIA wasn't passed to the FBI until August 2001," largely due to inter‑agency communication lapses.[13]

"Several 1993 WTC bombing suspects were linked to New York City's Al Kifah Center -- part of the Pakistan-based Office of Services which recruited and trained volunteers to fight the jihad against the Soviets in Afghanistan." This chapter notes that the FBI monitored and investigated the Al Kifah Center and related networks in connection with the WTC bombing, but it focuses on recruitment for jihad in Afghanistan and does not reference flying lessons, aviation industry recruitment, or surveillance flights in the run-up to 9/11.

The "Planning of the September 11 attacks" entry explains that in 2001 Zacarias Moussaoui received flight training at Pan Am International Flight Academy in Phoenix, Arizona, from January to March.[12] It quotes directly from the Phoenix communication: "The purpose of this communication is to advise the Bureau and [its agents in] New York of the possibility of a coordinated effort by USAMA-BIN-LADEN (UBL) to send students to the United States to attend civil aviation universities and colleges. [The FBI in] Phoenix has observed an inordinate number of individuals of investigative interest who are attending or who have attended civil aviation universities and colleges in the State of Arizona."[12] The entry states that Williams’s memo "was not seen by leadership at the FBI, CIA, or Department of Justice until after the attacks."[12]

The FBI was able to identify the perpetrators of the attack as radical Islamists who were followers of the "Blind Sheikh," Omar Abdel Rahman. Later in 1993, the FBI disrupted the "Day of Terror" plot ... The FBI was able to prevent this attack by reactivating a source who had previously infiltrated this particular cell.

"The 19 men who hijacked and crashed the four planes were all trained by al Qaeda. Three of the suspected pilots—Mohamed Atta, Marwan Al-Shehhi, and Ziad Jarrah—were part of an al Qaeda cell based in Hamburg, Germany. All four pilots took flying lessons in the United States." The official FBI case history confirms that the 9/11 hijackers received flight training, but it does not mention any CIA or FBI prior knowledge of 1993 WTC bombers taking flying lessons, recruiting pilots, or conducting surveillance flights before 9/11.

The document argues that "The FBI and CIA knew that Muslim terrorists were training as pilots in America, some of them at US Armed Forces Training Schools" and that "security services knew that an attack against the World Trade Center was imminent" as of August 2001.[7] It further claims that "As of early September, security services, including the FBI, knew that an attack would take place in New York on September 11" and that "those who could have acted to avert the attacks were actively prevented from doing so by the government."[7] These assertions attempt to establish extensive prior knowledge and inaction by U.S. agencies, but are presented as advocacy and do not provide official documentary proof linking the 1993 WTC bombers to pre‑9/11 flight training under CIA/FBI observation.[7]

This secondary compilation cites an FBI chronology noting that in 2001 Arizona agents George Piro and Ken Williams visited a Phoenix flight school to see if any suspicious students had attended it recently; the manager "immediately informs them about Hani Hanjour, one of the alleged hijackers of Flight 77."[9] The same document cross‑references the 1993 World Trade Center bombing and other plots in an event matrix, but does not indicate that 1993 WTC bombers themselves were known by the FBI or CIA to be taking flying lessons before 9/11.[9] It situates Hanjour’s earlier time at the Arizona flight school as part of the broader timeline of pre‑9/11 intelligence leads regarding flight training.[9]

This summary reproduces and comments on a Washington Post report that "Federal authorities have been aware for years that suspected terrorists with ties to Osama bin Laden were receiving flight training at schools in the United States and abroad" and that "law enforcement officials were aware that fewer than a dozen people with links to bin Laden had attended U.S. flight schools."[3] The cited reporting notes that there was "no information to indicate the flight students had been planning suicide hijacking attacks" but confirms pre‑9/11 awareness of terrorist-linked individuals in flight training.[3] It also references court testimony and press reports indicating that the 19 suspected 9/11 hijackers had received flight training at at least 10 U.S. flight schools.[3]

The National Commission on Terrorist Attacks Upon the United States (9/11 Commission) report traces "what was known about the threat of terrorism before the September 11th attacks occurred, tracing the flow of intelligence back to the World Trade Center bombing of February 1993."[9] It describes how al Qaeda evolved after the 1993 bombing, what information various agencies had about al Qaeda operatives, and the failures in using that information, but does not state that individuals involved in the 1993 WTC bombing were later observed by CIA or FBI taking flight lessons, recruiting, or conducting surveillance flights in the United States.[9]

A Reddit comment discussing 9/11 claims: "The CIA, and the Mossad, and the Lebanese Secret Service as far as I heard - both of them reported to their American counterparts at some point. The FBI also knew because a bunch of flight instructors reported Muslim men who wanted to learn how to fly but not how to land." The same thread quotes an official description of the Moussaoui case: "On August 15, 2001, the flight school reported its suspicions about Moussaoui to the FBI, including that he only wanted to learn how to take off and land the airplane, that he had no background in aviation, and that he had paid in cash for the course." This user-generated discussion references known pre-9/11 flight school warnings but does not provide evidence that CIA or FBI knew individuals involved in the 1993 WTC bombing were taking flying lessons or recruiting pilots.

The background article on "Responsibility for the September 11 attacks" notes that CIA operatives monitored the movements of known militants Khalid al-Mihdhar and Nawaf al-Hazmi when they visited the U.S. but "did not notify the FBI or gain an inkling of what the hijackers were planning."[5] It further recounts that during cross-examination in the 2006 Moussaoui trial, FBI agents stated that "the bureau was aware, years before the attacks in 2001, that al-Qaeda planned to use planes to destroy important buildings."[5] The entry, however, does not attribute any pre‑9/11 FBI or CIA knowledge specifically to individuals involved in the 1993 World Trade Center bombing taking flying lessons or performing surveillance flights.[5]

The perpetrators' intent was to punish and seek revenge for the United States' support of Israel.