As 19 hijackers made their way along the concourses at three East Coast airports on Sept. 11, bent on executing the deadliest terrorist attack in history, they were subjecting the U.S. aviation security system to its most critical test.
At almost every step along the way, the system posed no challenge to the terrorists--not to their ability to purchase tickets, to pass security checkpoints while carrying knives and cutting implements nor to board aircraft.
The system worked the way it was intended, according to all the available evidence. For three decades, it has been preoccupied with looking for guns and explosives rather than for dangerous people. That, security experts and aviation professionals say, was its vulnerability. The terrorists did not breach the nation's airport security system; they slipped through its loopholes.
Nothing in Federal Aviation Administration rules and regulations--even assuming they were followed to the letter--would have prevented the hijackers from carrying out their baleful missions, considering what is known so far about the plot to hijack jetliners and suicide-dive them into the World Trade Center and the Pentagon.
"The absolute truth is I have not been informed of any breaches in security that took place on Sept. 11," said Susan Baer, general manager at Newark International Airport in New Jersey, where one of the hijacked planes took off. She echoed similar assessments by law enforcement and airline industry officials of the hijackers' success at also boarding planes at Boston and Virginia airports.
The governing assumption has long been that a hijacker's principal goal is to use the aircraft as a bargaining chip, whether for political purposes or to reach an unscheduled destination.
Until the very morning of Sept. 11, leaders of the security community had not focused on the threat that actually materialized: squads of lightly armed hijackers seizing airliners as instruments of suicide and destruction.
But an attack similar to this month's, if not on the same horrific scale, was not entirely unforeseen. On May 7, Brian Sullivan, a former FAA special agent at Logan International Airport in Boston, expressed his concerns in a letter to Sen. John F. Kerry (D-Mass.).
"What protection is there against a rogue terrorist? And with the concept of jihad, do you think it would be difficult for a determined terrorist to get on a plane and destroy himself and all other passengers? . . . With our current screening system, this is more than possible, almost likely."
Kerry passed the letter on to the General Accounting Office, the congressional investigative agency, which was examining security issues.
Why the nation's aviation security system failed to anticipate a threat that, in retrospect, might easily have been theorized by experts will weigh heavily on U.S. efforts to upgrade the security arsenal. Senate and House panels started that process last week.
Only Friday, Inspector General Kenneth M. Mead of the Transportation Department recommended to a House subcommittee that a federal agency or government entity should be entrusted with all screening of passengers, aviation employees, baggage and cargo; that it take over the Federal Air Marshal program (a small cadre of undercover officers who fly as passengers); and that it develop advanced security equipment.
Fighting the new threat requires radically different security systems, assumptions and even equipment, including new screening technologies that will subject passengers to unprecedented intrusiveness; changes in the interior construction of airliners and the operating procedures of cockpit crews confronted with disturbances; and much more aggressive profiling of passengers to identify potential terrorists.
But aviation experts say none of these measures will do much good if more fundamental flaws in the system aren't quickly repaired.
Indeed, one of the U.S. security system's principal weaknesses is that individual pieces of the overall program are uncoordinated, so that information gathered by one sector is not communicated to others. Although a little-known profiling program used by most U.S. carriers identifies potentially high-risk passengers, for example, gate agents are not required to subject those travelers to special scrutiny.
"To say no one can use a knife today even in an airport restaurant is to shut the door after the horse is gone," says Issy Boim, a former Israeli security official who worked for 17 years with El Al, that country's national air carrier. More crucial, he says, is designing counter-terrorism measures in a system of interlocking and complementary rings. "In aviation, there's no one solution."
A team of Times reporters has traced the paths of the 19 suspected hijackers through the nation's aviation security system as it existed before Sept. 11 and found:
* Airport security checkpoints, even if they did detect such weapons as small knives and cutting tools, typically did not consider these as threatening.