Over 800 Received Last Year, Terrorism Experts Say : Tips Failed to Halt Aircraft Attacks

Sometimes they are calls phoned directly to airline offices. More often, they are tip-offs relayed from operatives and allies through international intelligence networks.

Altogether, U.S. intelligence received roughly 800 warnings about potential terrorist attacks on airports and airlines last year, according to counterterrorism and congressional sources. And not one, they said, enabled them to predict a subsequent bombing, hijacking or sabotage attempt.

Indeed, counterterrorism officials concede, the U.S. warnings system, now at the center of heated controversy, has so far failed to prevent or to accurately predict a single international incident since terrorism became a weapon of modern warfare in the late 1960s.

“When you look at aircraft hijackings and bombings over the last five years--Air India, Air Egypt, TWA, Pan Am, KAL--there was no warning on any,” according to an airline executive familiar with security.

German authorities passed along a warning last November, based on the arrest of Middle East terrorists, that a Toshiba radio-cassette player might be used to conceal a bomb and just such a bomb is believed to have destroyed Pan Am Flight 103 from London to New York on Dec. 21. But the German warning, say counterterrorism officials, was too general to predict the disaster.

No Alternative

While the U.S. warning system and its methodology are coming under increasing scrutiny, both supporters and critics say that there is, for now, no alternative.

“You can’t ignore any threat, no matter how unlikely it seems. That might just be the one that is for real,” said a counterterrorism official. “And preventing only one makes the whole effort worth it.”

Recent threats have ranged from crank calls to serious data from friendly intelligence agencies. Most are provided by human intelligence. Few threats are picked up by electronic intercepts or spy technology, according to counterterrorism officials.

“The crank calls are filtered out pretty quickly, although they are still investigated as far as is possible,” said a Bush Administration source. Of the 800 or so threats received last year, fewer than 5% were forwarded to the airlines.

In the period between January, 1988, and February, 1989, the Federal Aviation Administration issued only 33 official warnings. More recently, on March 16, the FAA issued an advisory about three Palestinians attempting to hijack an American aircraft in Europe, a warning that originated with Jordanian intelligence.

Congressional Investigation

The efficiency of the operation that leads to official warnings is now being investigated by the House Government Operations subcommittee on transportation.

Counterterrorism sources said that the magnitude of the job is overwhelming. In recent briefings for congressional staff aides, FAA officials said that U.S. intelligence sorted through about 17,000 pieces of information in analyzing last year’s threats.

Counterterrorism officials not only investigate tips but also analyze trends among extremist groups and individuals. Warnings already have been issued this year based on the trial here of Fawaz Younis, who was convicted earlier this month of the 1985 hijacking of a Jordanian aircraft, and the April 15 anniversary of the 1985 U.S. air raid on Libya.

One congressional aide complained that the pattern of warnings over the last year “looks like a terrorist calendar. There’s too much about past anniversaries and too little about what’s going on now out there.”

A special CIA counterterrorism team analyzes all threats involving foreign sites and groups based on three main criteria: the reliability of the source, the credibility or plausibility of the information and the specificity of the claim.

Threat Met Criteria

The March 16 threat became an official FAA warning because it received high ratings on all three counts. Jordanian intelligence has established a strong record of reliability. An incident was plausible because of the coming Easter weekend and last December’s Pan Am bombing. And the information contained specific names as well as several possible aliases.

Many threats ultimately are dismissed. Despite the eerie prescience of the threat against Pan Am that was relayed by an Arab national living in Helsinki shortly before the Dec. 21 Pan Am bombing, authorities eventually judged it to be a hoax largely because of the source, U.S. officials said. The same source earlier had passed along alleged intelligence to Israel about an impending attack, and that warning proved to be false.

U.S. authorities have assigned unofficial ratings to foreign intelligence agencies. Data from Italy, for example, is often discounted “because Italian sources are notoriously bad,” said a counterterrorism official.

Despite Israeli intelligence’s legendary reputation, tips from Jerusalem are not automatically passed along.

“We know that Israel and other countries have their own agendas and sometimes they are manipulative,” he said.

The sifting process, however, is not scientific, counterterrorism officials concede.

‘Too Little Solid Information’

“There’s usually too little solid information,” he said. “A lot depends on what the regional analysts conclude.”

Congressional sources are concerned about the methodology.

“Fire stations get alarms ranging from one bell to nine,” he said. “Military alerts have degrees up to red. We need a similar system to be able to tell these threats apart.”

A security director from a U.S. airline said that some of the information forwarded to the airlines appears designed to provide cover for the intelligence agencies in case of a subsequent terrorist incident.

“We’re unable to evaluate that,” he said. “It will say: ‘This information is credible but has not been independently substantiated.’ That’s really not valuable information. Our security has no choice but to disseminate threat information it gets from the government.”

A Bush Administration official, acknowledging the criticism, countered: “We welcome anyone who has a better idea, under our circumstances, of how to analyze threats. The old adage applies: We have to be right all the time. Terrorists have to make it work only once.”

Times staff writer Douglas Jehl contributed to this article.