Only a week ago the United States tightened security at the nation's airports in preparation for the summer Olympics in Atlanta.
Is the vigilance enough?
The question is reverberating throughout the nation again in the wake of the mid-air explosion of TWA Flight 800. Although there was no official indication at press time that the crash was caused by a bomb, airport security has suddenly reemerged as a top concern as a result of the speculation.
"Until we get this thing sorted, it is clear we have to pay more attention to airport security," says Michael Dobkowski, a terrorism expert at William Smith College in Geneva, N.Y. But he adds: "I am not confident that we can ever make airports immune from terrorism."
Despite those reservations, the Federal Aviation Administration (FAA) is trying to do just that. After the bombing of Pan Am Flight 103 over Lockerbie, Scotland, the FAA began a search for new technologies that could spot bombs in luggage. Just this year, new devices that can spot bombs were installed in Atlanta and San Francisco.
But Invision Technologies of Foster City, Calif., the manufacturer of the $900,000 machines, says US airlines are slow to buy them.
"The entire system could be protected for a small additional fee of, say, $2 per bag," says company president Sergio Magistri. "It's a money thing - the companies say the additional fee will make them noncompetitive."
Instead, the devices are being shipped overseas where governments are responsible for security. The new machines, which are based on the medical CATSCAN technology, scan luggage after it has been checked at the counter. They are in use in the Philippines, Israel, Japan, Brussels, and Britain.
Until the machines become more widespread in the US, flyers can expect increased visual inspection and possibly airport delays. The FAA moved all airports to a "3 plus" rating last week. The highest security rating is a 4. But an FAA spokeswoman would not disclose the specifics of the agency's security adjustments.
Since August 1995, increased security measures have been in place in all major airports. Passengers must show photo identification and are asked if anyone has given them any package or luggage to carry onto the plane.
Passengers are also warned not to leave luggage in terminals, and airports have instituted parking and unloading restrictions.
"There are other measures still that are not noticeable to those working or traveling," says the FAA spokeswoman. "But, of course, we don't disclose all of our measures to the public."
Still, there have been recent questions raised about how good the security is. On Wednesday night, former Transportation Department Inspector General Mary Schiavo told CNN that in recent tests her staff was able to penetrate airport security 40 percent of the time.
The TWA flight originated in Athens, Greece, which used to be considered a security risk. But security has been tightened. In May, an FAA team visited Athens's Hellenikon International Airport and determined its security measures were adequate.
The US Department of Transportation lifted a warning about lax security there. But a former CIA analyst who also worked on the Lockerbie bomb investigation termed it "unlikely" but "conceivable" that a bomb was placed on the TWA flight in Greece.
The flight was on the ground three hours Wednesday evening in New York before departing for Paris. Residents on eastern Long Island reported seeing a small flash followed by a much brighter flash. Then there was a loud explosion that some people thought was a sonic boom. The plane then spiraled into the water.
Airline safety experts cautioned against jumping to conclusions. "We ought to be careful about speculating about terrorism," says Vernon Grose, a former member of the National Transportation Safety Board on CNN. Jim Hall, the chairman of the NTSB, echoed this view. "It's irresponsible to speculate on the cause of this accident," he says.
But Mr. Dobkowksi says there is a "growing list of terrorist organizations that may have been involved."
He notes that there is even more attention focused on the US with the Olympic Games. In Atlanta, officials of the Olympics said there is no indication the explosion was connected to the Games, which start today.
Although it's possible that the TWA explosion was caused by some malfunction, aviation experts are inclined to believe it was caused by a powerful explosion.
"Even oxygen canisters couldn't do that," says Morton Beyer, an airline analyst in Washington. Oxygen canisters that heated up are considered the reason the ValuJet flight from Miami crashed in May.