Terror link to Air France crash?

Could it have been terrorists, after all, who brought down Air France Flight 447?

French news reports that Airbus 330-200's passenger manifest contained the names of two people with alleged ties to Al Qaeda has renewed the focus on terrorism as a possible key to the puzzle of what brought the plane down more than a week ago on a flight from Rio de Janeiro to Paris.

A French nuclear submarine has now joined the search effort in the Atlantic Ocean for more wreckage and the black boxes, which hold the most crucial clues to the events of that stormy night. Speculation initially centered on lightning or turbulence as the cause of the plane crash, and later, on the potential malfunction of small speed sensors called "Pitot" tubes, which could have iced up leading to improper speed readings.

The focus on technical problems has been, in part, because almost immediately after the plane disappeared with 228 people aboard, the French authorities reportedly ruled out terrorism as a possible cause. That puzzled many aviation analysts, since so little was known at the time about the cause of the disappearance.

Since then, several clues have emerged that have prompted investigators to take another look at terrorism. First, a Spanish pilot flying in the same area reported he saw a "bright white flash" in the sky that evening. That could indicate a midair explosion of some kind. Air France also confirmed that it had received a bomb threat at its offices in Argentina four days before the crash. And now, there are the reports that the passengers included two people whose names match those on France's terrorist watch list.

But terrorism experts warn against jumping to any conclusions.

"Terrorist watch lists are notoriously unreliable. They're broad-brush, they cast a wide net, and we should not automatically conclude because those names popped up [on the passenger list] that those people were on the plane," says Andrew Thomas, an aviation security expert at the University of Akron in Ohio. "We've seen countless cases of mistaken identities, especially with Muslim names."

Mr. Thomas says it's just too early to rule terrorism in or out. No terrorist organization has claimed responsibility for bringing the plane down, and intelligence agencies have not reported any increase in "chatter" from their electronic surveillance of terrorist groups prior to the crash that would have indicated an imminent attack. Prior to 9/11, such chatter had increased significantly.

However, Al Qaeda did not take responsibility for the 9/11 attacks for months afterward. That's not unusual, says Thomas. No one claimed responsibility immediately after the downing of Pan Am Flight 103 over Lockerbie, Scotland in 1988. A Libyan national was later convicted of conspiracy to plant a bomb on the plane and is serving a life sentence.

"It's not unusual for there not to be an immediate claim," says Thomas. "Still, I'd temper all speculation until the black boxes are found."