The revelation that two passengers aboard the Malaysia Airlines flight that vanished en route to Beijing were traveling with stolen passports is shining a light on a major vulnerability in airline security. That is the failure to screen hundreds of millions of international passengers for fraudulent or lost documents.
Checking a passport is as easy as pressing a button or picking up the phone, yet most countries don't.
There's a global clearinghouse for stolen or lost passports -- a database run by Interpol with more than 40 million travel documents.
But of the 1 billion people who fly internationally every year, four out of 10 - a full 40 percent - are never checked against it to see if they're traveling on false documents, even though the database costs nothing to check.
A total of 166 countries contribute information to the database, nearly tripling its size in the last seven years. But the vast majority doesn't routinely use it.
"This is not a complicated system in terms of accessing the data. What you have to have is some capital and resources put to this -- and then they have to use it, said CBS News security analyst Juan Zarate.
Zarate thinks not checking incoming passengers through Interpol's database is a glaring weakness in airline security. Malaysia had access to the database, yet the manifest on Flight 370 wasn't checked.
"There's no question the international system, the aviation security system, has to get better. There's no question the United States has become the gold standard in many ways. But the rest of the world has to catch up," Zarate said.
Interpol Secretary-General Ronald Noble has criticized the lack of widespread use by most countries of the agency's stolen and lost travel documents database, known as SLTD.
He told a security summit last month: "Only a handful of countries are systematically using SLTD to screen travelers. The result is a major gap in our global security apparatus that is left vulnerable to exploitation by criminals and terrorists."
Interpol says about 60,000 inquiries a year match a lost or stolen passport in the database. It is now working on a system that would airlines to prevent someone from using a stolen passenger number from even booking a ticket.