If you want to board a commercial airliner anywhere in the world, you can expect pretty much the usual drill: Show identification and boarding pass, empty your pockets, step through an X-ray machine or scanner, maybe undergo a pat-down. But in many places, an elementary requirement gets skipped. No one will bother to check to see if you're actually the person you claim to be.
That failure may or may not have something to do with the shocking and mysterious disappearance of a Malaysia Airlines flight bound from Kuala Lumpur to Beijing on Saturday. As of Monday evening, authorities still didn't know what happened to the plane or the 239 people it was carrying. It seemingly vanished in midair.
But they do know one thing: At least two people on the flight had boarded using stolen passports, one from an Italian man and the other from an Austrian. Interpol, an international police agency whose members include 190 countries, is investigating whether any other passengers may have done the same thing.
Interpol says many countries don't make a habit of checking passenger names against its list of more than 40 million lost or stolen passports, making air carriers vulnerable to impostors. Last year, it says, there were more than a billion boardings by passengers whose passports were not screened in this way.
The United States is one of the commendable exceptions. Interpol says the U.S. uses the system to screen passports 250 million times a year. In 2011, the Department of Homeland Security was able to alert airlines to some 3,600 suspect travelers.
The United Kingdom and the United Arab Emirates are also heavy users of the list. But "only a handful of countries worldwide are taking care to make sure that persons possessing stolen passports are not boarding international flights," Interpol Secretary General Ronald Noble said.
It's hard to see why every government shouldn't insist on routine use of this basic protection. Terrorists certainly have reason to use stolen passports to evade detection: One who did is Ramzi Yousef, who took part in the 1993 bombing of the World Trade Center. Other criminals might also have strong motives to use false identities.
The passengers who did so to board this flight may not have been dangerous to their fellow travelers. But no one steals and uses someone else's passport for legitimate reasons. Only those who are inclined to violate the law and want to get away with it are given to this practice.
So there is no obvious reason why carriers shouldn't take the trouble to verify the identity of every person they transport. Any additional cost is bound to be trivial compared with that of the other security procedures established in the wake of the 9/11 attacks - or compared with the carnage and expense of a destroyed jetliner.
Whether the travelers who used stolen passports played any role in the fate of the plane is not known and may never be known. But had Malaysia Airlines conducted a simple check, there would be no possibility of it.
So why would any government wait to eliminate the possibility? The world can act now to close off this avenue for terrorists. Or it can wait until after one of them makes use of it.