How Terrorism Has Changed Air Travel and Security Terrorist attacks and attempts prompt authorities to adjust airline security.

Dec. 27, 2009  -- The security routine has become just another part of flying these days: We take off our shoes, remove our belts and empty our pockets. The TSA inspects our toiletries.

Now, thanks to the latest apparent very close call aboard a Northwest Airlines flight on Christmas day, there's more to come.

Nigerian Umar Farouk Abdulmutallab, the Northwest Airlines bombing suspect, allegedly had explosives sewn into his underwear powerful enough to bring down the aircraft. The materials went undetected by airport security, and it's only because of a failed detonator that the passengers and crew survived.

So they didn't check his underwear.

Well, obviously. They don't check anybody's underwear. At least not the way they check, say, shoes. Even for those many thousands of us who are made to assume the position for random body scan, the TSA inquiry doesn't go fully private. For which all of us, no doubt, are relieved.

Or, at least, we were. Because what if that guy succeeded? Somewhere, right now, someone in authority has got to be considering yet another adjustment to the screening process.

In fact, they already have. Expect more security pat-downs and scrutiny before reaching the plane's gate. International travelers will be confined to their seats for the last hour of flights. They're even going to limit personal items that can be in passengers' laps.

Everyone seems to know about it from the movies and television, but there probably aren't many passengers left anymore who actually experienced air travel when men wore ties and the encumbrances of security were completely non-existent.

"Please fasten your seat belt."

That's as intrusive as it got -- until the hijacking era, when terrorists began leading us through a series of lessons on where the holes are, and we followed.

On Sept. 6, 1970, Palestinian hijackers attempted to take control of three airplanes and land them in the desert in Jordan. Days later, during a tense standoff, the hijackers blew up the aircraft after removing the passengers.

The burned plane was the visual culmination of nearly a decade of gunmen commandeering aircraft as bargaining chips or simply to get somewhere. This is why metal detectors came in to wide use for good.

Security Measures Chase Terrorists' Imaginations

The 1980s brought another change to air travel.

Pan-Am Flight 103 exploded over Scotland after leaving Heathrow Airport en route to New York. A bomb hidden inside a radio in a piece of checked baggage brought down the plane.

Since then, all baggage has been electronically screened, and it's why you take your laptop out of your bag before it goes through the scanner.

And then there was Sept. 11, 2001. The hijackers were able to gain control of the planes because they were able to access the cockpit and kill the pilots, flying the planes into the World Trade Center towers, the Pentagon and a field in rural Pennsylvania. It was the most devastating terrorist attack on U.S. soil.

Now, all cockpits have reinforced doors.

Thank Richard Reid when you take your shoes off in the airport security line. In December 2001, he a concealed a bomb in his shoes that was packed with enough explosives to blow a hole in the plane. Fellow passengers on American Airlines Flight 63 from Paris to Miami witnessed his failed attempt to ignite a fuse poking out of his shoe and subdued him.

In 2006, an undercover British agent thwarted the plans of a terror group to blow up planes bound for the U.S. from Britain. The terrorists intended to mix a sports drink with a gel-like substance that could explode when ignited by a cell phone or mp3 player.

So now they take the drink bottles away from all of us, and there's the maximum-three-ounces-of-liquid rule.

But bombs sewn into clothing -- bombs sewn into undergarments, of all things? How far can they take the process of going over the rest of us?

Kip Hawley, head of the TSA during the Bush administration sees only one solution.

"The long term answers -- I don't see any way around it -- are the body scans that will detect whatever you have beneath your clothes," he said.

The worrying thing is being always one step behind.

But that's what happens when you're chasing the imagination of terrorists, which always are looking for the holes and finding them often before we do.