The hubbub raised over six Islamic imams being removed from a US Airways flight in Minneapolis for suspicious behavior is the latest in a string of incidents underlining one consistent thread in the war on terror: Muslim terrorists have never given up on the tried-and-true idea of hijacking airplanes and blowing them up to kill and demoralize the infidels.

Police and witness reports suggest a list of suspicious activities and remarks. Some of the imams were discussing in Arabic about "bin Laden" and condemning America for "killing Saddam." Imams asked for seat belt extenders for the extremely obese, for no apparent reason. (Did you know such extenders even existed?) The imams spread out at all exits of the plane, two in front, two in the middle, two in the rear. Between the six imams, they had one piece of checked luggage.

There have been some seriously frightening moments since 9-11. Just a few months later, foiled "shoe bomber" Richard Reid was arrested on board American Airlines Flight 63 from Paris to Miami for attempting to light explosives hidden in his shoes. In court, he declared his allegiance to Osama bin Laden and was convicted in 2003 and sentenced to life in prison.

On March 5, 2003, Fazal Karim, an illegal immigrant from Pakistan, attempted to board an American Airlines flight from Dallas to Houston when screeners found in his luggage 32 razor blades concealed within a box containing a coiled belt. He was convicted of attempting to conceal weapons and making false statements about his immigration status, and sentenced to five years in prison.

On June 29, 2004, journalist Annie Jacobsen complained about the very suspicious behavior of a group of Middle Easterners during a flight from Detroit to Los Angeles. When the plane landed, they were detained, and though the Department of Homeland Security would later report that they were a band of Syrian musicians en route to a gig in Las Vegas, Jacobsen learned that DHS also decided to classify the entire report. Why classify it if nothing was amiss?

On Aug. 10, British authorities thwarted a plot to simultaneously blow up 10 aircraft heading to the United States using explosives smuggled in luggage, averting what police described as "mass murder on an unimaginable scale." Some plotters had already purchased tickets on a flight to stage a test run, with an actual attack planned for days later.

The national media have certainly paid attention to airline security issues since 9-11. But they can't be expected to learn about and report every airline disruption, especially if no real act of terror occurs. Thus it begs the question: How many times, at how many airports, have there been these kinds of incidents that have not made it to the news desks? I ask because I've been a witness to one such incident, from a distance of perhaps three feet, which never made it on the news.

On Oct. 14, I was in Grand Rapids, having boarded United 5832 to Chicago. It was one of those smaller commuter jets with two seats on either side of the aisle. The flight was perhaps one-third full, giving sardined passengers the opportunity to move to the multiple open rows after the boarding process was complete. That's when I noticed the two men, one a younger Muslim, the second an older black man, make their way from the back to the two seats behind the bulkhead on the right side of the plane, one row in front and across from me.

Odd. If they wanted more breathing room, why were they choosing to sit together again in crammed quarters, given all the open rows? Why did they move at all? And if they remained together because they needed to visit, why didn't they exchange a single word? I watched them as they just sat, staring straight ahead. And the plane also just sat by the gate, for a good 15 minutes.

And then the hatch flew open and a half-dozen DHS/FBI agents rushed in, surrounded these two men and, flashing badges, ordered them off the plane.

Now stop for a minute. Imagine you were one of these two, and you were innocent. What would be your reaction if suddenly confronted by a small army of heat-packing federal agents demanding your removal? You might literally jump out of your seat in surprise. What? Me? Huh?! Why? What's going on?! What'd I do? What's the meaning of this? And the like. And that's when it really got creepy.

I watched as the two men stood up and, without a word, without a shred of emotion on their faces, calmly accompanied the agents off the plane. How else to explain this? They were expecting their detention.

The pilot would take to the intercom a few minutes later to explain what he could. Homeland Security had been running background checks on these two, and while nothing had registered on the computers, the flight crew was "just uncomfortable" -- as they had every reason to be.

Something is happening out there. And it's not good.