I hate to be Mr. Cost/Benefit Analysis, but someone needs to mention it.

Most articles I've read mention a definite false positive problem with the CTX/Invision scanners for luggage, usually rumored to be about 23% of all bags scanned.

Over one billion suitcases were checked last year in the US. Imagine how difficult positive bag matching would be to achieve if we scanned all suitcases: upwards of 230 million bags would need to be hand-searched because they set off the alarm (but contain no explosive).

At the often-mentioned capacity of 150 bags an hour, that's 35 bags an hour (per machine) that need intense searches. My checked bags are full, not empty, and would require at least 10 minutes to search and repack. Ever see the Lucy episode where she can't keep up with the machine?

If those numbers are valid, every hour of scanning would produce maybe six hours worth of hand-screening. Yikes!!

Next, let's see how many of these "Wolf, Wolf, Everywhere a Wolf" machines we would need. At max capacity, each machine could look at about 1,314,000 bags annually.

Problem is, the bulk of departures take place during the daytime 12 hours, not all 24.

A conservative estimate would require about 3000 of these scanners to handle peak traffic times. At stated prices, about $5 billion just for the machines. Not counting the labor to route the bags through, run the scanner and do the hand-searching. All of whom, I presume, have to be expensive federal employees, just like customs agents, most people say.

Is it all worth it?

If exploding airplanes were common, most certainly, YES.

But what if there aren't any bombs? For 20 or 30 years? Is all this effort still worth it?

It's not that I relish a mid-air explosion and the certain death accompanying same; I'm just not afraid of the possibility as are some people. And no, I'm not sure I'd be willing to charge every passenger $10 each forever to look for the non-existent (or really rare) bogeyman.

A better answer? Selective screening of bags belonging to those people most likely to be a threat, starting with:

One-way tickets bought for cash by illegal aliens.

Effective security will mean concentrating the efforts on the most likely terrorists, not the chairman of Intel and not me.

Bring on the "I'm proud to be an American" frequent flier expedited security screening pass; I'll take one, leaving the security people more time to look for Atta's friends.

Every minute spent looking through my kid's backpack looking for legal items (but recently banned by FAA) is time not available to prevent another 9/11. As Ann Coulter pointed out that week in her column, how many hijackers were stopped by all of our security efforts that day? Any?

How many more hijackings would we have if we simply let people get on planes without all of the silliness?

I feel for all the people gripped with fear who think the answer is any more than the four in September. There isn't a hijacker behind every pair of cuticle scissors.