Progress is prompted by problems, and the huge airport backups and delays caused by the British bust of alleged terrorists have security experts considering new screening techniques.

It should be noted that none of those arrested actually made it through security and boarded a plane. But if the police are right, the accused terrorists had a chillingly clever plan — bomb components disguised as innocent liquids that could be assembled on board and detonated in flight.

One screening technique being considered is the most obvious, but politically sensitive — passenger profiling. If the passenger fits a certain template — a Muslim male European of immigrant origin, as the British suspects were — it makes sense that they would be singled out for extra screening.

Yet political correctness dictates that such extra screening be done randomly. Thus children, the elderly and the infirm get caught up in the net, taking up the attention of screeners that could better be directed elsewhere.

Profiling is a way of better directing resources — and done politely, professionally and with common sense, it needn’t be punitive and demeaning. After 9/11, the London subway bombings and these latest arrests, the profilees can hardly be surprised.

But, as has been pointed out, one of those arrested in the British plot didn’t fit any profile — a young mother with an 8-month-old baby. She would have received the routine screening but nothing special.

The U.S. Transportation Security Administration is experimenting with behavior detection — screeners trained in reading body language, mannerisms and facial expressions — to spot someone under the stress that a would-be terrorist might be. And one would think that a mother about to blow herself and her baby out of the sky would exhibit at least some stress.

The problem with this approach is that it can be arbitrary. People in airports can be stressed out for lots of reasons, including being stuck in a slow-moving security line with the departure time approaching. Over time, though, behavioral detectives should develop the kind of expertise, that fifth sense, that good street cops do.

Until there is a perfect explosives detector, security experts will have to focus on the human side of making screening more efficient, less intrusive and, to be sure, more effective.

(Contact Dale McFeatters at McFeattersD(at)