Thanks Klydon.

DC, I agree if you can identify high risk group on a well formed criterion(well is the keyword IMO), then you can criminally profile them.
Are you saying that being arab/muslim male of certain age is the only way to describe the terrorists? That is certainly not true. That is a ill-formed criterion. I am not sure if you are aware, but the Visa process for all middle-eastern countries routinely takes 6 months or so. The US embassy does a thorough background check and only then grants visa. This is not true for all countires. BTW I am talking about post 9/11 not when Atta came in. I was given Visa across the counter in 2005, but my Iranian friends have several months of waiting. This includes grandmas, parents, everyone, not just under-30 males. After doing all these checks, now imagine the humiliation of an innocent person if some passenger were to report to the airline staff that they feel suspicious because he has a turban or beard or some such ridiculous thing. And FYI, they don't allow anyone to come to US to study nuclear engineering, space, aircraft related degrees etc after 9/11. Whosoever enters US now with a valid Visa has already undergone huge amounts of checks (with exhaustive profiling -racial or otherwise). There is no need for common public to take up investigation based on thier prejudices. Or for that matter even airport authorities, unless they have some specific information about the person. If they want to play safe, then check everyone. That is really safe.