I would like to comment on answer given to the above question.
I think kirpan upto 5 inches could be wear. My father recently went to US by Air India flight and used 5" kirpan and there was no problem.
Thanks
IPS Sethi
Normally, you will not get past security with a 5 inch kirpan. I have had my kirpan taken away. You can risk it, but you might 1: loose your kirpan 2: be considered a security threat and risk not being allowed on your flite. Air India may be lenient. U.S. airports and foreign airlines are not lenient.