the air shut-down. plus -- >> terrorism is terrorism no matter where it comes from. >> 15 years after timothy mcveigh's bomb, oklahoma city and the nation remember the victims and their families this morning. >> what worries me the most today is the lone wolf mentality. someone who's going to have, quote/unquote, the guts or courage to step over the line. >> tracking hate online with point and click ease. extremists thrive online. those stories and your comments right here, right now in the cnn newsroom. it is now day five of the no-fly zones across much of europe. volcanic ash from iceland is not as dense today. but about 20,000 more flights are cancelled. can you imagine that?