This may help some of the recent posters asking about travel around Europe hoping to avoid the Visa requirements etc.
Don`t know if its been discussed before, but it seems all persons who have left/travelled from/too the USA and then use European airlines are being logged and monitored by the US authorities.
http://www.statewatch.org/news/2003/oct/12pnrspain.htm
Like they say “Big Brothers a Watching”.
This may only apply to Europeans travelling to the US, but since the US are being given data by the Spanish, one could assume that the Spanish have access to US citizens entering into Spain illegally.