Passport details
On some airlines, flying on routes to certain countries within the EU, there is a requirement to provide passport details prior to being able to check in online. An example is flights from the UK to Spain. I don't with to go into the merits of the system (i.e. Gordon Brown is turning us into a police state versus the argument that it's a necessary method to defeat terrorism) - but instead stick with the day-to-day technicalities of the operation of the system.
If I were to provide details of a fake passport when checking in online, but using my genuine EU passport when actually travelling and to present to the immigration official in person, what would actually happen ? I've experimented in the past more than once by declaring an incorrect date of birth for online checkin and never had any problems at the airport !
Does the online checkin process gain any sort of verification from national Govt prior to issuing the boarding card for printout ? Is any comparison performed between the passport details provided by the airline to the Govt of the country where the flight arrives, and the passport presented by the passenger ? Do staff at the gate even care beyond ensuring that the name on the boarding card matches the name in the passport ?