Upvote:2
Airlines have two reasions why they want to know their customer:
Among other things, APIS demands the full name, so it would be pointless to use anything less for internal purposes.
Upvote:9
What would you do if your passport were lost or stolen between the time you made the booking and the flight, of if you had to replace it for another reason?
Passport/Travel document number is a single unique key for every person.
That is not correct. The number is supposed to identify the document uniquely, so each person may have several passport numbers over the course of his or her lifetime.