Although that is the correct definition for 'passengers' i think you'll find that the definition for 'load factor' is some-what different, taking into account no-shows, giving an actual on-board (at the time of flight) stat. Although no-show rates are usually between 2 and 8% per flight - counting them in load factor analysis would certainly give a more optimistic view! But an airline's success must also be measured in being able to either reduce the no-show rate or over-come it by over-booking, else lost opportunity in ancillary revenue...