In my experience (no specific stats) I belive the figures pax booked but no show probably runs at about 10% on long haul & anything up to 15-20 % on short haul trunk routes. OLCI pax would have to be included in the above figures but for pax that have checked in at the airport the no-show rates at the gate are not partucularly high we usually manage to round up most people eventually. You also have to weigh up the hassle of off loading pax as opposed to taking a delay whilst you track them down. On larger aircraft where the bags are loaded in ULD's as opposed to being bulk loaded it can take up to 20 mins to off load bags if you have to remove up to 6 bins to get to the one containing the pax bags. On short haul a/c where the bags are bulk loaded no show bags can be off loaded much more quickly and consequently no-show pax are more likely to be left behind whereas on long haul flts it can be a consedable undertaking to offl load no shows. Maybe there is someone out there who works in revenue management who might be able to provide some formal stats as most airlines spend a lot of time & money managing pax loads to avoid flying with empty seats.