Overbooking
Having worked in airline revenue management let me throw in my two penny worth. Overbooking is a necessary evil. Passengers do noshow. It is a fact. I recall it was not uncommon on some services for more than 25% of passengers to noshow which could mean 100+ empty seats. By overbooking, you can actually improve customer service by allowing somebody to travel at the time they want to travel and not on the next flight that appears to have availability. For sure you do not want to deny boarding to anybody, hence judious use of noshow data to predict by flight by day of week, by time of year to predict the likely noshow factor and then you would subtract a margin. It was amazing how easy it was to predict noshows using the data sensibly. Paris on a Friday evening was often overbooked by 30% and still cleared. Nice at the same time might be 10% overbooked. Not only did we cut the denied boarding rate by using the data for the first time by increasing some overbooking profiles but reducing others, the extra revenue from overbooking actually equated to the airline's profit at the time. However, having said this if you are an airline operating on monopoly domestic routes with lots of leisure traffic then you might decide not to overbook. It was also at the time when booking a return was cheaper than a single - remember those days? Never forget, overbooking is in the customer interest as many, many more passengers can be carried than are denied boarding and it helps keep fares down as the cost of an empty seat is huge. We missed a trick all those years ago as we could have promoted it as the airline's first green policy!