Computers are wonderful devices. Airlines use a procedure-program- called "yield management". The objective is to sell seats to derive the maximum profit per average seat yield. So early on weeks before a flight date, seats are offered at a certain price, as demand increases or decreases, the price is adjusted. Typically as the date approaches, demand increases as there are passengers needing to travel on short notice so the price increases. Ideally, every seat will be filled at the optimum price. But this is not a perfect bit of science so a few seats will be empty. On average however, the maximum yield per seat on average will be achieved. It works! That is why the person setting next to you may have paid much less than you or much more than you. For those that think that the airline should pass on their saving as per decreased oil prices and resulting increased profit in the form of a reduced fare, perhaps the airline might do this if you agreed to fly your usual flights as fuel prices increase while paying an increased fare to ensure that the airline made the same profit as before. I doubt that you would agree to that.