Airline spill analysis – beyond the normal demand

Most research on airline passenger spill has assumed a normal distribution for the nominal demand. But empirical evidences show that normal distribution is not suitable in many cases, especially for spill analysis of business and first class compartments. In this paper, we derive formulae for calculating the expected number of spilled passengers when the nominal demand is assumed to follow a normal, a logistic, a log-normal, or a gamma distribution. The spills under these alternative distributional assumptions are compared numerically. Finally, the paper demonstrates that, for each of the four distributions, one can construct a generic observed load factor (OLF) table, which does not depend on aircraft seating capacity.