The problem
corresponds to a model sequencing problem, where the processing
times (number of passengers gp) of different models
(planes p 2 P) are to be evenly spread over the production cycles
(landing slots t = 1, . . . ,T) to balance the workload at an assembly
line with a single station. In its structure, the problem is also similar
to the unconstrained maximum job cost sequencing problem
(e.g. see Monma, 1980), unlike the latter however, ALP1 is NP-hard
in the strong sense as is shown in the following section.