The spot cost strategy for the One Gap algorithm, which compares
scheduling the current aircraft to take off between the last two
projected takeoffs, if it can fit, against scheduling it to
take off last.
This factory is used to have the DPSequencer carry out the One Gap
algorithm, which allows the aircraft currently being sequenced to
look back at the predicted takeoff times of the last two aircraft to
take off and determine if it can fit into the gap between them
without violating CPS, ready times, or adding delay to the second of
the two aircraft it is trying to fit between.