PBS Core Algorithms
This algorithm uses a "First Come First Serve" concept. For each crewmember in a group of the same bid package, starting with the most senior, it awards the best legal line based on his/her preferences without a conflict with his/her carry-in and pre-defined activities, then removes the awarded pairings from those available. In the same way it awards the best legal line for the next crewmember. This process is repeated until the most junior crewmember has been allocated a line.
The best line is defined by one with the most prioritized preferences or the most points (if it is a weighted/pointed system) of the preferred pairings and line characteristics. (In the case of more than one equal important best lines available, an arbitrary one will be awarded.)
Greedy Algorithm does not consider the preferences of junior crewmembers, it offers lowest overall satisfaction.
Using this algorithm alone will not control open time. Uncovered pairings will be left on any date throughout the bid month, especially during holiday periods as a result of most crewmembers preferring off on those days. Therefore, it requires more reserve crewmembers to cover these uncovered pairings.
In brief, the greedy algorithm cannot achieve high overall satisfaction and cannot control open time. It cannot create the line holders required. Unfortunately, it is the fundamental algorithm being used by almost every PBS on the market today.