Crew scheduling

Crew scheduling is the process of assigning crews to operate transportation systems, such as rail lines or aircraft.

Complex

Most transportation systems use software to manage the crew scheduling process. Crew scheduling becomes more and more complex as you add variables to the problem. These variables can be as simple as 1 location, 1 skill requirement, 1 shift of work and 1 set roster of people. In the Transportation industries, such as Rail or mainly Air Travel, these variables become very complex. In Air Travel for instance, there are numerous rules or "constraints" that are introduced. These mainly deal with legalities relating to work shifts and time, and a crew members qualifications for working on a particular aircraft. Add numerous locations to the equation and Collective Bargaining and Federal labor laws and these become new considerations for the problem solving method. Fuel is also a major consideration as aircraft and other vehicles require a lot of costly fuel to operate. Finding the most efficient route and staffing it with properly qualified personnel is a critical financial consideration. The same applies to rail travel.

The problem is computationally difficult and there are competing mathematical methods of solving the problem. Although not easy to describe in one sentence, the goal is the essentially same for any method of attacking the problem:
Within a set of constraints and rules, move a set roster of people with certain qualifications, from place to place with the least amount of personnel and aircraft or vehicles in the least amount of time.
Lowest cost has traditionally been the major driver for any crew scheduling solution.

4 Parts

Although not a "rule", We can describe at least 4 parts of the equation that are ingested by the computational process:

• People and their qualifications and abilities.
• Aircraft or vehicles and their "People" qualification requirements and their cost to operate over distance.
• Locations and the time and distance between each location.
• Work rules for the personnel, including Shift hours and seniority.

In crew scheduling the rules and constraints are typically a combination of:

• government regulations concerning flight time, duty time and required rest, designed to promote aviation safety and limit crew fatigue,
• crew bid requests, vacations,
• labor agreements
• aircraft maintenance schedules
• crew member qualification and licensing
• other constraints related to training
• pairing experienced crew members with more junior crew members
• returning crew to their base at the end of their trip (called deadheading)

All of these issues need to be addressed in order to create a satisfactory solution for personnel and management of the organization. For the Crew member in a seniority based system schedules are decided largely on workplace seniority. Those at the top of a seniority list are allowed some choices. As assignments are made and the remaining roster of personnel becomes fewer, managements' systems start to assign the remaining trips based on a weighting of the 4 previously mentioned variables, without any input from personnel.
This does not allow the personnel to have any choice or voice in the schedules they receive. This lack of scheduling awareness until the end of each scheduling period is a major workforce issue and an employee morale problem, often creating a tenuous situation especially where a collective bargaining agreement is in place, and particularly at negotiation time. To address this issue, and to satisfy the growing voice of personnel to have a say in their schedules, in the 1970s the company SBS International, led by Mr. Christian Boegner, created the concept of a Preferential Bidding System (PBS). This was a new method of allowing personnel to create input data that factored in the calculations of the schedules, while still allowing management a level of control over critical business decisions. This has become a standard in the industry. The newest approach to PBS and crew scheduling takes advantage of the interaction possible via the web, which wasn't possible in the 1970s.^[1]

Real Time

Crew members and management can interact with schedules and data in a real-time web interface. Status can be seen and acted upon as it develops and changes, rather than requesting or bidding for a schedule once, then waiting to see the outcome. Although that advance itself was revolutionary at the time Mr. Boegner developed the mathematical algorithm to do so, interactive live PBS crew scheduling is the next step. The internet and its reach are starting to change crew scheduling within the large, global organizations that use it.^[2]

Disruptions

Additional unplanned disruptions in schedules due to weather and air traffic control delays can disrupt schedules, so crew scheduling software remains an area for ongoing research.^[3]

Related topics (systems)

• Preferential bidding system
• Fatigue (safety)
• Automated planning and scheduling

Related topics (algorithms and software)

• Linear programming
• Column generation
• Tabu search

• Fatigue Avoidance Scheduling Tool

References

1. ^ http://www.crewingsolutions.com/sites/all/files/resources/SP-WhitePaperPBS.pdf
2. ^ http://www.carmensystems.com/research_development/articles/crtr0303.pdf "Solving the World's Largest Crew Scheduling Problem"
3. ^ http://www.engr.pitt.edu/~schaefer/Papers/UncertainCrewSched.pdf "Airline crew Scheduling under Uncertainty"