Workforce scheduling
October-November 2021

About the company

Charter Aviation Services (CAS) is an aviation school that trains commercial pilots en Colombia. They deliver theoretical and practical courses in all aviation related areas. The have their own fleet of training planes and are based in Barrancabermeja airport where they attend students from all around Colombia.

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The Challenge


The goal is to help CAS optimize their class schedule. To program a class, three things are required: a student, an available instructor and an available plane. The objective is to fit the maximum number of classes in a limited period of time. So far CAS used to realize the schedules manually. Which is not only suboptimal but also very tedious because of the huge amount of constraints that have to be taken into account. For example, the maximum and minimum daily hours that instructors and students can work, planning the schedules in compliance with the regulations that requires specific maintenance programs for the planes, taking into account setup times when a plane or an instructor is changed between two classes, etc.



decrease in
overall distances


 makespan reduction


of overall cost reduction


faster execution time

Winners of the Challenge

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Tania Lorena Granados

Sandra Diaz

The software Tania and Sandra developed reduces by 24% the number of required auditors in just 4 seconds of running time. The approach is based on finding an equilibrium between reducing the working days and minimizing the overall distances. Their solution results in saving 16 working days and 10% of the overall distances. In addition to their software, Tania and Sandra analyzed Baobab approach and proposed two modifications which result in around 6% reduction in costs and 25% in the number of required auditors.

Their work has been submitted to an international operations research conference in Spain.

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Maria Alejandra Prieto

Daniela Catalina Jimenez

Maria Alejandra and Daniela's software manages to reduce the overall costs by 8%. Their approach is based on a first phase of clustering that prioritizes the opportunity cost of inter cities distances. The solution results in 15% less auditors, -10% overall distance and -6% makespan. All Baobab instances have been improved and the execution time is 500 times faster compared with Baobab's original approach.

Their work has been submitted to an international operations research conference in Spain.

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  • LinkedIn
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Andrea Amaya

Juliana Cardona

En just a few seconds of running time, Adrea and Juliana's software reduces the total cost by 6%. In more details, their solution reduces the number of required auditors by 45% and improves significantly (85%) the match with auditors preferences. They also discovered two key insights to reduce costs, identifying the relation between holidays, hired auditors and the number of cases where half workdays are required.

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Catalina Bohorquez

En less than 15 seconds, Catalinas's software reaches a solution with a cost 11% lower than Baobab's reference solution. The approach is predicated on the idea of efficiently creating groups of municipalities to optimize distances and use more effectively the auditors. This approach reduces overall distances by 32% and reduces the number of required auditors by 21%.

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—  Lina Caballero Galvan —

HR and management Director

Charter Aviation Services

The Challenge was a fulfilling experience where our company presented a real problem with our operational solution. The students obtained a better solution applying what they learned in their Optimization course. Their presentations were very professional and they presented improvements from different perspectives that helped us in our work in the company.

We would like to thank all the students who took part in the Challenge for the excellent results and professor Rabie for his leadership. He created a space in his course where both companies and students could work together on real problems and provide solutions based on what they learned in their class.

Thank you very much.

El Challenge Javeriana fue una experiencia gratificante y enriquecedora que permitió al Centro de Instrucción Aeronáutico presentar un problema real con una solución actual y obtener de esta una mejor solución realizada por los alumnos que al aplicar las teorías aprendidas en la asignatura Optimización, demostraron un gran profesionalismo durante la sustentación, donde mostraron una mejora al problema desde perspectivas diferentes que nos han servido para trabajar dentro de la compañía.

Queremos agradecer a todos los alumnos que participaron en el Challenge-CAS Javeriana 2021 por los excelentes resultados que obtuvieron en sus soluciones y al profesor Rabie por guiar y permitir este espacio de acercamiento y trabajo conjunto dentro de la asignatura, para con las empresas y los alumnos, quienes desde la academia comienzan a trabajar en problemas reales dando solución con lo que han aprendido durante la carrera y específicamente en la asignatura Optimización de Operaciones.

Muchas Gracias

A word from the professor

Scheduling is one of the most common problems in Operations Research. A set of task has to be processed (in our case the classes) in a machine which is the bottleneck of the process. The whole optimization consists in getting the most out of this bottleneck. There are plenty of techniques to handle this problem. In this challenge however, identifying the bottleneck was far from obvious. Is it the instructor? Is it the planes and which ones? The reality is that in our case the bottleneck was changing depending on the solutions. The students had to analyze where the limiting constraints were and they developed techniques to dynamically identify them to make the best use of the available resources. By doing, so not only did they develop effective software but they also discovered key insights that helped the company improve their processes.


Prof. Rabie Nait-Abdallah

Leader of the Challenge

Javeriana University