Optimized crew rosters for the perfect balance

Optimization ensures efficiency, cost control, transparency and crew happiness


Airline crew members believe they are flag bearers of their airline and rightfully so. For them, duty schedules come second only to family. Creating crew rosters for them is a difficult task. Planners must ensure that schedules are maintained around the clock, resources optimized, and the crew are happy and satisfied. It is a challenge to strike that balance.

Adding to the complexity are regulatory rules, qualification and training requirements, crew contracts and cost, with crew cost as second most expensive line item for an airline. And to top this, there are business metrics and SLAs to be adhered to.

Any application platform for this critical function must implement the entire operational plan meticulously. It must map duty cycles to qualifications and skills, consider variations in duty timings that stretch, to sometimes, eighteen hours in one go. Among many more points of note, it must also cater for cycles through time zones that disrupt sleep patterns and result in fatigue.

Evolution of the rostering engine

Schedulers have hated to hear the question, who has made this roster? Any answer would bring criticism or applause, but they’ve had to live with it. Historically, while making a roster, inputs were manually made and they lacked forward visibility, especially to information like crew availability with changing flight schedules, which needed quick (re) assessment. Despite dedicated teams on the job, their output was often compromised for quality, making scheduling a tightrope walk.

Until the 1980s, much of crew scheduling was accomplished manually, with schedulers working mainly on two blank documents: one, a calendar chart with crew names in order of seniority, and the other, a list of flight departure or trips in the sequence of departure time. Crew was assigned to flights or trips in rotation. Data was maintained on tables: for flight time, number of international flights, trips and training & qualification registers. Rosters were created and each crew was painstakingly notified, individually.

Beginning of computerization

Computers started replacing manual systems in the 90s, with spreadsheets from software like FoxPro and Access. Pilot rosters started being published convincingly, using software. But many of these projects faced opposition from labor unions. Computerization of processes in cabin crew operations followed. Like, scheduling, flight planning, NOTAM management, FDTL monitoring and particularly, TQD (Training Qualification and Documentation). However, fully computer-generated crew schedules and rosters was still a distant dream.

It was only in the 2000s, with the arrival of the new generation of flying and ground crew, who were ready to accept change, is when the attitude towards computerization changed. But it took some time for software applications to gain their acceptance as tools in crew management. The primary reason manual systems lingered in airlines, compared with the technology adoption in other industries, was the human unwillingness to give up to the machine. There was also a general mistrust for and apathy towards change. Fear of losing jobs was another factor, not to forget the lack of a good scheduling system that came off the shelf, and the absence of qualified resources who would champion the new system.

Computers in crew scheduling

By the late 2000s, operational departments in airlines, like network planning, engineering and flight dispatch, were using computers. Regulators began mandating the use of computers in scheduling as well. Among large carriers, this was necessitated by the increased complexities of network operations, that came with growth in crew numbers and crew bases, by fleet type or size. Adherence to complex flight and duty time calculations, the regulatory mandate to monitor flight time limitations (FTL) and qualifications of individual crew, required applications software. Also, crew management had to be made transparent, not to forget the need to reduce the effort in scheduling and notifying every crew member and stake holder in flight operations, up to the last service provider.

ARMS® on the scene

In 2012, Laminaar introduced ARMS® or the Aviation Resource Management System for crew scheduling. It had four modules:

  • A Crew Trip Optimizer to create optimized and anonymous crew trips or pairings
  • An Auto Roster for crew rostering
  • Training, Qualification & Documentation or TQD for monitoring, planning, storing crew information
  • A Crew Tracking module

The application was widely accepted by many airlines in S Asia and elsewhere and none other than India’s national carrier, Air India, was a direct beneficiary and a marquee client.

Rostering Optimizer

Over the years, with increased user proficiency among ARMS® users and the enormous amount of crew data that was available, roster planning was ready for optimization with mathematical solvers.

Laminaar had envisioned this. A Crew Rostering Optimizer was brought to the drawing board. Months of dedicated effort in iterative design, development and testing followed. The product was delivered to none other than Air India, by the summer of 2021.

ARMS® Crew Rostering Optimizer – CRO

The ARMS® CRO addresses roster planning as a large-scale mathematical problem based on the science of Operations Research. It accommodates every variable, constraint and parameter that is needed to arrive at an optimized crew roster within minutes. It ensures fair and equitable distribution of work with no manual intervention. By simplifying the task of rostering, the CRO reduces effort, saves time and cost. Additionally,

  • The algorithms consider all roster attributes, parameters, priorities and business constraints.
  • The optimiser accommodates every duty task and assigns the best combination of those to the crew.
  • The optimiser keeps improving its output with repeated iterative runs.

CRO – Unique Features

Unique features of the CRO are:

Can be used for all kinds of operations – regional, long range and ultra-long range. CRO uses filters like aircraft type or fleet, crew bases and crew roles – e.g., Left Hand Side or Right-hand side for pilots, or Cabin In-charge, or Cabin crew. It can also use filters for various combinations of fleets, rule sets, statutory or planning (business) rules for roster making.

Makes rosters for specially qualified crew – for example, flights to critical or restricted airfields and areas, low visibility operations, or specific airline requirements to roster only international flights, domestic flights etc.

Can assign multiple types of cumulative rest periods – option made available for the scheduler, e.g., Assign Periodic Off in Master Definition or Rolling Bar functionalities.

Can optimize roster parameters – users can decide which roster parameters must be given extra leverage over others for optimized task distribution. E.g., Flight time, Landings, Previous Flight Time, Diurnals, Ac Types Flown, Non-Availability Due To Other Duties, Roster Period Flying Hours, Trip Distribution, Recently Flown Trips, International Operations

Buffers & gaps for roster stability – To ensure stability of published roster in post published period of actual day of operations, scheduling personnel can opt for various buffers, like,

  • Gaps between Back to Back Layover
  • Buffer between rest end and travel start of the next duty
  • Buffers between two consecutive night flight duties
  • Continuous work period between two weekly rests
  • Gap between weekly rest end and next travel start

Additional benefits to schedulers

  • Avoid rest buffer and night buffer for within trips – on occasions within a trip an airline may require to keep rest period buffers different from CRO. This feature enables a difference of buffer periods in trip and roster
  • Two separate duties allowed in a day – airlines may decide to assign or not assign more than one flight duty in a day, based on their business processes
  • Priority assignment as per crew endorsement – a crew may be endorsed for multiple aircraft, this feature enables crew to be scheduled for a fleet type of higher priority
  • Define weightage points – in master settings there is a provision for users to define default settings for roster attributes; previous settings can be saved too
  • De-Roster – a roster can be re-run or published after deleting the previous run
  • Cancel option – allows for stopping a running CRO process
  • View Progress & Status of Run – as per filters opted and optimize run time to a shorter duration. The CRO Status window provides; user can also set auto refresh in minutes as necessary
  • Key Productive Indicators (KPIs) – Infographics of Key Productive Indicators (KPIs) for parameters can be generated for user to assess results during a roster run

Synergy with other ARMS® systems

2700 crew scheduling test runs were performed while testing the CRO engine for different types of aircraft and network patterns, involving regional, long range and ultra-long-range flights. Also tested successfully was its ability to collaborate seamlessly with other application software modules of ARMS® like the network planning tool: FOSS, crew pairing tool: CTO, crew bidding module and crew portal of its crew management application: CMSS, and the ARMS® module for fatigue risk management: FRMS.


The ARMS® CRO directly impacts crew experience with a balanced roster plan with better distribution of work. It positively improves crew quality of life & crew satisfaction.

To planners, the ARMS® CRO makes the task of scheduling easy, without missing any parameter or business scenario. It provides analytical reports to measure the outcome of the CRO Runs. Most importantly, the CRO saves time and effort, offering planners the reward of a better quality of life.

To airline management, the CRO is a one stop solution that addresses crew quality of life with directly impacts the stability of crew in the airline, reducing attrition and saves crew cost.  It also affords them the time for and the visibility to focus on strategy, revenue and customer experience.

Client Testimonial

“Air India has been utilizing the new ARMS tool, Crew Roster Optimizer (CRO) for the past three months for Flight and Cabin Crew duty roster generation on Boeing and Airbus fleets.

As compared to previous legacy system, CRO provides optimized solution over  various crew roster parameters, e.g. “Flight Time”, “Lay Overs”, “International Flights”, “Diurnal distribution” etc.  The system provides maximum assignment of flight duty tasks with equitable work distribution amongst crew, as per Airline policies. CRO has enabled reduction of multiple roster runs, manual interventions  by end users, simplification of work and reduction of scheduling team man-hours.
The additional feature of visual and graphical representation of Key Productive Indicators (KPIs) for crew roster parameters enables crew schedulers to quickly assess the results. 

We appreciate the continued support of the ARMS team to Air India…”

Office of the GM CMS, Air India, 03 Nov 2021


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