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SAFE model

Developed for and by the aviation industry

SAFE is our world class validated and mature biomathematical fatigue model that predicts fatigue hazards experienced by commercial aircraft pilots.

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SAFE (Systems for Aircrew Fatigue Evaluation) is a mature fatigue model to assess pilot fatigue originally developed for the UK Civil Aviation Authority and used by them since 1994.

SAFE has been adapted for use by airlines and is used across the world. Our clients include small and large commercial airlines, business and ATXO operators and regulators.

SAFE's powerful, feature rich tool used to create and assess both fatigue and operational risks in pilot schedules. It has been successfully used for investigating incidents and accidents and for aircrew and student education.

SAFE has been validated with comprehensive studies conducted since the 1980s for the UK Ministry of Defence and UK Civil Aviation Authority. After its original development, further studies have validated the model’s maturity and extended its usefulness in simulating novel operations such as ultra-long-haul duties and double-crew duties during the COVID-19 pandemic.

Airlines contributing to the original dataset include Air New Zealand, Emirates, Singapore Airlines, Britannia, Lufthansa, JAL, Pan Am, DHL, and British Airways who helped to study short, medium, long and ultra-long haul duties, and cargo operations too.

The first ULR operations in 2001 were made possible by extrapolating the SAFE model and evaluating possible windows of departure. Measurement made during the first flights validated the accuracy of the model and that the operations were safe.

SAFE was used to predict fatigue risks in the preparation of the European regulations for pilots of commercial airlines and business jets and in studies supporting Air Taxis, Emergency Medical Services, Helicopter Search and Rescue operations.

During the COVID-19 pandemic, SAFE was used to predict likely fatigue in extended back-to-back operations, where aircrew were not permitted to disembark at the destination. Duties of up to 36 hours were analysed by extrapolation and confirmed by local CAA analysis.


SAFE has a comprehensive set of features including:

SAFE can be used to identify operational fatigue hazards, compare schedules, assess fatigue reports, consider productivity and test regulations, with rosters being exportable to our powerful HARVEST analytics module.

SAFE can be used to evaluate the benefit of different fatigue mitigations and consider risk appetite.

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Be SAFE in our knowledge...

aviation specific

Developed specifically for Aviation

Developed specifically for the aviation industry and used by many airlines and regulators world-wide.

easy to use

Easy to use

Requires few inputs, integrating with crew management systems and supports sectors flown, in-duty rest, split shifts and other workload variables.

fast and flexible

Fast & flexible

Cloud based platform with fast algorithm library available for optimisation or for driving third-party fatigue management modules.



Supports ‘what if’ scenarios. Variables and factors can be altered to prospectively and retrospectively model the effects on fatigue and risk. 

Clear, direct problem solving

 Hazards are easy to identify and possible solutions can be evaluated in support of incident and accident investigation.

Cost effective

Fast to deploy and integrate into existing systems, and an inexpensive way of identifying hazards in large datasets.

Standalone or API interface
SAFE can be connected to scheduling or other software systems through a choice of APIs for automated roster uploading. It can also be used as standalone platform with rosters uploaded using the SAFE data template, or even by manual data entry.
Assess Planned or Actual Rosters
Pre-published schedules can be assessed and updated at any time after publication. SAFE can predict the fatigue in any schedule at any time. SAFE has fast algorithms and is used in real time by air taxis
Evaluation of new routes and schedules
SAFE can be used to assess the likely fatigue associated with new operations.
Incident Investigation
Post incident analysis can include a schedule analysis to identify the likely fatigue at the point of the incident and understand it as a contributing factor.
Real-time roster analysis
A fast version of the algorithm library is available for optimisation or for use of operations where frequent schedule changes arre prevalent.
On-board sleep modelling
SAFE supports modification of crew composition, sleep order and the location of on-board sleep to take into account the quality of rest.
Workload adaptation
Variations in workload due to factors such as weather conditions and approach complexity affect fatigue. SAFE enables variable aircrew workload to be included in the fatigue risk prediction.
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Using SAFE

SAFE is mature, flexible, easy to use and cost effective. It supports future, real-time and retrospective analysis of aircrew rosters, with the ability to make in-roster adjustments to explore options to reduce fatigue risks.

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SAFE calculates predictions of fatigue, alertness, operational risk optimised napping schedules and sleep/wake schedules. Data can be input manually, bulk uploaded or through an API from your rostering and crew solutions software.

SAFE is cloud-based and integrates directly with rostering software. It has capacity to upload tens of thousands of pilot schedules, calculating fatigue scores every 15 minutes throughout each duty period. It identifies fatigue hazards and provides tools to model mitigation strategies. 

Download a paper on Automated Collection of Fatigue Ratings at Top of Descent by experts at FRMSc and Air New Zealand as an example of how SAFE and CARE may be used in airline operations.

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