SAFE is an acronym for the System for Aircrew Fatigue Evaluation:a computer program that includes a suite of algorithms that allow a range of factors influencing alertness in aircrew to be evaluated. It has been validated for use by the airline industry from a huge data set that has been compiled over decades of studies with commercial aircrew.

The  model takes and input of many thousands of rosters and returns fatigue scores throughout the duty, taking into account trans-meridian travel, cumulative fatigue, crew composition, on board napping and other variables. Estimated sleep can be manually adjusted as part of the interactivity that is designed into the model in order to find optimum solutions for problematic rosters.

Features and Benefits

The benefits and features of using SAFE are:

• It is The Standard model that is validated specifically for the aviation industry and is used by many major airlines.
• It is used by UK Civil Aviation Authority to assess applications for flight derogation. Using the same tool for internal assessment before submitting the case for derogation makes complete sense.
• It is very easy to use: the model works with very few inputs, indeed as few as just duty start time, finish time; start airport, finish airport and number of sectors (legs) flown during the duty.
• It accommodates time zone travel, changes to circadian rhythm and cumulative fatigue.
• It predicts likely sleep patterns – these are displayed automatically.
• It allows rapid assessment of rosters to highlight problematic areas for further investigation.
• It supports ‘what if’ scenarios: can interact with the model to change crew composition, in flight rest and sleep periods to reflect individual behaviours.
• It has a simple and powerful display for the analysis results: problematic areas are easy to identify and optimise.

Download this paper on Automated Collection of Fatigue Ratings at Top of Descent by David Powell, Mick Spencer and Keith Petrie as an example of how SAFE may be used in airline operations