Turn calculator

A tool to visualise and comprehend the impact of aircraft turn performance in the en route phase of flight.

Access conditions

The turn calculator helps ATM specialists, including airspace planners, to visualise and comprehend the impact of aircraft turn performance primarily in the en route phase of flight.


The turn calculator was developed by EUROCONTROL to allow the user to input appropriate aircraft, route and weather data and then to predict the turn performance (colour-coded in blue). The tool then computes the geometry of both the 'Fixed Radius Transition' (FRT) and 'Fly By' for the given turn angle and displays the expected earliest ‘Fly By’ turn as well as the FRT.

The tool also gives information on aircraft performance through the turn, including the evolution of the bank angle, calculated groundspeed and load factor.


The turn calculator is not intended to be used as a route design tool although it may be useful during the planning (pre-design) and validation (post-design) phases.

The turn calculator is provided on the clear understanding that EUROCONTROL makes no warranty, whether express or implied, arising by law or otherwise, assumes no responsibility to any person or persons, and disclaims any liability with respect to the use of the software and any derivative works including, but not limited to, any express or implied warranty of fitness for a particular purpose.

Access conditions

To request the turn calculator, if you are experiencing issues with accessing or using the tool or to provide feedback, please contact us by using our page's contact form.