For the Operation of Commercial aircraft, airlines use manufacturer data that are common to all aircraft from the same type. However, during its lifecycle, performances (fuel consumption, speed, etc) for each individual aircrat will change as engines are ageing, aircraftt strucrure can me modified, etc. Through PERF-AI, we apply machine learning technologies to flight data to identify the change in performance for each individual aircraft and provide airlines with updated data that in turn will allow to operate more efficiently. Safety Line has been working since several years on the optimization during climb phase using Artificial Intelligence (OptiClimb). Thanks to PERF-AI, we will be able to provide extended services to the airline industry and possibly to manufacturers. At the end of the project we were able to create tail specific performance model for individual aircraft and use actual data to propose optimized flight path to be flown by the pilots for new flights. This approach can reduce fuel consumption and CO2 emissions by a few percents, which is very significant at the industry level.