The projected levels of NOх emissions for the standard LTO cycle were shown. The estimated range of applying the advanced schemes of fuel combustion in terms of engine OPR was reviewed based on of research results in world experience. Based on the Ivchenko-Progress SE experience in design of combustion chambers the forecasting of the NOх level emitted from air engines was made. The estimated rates of NOx emission level reduction were determined and shown for the period till 2050 engines depending on engine thrust class. The probability of achieving the aims of Flightpath 2050, Challenge 3, Goal 1, was shown for engines with different thrust range.