Aerospace Instrument-Making Annotation << Back H&#8734; Robust Control Synthesis Using Nonlinear Programming Leibov R.L., Gurevich O.S. This paper presents aircraft turbofan engine H∞ robust stability control synthesis using unconstrained nonlinear programming. The results of proposed technique application for two closed-loop SISO control systems with electronic digital controller and for closed-loop MIMO control system are presented. The observer and controller parameters for nonlinear programming solution initial approximation are calculated using the H2 control theory. Keywords: control system stability robustness, closed-loop SISO control system, closed-loop MIMO control system, electronic digital controller, observer and controller, H∞ control theory, H2 control theory, unconstrained nonlinear programming, aircraft turbofan engine. DOI: 10.25791/aviakosmos.12.2023.1378 Pp. 18-28.