The UPWing project investigates wing technologies to be used on a next generation short and medium range transport aircraft. One promising technique to further reduce structural weight is active load alleviation. To mature these load control functions, a wind tunnel experiment is conducted in transonic conditions within UPWing WP2.3. Based on a reference configuration, a wing wind tunnel model is developed, featuring sweep and high aspect ratio. In the experiment, a gust generator introduces disturbances in the airflow, which then interact with the flexible wing, exciting its dynamics. The motion is sensed by distributed acceleration sensors, load estimators, and a (virtual) LIDAR. These measurements are provided as feedback / feedforward signals to the control algorithms to be designed. Three trailing edge control surfaces are actuated to reduce the loads resulting from the gust encounter. These two presentations (Pt. 1 and Pt. 2) aim to give an overview on the activities underway to design gust load alleviation controllers to be tested in the wind tunnel. Pt. 1 will focus on the numerical model used for model-based controller design, while Pt. 2 will be concerned with the controller design itself. Challenges due to transonic flow conditions will be discussed and first results will be shown. The first step in model-based controller design is to generate a numerical model to mathematically describe the wind tunnel experiment. Two types of models are created: • a nonlinear simulation model for controller validation, • a linear state-space model for controller synthesis. The model includes a structural model derived from a finite element formulation, being condensed to a set of structural grid point. The aerodynamic model is based on the doublet lattice method. The aero-structural coupling employs a radial basis function approach. Control surfaces are modelled as a second order element, while the sensors are modelled purely geometrically, neglecting the very fast sensor dynamics. The challenge in controller design for transonic flow conditions is to accurately capture the nonlinear aerodynamic effects. The aerodynamic model is typically based on fast aerodynamic methods, such as the Doublet Lattice Method (DLM) based on linear potential theory are used to obtain frequency domain data for given reduced frequencies. For transonic conditions this is not sufficient, hence the DLM matrices will be corrected with data obtained from unsteady higher fidelity CFD