This paper describes the status of an on-going research work and investigates the problem of entry guidance of the Atmospheric Re-entry Demonstrator (ARD). We propose an entry guidance scheme that uses the flatness property. First, it is shown that the longitudinal dynamics of the ARD is flat and by using flatness property a feasible desired output and the associated nominal control input trajectory are easily generated. Next, a methodology to construct a nonlinear error model, which describes the dynamics of the trajectory tracking error, is derived using coordinate transformations of the flat outputs. A first order linearization of the nonlinear error model is performed along the nominal trajectory in order to formulate the nonlinear ARD longitudinal dynamics as Linear Parameter Varying (LPV) model. LPV control design techniques can then be used to construct the global control law guaranteeing stability and performance.