Directed sideward flow of light charged particles and intermediate mass fragments was measured in different symmetric reactions at bombarding energies from 90 to 800 A MeV. The flow parameter is found to increase with the charge of the detected fragment up to Z = 3–4 and then turns into saturation for heavier fragments. Guided by simple simulations of an anisotropic expanding thermal source, we show that the value at saturation can provide a good estimate of the flow angle, Θ flow, in the participant region. It is found that Θ flow depends strongly on the impact parameter. The excitation function of Θ folw reveals striking deviations from the ideal hydrodynamical scaling. The data exhibit a steep rise of Θ flow to a maximum at around 250 – 400 A MeV, followed by a moderate decrease as the bombarding energy increases further.