Hydrodynamic journal bearings supporting high mass rotating machinery are subjected tolow rotational speeds during start-up or idling phases. These working conditions need ahydrostatic pressure contribution to ensure a correct load capacity when the hydrodynamicpressure is not established yet. This is possible by means of hydrostatic lift pockets.These pockets avoid mechanical damages via sufficient film thickness from start-up tohydrodynamic working conditions. In a first part, it is showed how an existing isothermal3D hydrodynamic numerical modelling of tilting pad bearing has been adapted to take intoaccount the lift pocket impact on static bearing performance. This approach is only validfor low rotational speeds, when inertia step pressure effects (rises or drops) at thefilm-pocket edge can be neglected compared to the total bearing pressure pattern. Then,numerical simulations have been performed, from 1 to 200 rpm with pockets and from 75 to200 rpm without pockets. The results have been compared and discussed in terms of pressurefields and bearing static performance such minimum film thickness, friction torque orrotor center position. Therefore, the interest of such lift pockets has been highlighted.Finally, calculations with and without pockets have been carried out in case of a strongbearing misalignment. As a result, the benefits of the lift pockets in this configurationare also significant in terms of static performance.