We use 3D hydrodynamical numerical simulations and show that jittering bipolar jets that power core-collapse supernova (CCSN) explosions channel further accretion on to the newly born neutron star such that consecutive bipolar jets tend to be launched in the same plane as the first two bipolar jet episodes. In the jittering-jets model, the explosion of CCSNe is powered by jittering-jets launched by an intermittent accretion disc formed by accreted gas having a stochastic angular momentum. The first two bipolar jets episodes eject mass mainly from the plane defined by the two bipolar axes. Accretion then proceeds from the two opposite directions normal to that plane. Such a flow has an angular momentum in the direction of the same plane. If the gas forms an accretion disc, the jets will be launched in more or less the same plane as the one defined by the jets of the first two launching episodes. The outflow from the core of the star might have a higher mass flux in the plane define by the jets. In giant stellar progenitors, we do not expect this planar morphology to survive as the massive hydrogen envelope will tend to make the explosion more spherical. In SNe Types Ib and Ic, where there is no massive envelope, the planar morphology might have an imprint on the supernova remnant. We speculate that planar jittering-jets are behind the morphology of the Cassiopeia A supernova remnant.