Aero-engines operating in sand (CMAS) laden environments often encounter severe problems with thermal barrier coatings (TBCs) due to CMAS infiltration and erosion damage. A common strategy against CMAS infiltration are sacrificial oxide layers, which are applied upon TBCs. Since both damage mechanisms occur parallelly in a turbine, this study focuses on the erosion mechanisms concerning CMAS-infiltrated TBCs and its sacrificial layers. EB-PVD Yttria partially stabilized zirconia coatings protected by suspension plasma sprayed (SPS) Al2O3 layers have been tested. The CMAS infiltration was realized by an isothermal heat treatment. Erosion tests were carried out at room temperature in an in-house erosion test rig. Confocal microscopy was used for evaluation, which made it possible to discuss the eroded volumes over the time. Microstructural examinations as well as crack identification were carried out using SEM, EDS and Nanoindentation. Our microstructural examination verified that the infiltration depth of CMAS, the formation of a reaction layer in the sacrificial layers as well as the adhesion behavior of SPS on TBC are influencing the erosion behavior. Especially for SPS layers the erosion mechanisms varies between SPS-spallation caused by compaction damage, vertical cracks at thin reaction layers and a gradual erosion removal at full infiltrated SPS layers.