Thermal asperity (TA) sensor is used to investigate head disk interface (HDI) dynamics during operational shock. It is revealed that the output of TA sensor as a function of shock acceleration and back-off level. Air bearing modes being excited during operational shock indicates head-disk contact happens. The mechanisms and exciting sources of head-disk contact were explored by analyzing the TA sensor signal. Both experiment and simulation results show that motor base mode and head stack assembly (HSA) bending mode are the two most important contributions to head-disk contact. From this study, TA sensor is found to be useful for in situ monitoring of operational shock dynamics and, thus providing the strategies to improve shock-resistant performance.