In this paper, we present a detailed study of the physical dynamics of the program/erase (P/E) operations in nitride-based NAND-type charge trapping silicon-oxide-nitride-oxide-silicon (SONOS) flash memories. By calculating the internal oxide fields, tunneling currents, and trapping charges, we evaluated the simple charge trapping mechanism. We calculated transient P/E threshold voltage (VT) shift considering the ONO fields and tunneling currents. All the parameters were obtained using totally physics-based equations with no fitting parameters or optimization steps. The results show conventional NAND SONOS flash memory P/E characteristics in the Fowler-Nordheim (FN) operation regime. Also, these P/E simulation results agree with the measurement data of 30 × 70nm2 (L × W) SONOS flash memory devices that have 2.3/12/4.5 and 3/9/7nm ONO stack layers. This model fully accounts for the VT shift as a function of the applied gate voltage, transient time, and thicknesses of silicon oxide and silicon nitride layers, which can be used for optimizing the ONO thicknesses and the parameters for improving performance.