This technical note uses regression analysis to examine the conditions of rigid airport pavements and subgrade soils based on Heavy Weight Deflectometer (HWD) results, where back-calculation analysis is applied to estimate the relevant modulus under dynamic HWD loads. The results from regression analysis of accurately measured HWD deflection can be a benchmark for maintenance and rehabilitation (M&R) of airport pavements. Based on the HWD deflection data collected in an indoor experimental environment, a linear relationship between measured deflections and the HWD drop loads (DL) can be examined through a regression analysis with R2 > 0.99. The back-calculated moduli can maintain a reasonable fluctuation range under all HWD drops and varied material properties. A linear elastic responses of rigid airport pavement under different DLs was observed in this statistical analysis. The low HWD DLs (50 kN and 100 kN) provided an overestimation for subgrade moduli. Meanwhile, a more stable estimation of subgrade moduli was provided by 150 kN DL under varied material properties. Therefore, in order to accurately measure the responses of subgrade, a higher HWD load, such as 150 kN, is suggested.