The NASA JPL AirSAR with P, L and C band radars flew over a hemlock forest in the summer of 1989. A ground crew of NASA personnel and George Washington (GW) participants made extensive canopy and ground truth measurements in the week before the flights. Tree trunks, branches and needles were measured as well as soil roughness profiles over a site that was 200m by 200m. The SAR backscattering coefficients were computed using Distorted Born Approximation (DBA). The surprising results showed that only the C band cross sections agreed with the SAR data. The P and L band theoretical results were 8 to 9 dBs too low. The results of the ground truth data collection and theory are given in Chauhan, et.al., IEEE Trans on Geosci. Remote Sens., Vol 29, pp 627-638,1991.