Evidence for significant energetic electron precipitation by magnetospherically reflected (MR) whistlers has recently been found in SAMPEX energetic electron data <Blake et al., 2001>, implying that these waves undergo many reflections before being attenuated through Landau damping. We quantify the Landau damping of MR whistlers, using recent energetic electron data from the HYDRA instrument on POLAR and show that the MR wave components can endure for as long as ~20 seconds and undergo as many as 17 reflections before experiencing a 6 dB power loss due to Landau damping. Our results suggest that MR whistler wave energy may thus significantly enhance the total amount of energetic electron precipitation induced by each individual lightning discharge.