Simultaneous measurements of ion cyclotron waves (ICW's) were performed on GEOS spacecraft and in the vicinity of their magnetic footprints with the French Mobile station. The detailed comparison between the two sets of data shown that while ICW's having FFHe suffer a reflection where the frequency locally matches the local bi-ion hybrid frequency. We extend the calculations of Rauch and Roux and calculate, as a function of the He+ concentration, the tunneling of ICW's through the stopband induced by the presence of minor He+ ions. It is shown that the transmission coefficient strongly depends upon the wave frequency for a given He+ abundance ratio. The results obtained are shown to be supported by existing observations.