Red clump distance validation with the external catalogue L20. To enhance the illustration we use a larger RC sample here (147 deg < l < 219 deg and |b| < 30 deg). Panel a: comparison to L20 shows the presence of a population for which distances are overestimated using the K band. This isdue to very high photometric errors (i.e. (e_jmag| e_ kmag) > 0.025). (b) Comparison between G and K band derived distances also highlights the same trend: K band distances are overestimated for poor photometry stars. (c) Replacing K band estimates with G where (e_jmag| e_ kmag) > 0.025 improves agreement with L20.