GM1 ATCO.C.040(b) Validity of synthetic training device instructor endorsement ED Decision 2015/010/R REVALIDATION (a) Successful completion of the refresher training in practical instructional skills and current operational practices may be verified by several means, for example by: (1) dedicated or continuous assessment; (2) peer assessment; or (3) demonstration of practical instructional skills. (b) Current operational practices may be refreshed by transitional and pre-on-the-job training....