what is one step down planning
Hello guys, today I heard, that you have to plan an alternate in case of destination wx is below minimum at the eta with the one step down or one step below or one step under method. It shall mean, if there is at the alternate an precision apch (ils) and an e.g. vor apch you have to assure that the wx at eta (altn) is sufficient for an apch that is (with respect to precision) one step under the "best precision apch". is that correct? where can you read more about it? is it a law??
yours lusthansa!