Appeal to accomplishment is a genetic fallacy wherein Person A challenges a thesis put forward by Person B because Person B has not accomplished similar feats or accomplished as many feats as Person C or Person A.
The reverse, appealing to the fact that no one has the proper experience in question and thus cannot prove something is impossible, is a version of an argument from silence.
Appeals to accomplishment are fallacies only when they are simple appeals to authority. It is not fallacious to rely on the testimony of a person who has attained a certain level of education or experience if they can produce further evidence to back up their positions when required.
Examples
References
Appeal to accomplishment Wikipedia(Text) CC BY-SA