At least a couple of sites recently had an article (here and here) about an airline pilot turning around close to the flight’s destination because he was not qualified to land. As usual with respect to aviation, the sites used a sensational title to the articles and only reported the part of the story that generated the most traffic.
Airline pilots are trained on new aircraft through an extensive program of classroom and simulator-based instruction. This is followed by Initial Operating Experience (IOE) in the actual aircraft on revenue-generating flights while under the watchful eye of an IOE instructor. At the end of the IOE period, the pilot is administered a line check which evaluates his/her performance. If it is satisfactory, the pilot is released to the line to begin flying trips on his/her own. If the pilot has just been trained in the Captain position there are restrictions placed on the pilot’s operations until a specified number of hours have been flown in the new aircraft, in the U.S. this is mandated by CFR 14, Section 121.652.