Section 50(1)(viii) in The Delhi Metro Airport Express Line, General Rules, 2010
(viii)the train operator of the assisting train, if in the rear, will drive the combined consist in Restricted Manual mode at a speed not exceeding ten kilometer per hour, while exchanging communication with the train operator of the defective train in the lead cab until the defective train is at the platform of the next station, all passengers shall be detrained from the defective train, and the combined consist shall then be moved further until the assisting train is completely on the platform, and all passengers of assisting train shall then be detrained at the station and the combined consist worked to the depot in Restricted Manual mode at a speed not exceeding ten kilometer per hour, with leading and intermediate train operators exchanging communication on cab to cab telephone particularly if being assisted from rear.