Under Secretary of notification under such subsection. (2) Significant variances in costs or schedule If a likely cost overrun is greater than 20 percent or a likely delay is greater than 12 months from the costs and schedule specified in the acquisition program baseline for a major acquisition program, the Under Secretary for Management shall include in the notification required in paragraph (1) a written certification, with supporting explanation, that— (A) such program is essential to the accomplishment of the Department’s mission