The No.3 U.S. weapons maker also raised its 2016 earnings forecast to $10.40-$10.70 per share from $9.90-$10.20.
Northrop's results come a day after larger rival Lockheed Martin Corp
also raised its 2016 forecast and reported better-than-expected quarterly sales, benefiting from its acquisition of helicopter maker Sikorsky Aircraft.Revenue at Northrop's aerospace systems, which makes manned aircraft, drones and space craft, increased 3 percent in the first quarter ended March 31. The business accounted for about 43 percent of total revenue.Total sales were nearly flat at $5.96 billion, but beat analysts average estimate of $5.93 billion, according to Thomson Reuters I/B/E/S.The company's net income rose nearly 15 percent to $556 million, or $3.03 per share. Excluding items, it earned $2.59 per share, comfortably beating analysts estimates of $2.49.Federal and foreign income tax expense fell 45.5 percent to $120 million.Up to Tuesday's close, Northrop's stock had risen 7.8 percent in value this year. (Reporting by Sweta Singh in Bengaluru; Editing by Savio D'Souza)