On 31 March 1931, "Lexington", which had been near Guantanamo Bay Naval Base, Cuba, was ordered to aid survivors of an earthquake that devastated Managua, Nicaragua. By the following day, the ship was close enough to launch aircraft carrying supplies and medical personnel to Managua. During Grand Joint Exercise No. 4, "Lexington" and "Saratoga" were able to launch a massive airstrike against Pearl Harbor on Sunday, 7 February 1932 without being detected. The two carriers were separated for Fleet Problem XIII which followed shortly afterward. "Lexington" was assigned to Black Fleet, defending Hawaii and the West Coast against Blue Fleet and "Saratoga". On 15 March, "Lexington" caught "Saratoga" with all of her planes still on deck and was ruled to have knocked out her flight deck and have badly damaged the carrier, which was subsequently ruled sunk during a night attack by Black Fleet destroyers shortly afterward. "Lexington"s aircraft were judged to have badly damaged two of Blue Fleet's battleships.