Thresher Base
United States Submarine Veterans
The Tragedy
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USS Thresher Underway
On April 9, 1963, USS Thresher departed the Portsmouth Naval Shipyard with 112 crew members and 17 technical observers for deep diving exercises in an area approximately 200 miles East of Cape Cod, Massachusetts .
USS Skylark, (ASR-20)
Submarine Rescue Ship That Accompanied USS Thresher On April 9 & 10, 1963
USS Skylark provided surface support and communications for the deep diving sea trials.
USS Skylark Ships Log, 10 April 1963, Part 1 of 3
USS Skylark communicated with USS Thresher via an underwater telephone during the deep diving sea trials.
0747: USS Thresher begins its descent the test depth.
0752: USS Thresher levels off at 400 ft (120 m), contacts the surface, and the crew inspects the ship for leaks. None are found.
0809: Commander Harvey reports reaching half the test depth to USS Skylark
0825: USS Thresher reaches test depth.
0902: USS Thresher announces to USS Skylark she is turning to "Corpen [course] 090." At this point, transmission quality from Thresher begins to noticeably degrade.
0912: Skylark pages Thresher on the underwater telephone: "Gertrude check, K [over]." With no immediate response (although Skylark is still unaware of the conditions aboard Thresher), the signal "K" is repeated twice.
USS Skylark Ships Log, 10 April 1963, Part 2 of 3
USS Skylark communicated with USS Thresher via an underwater telephone during the deep diving sea trials.
0913: Harvey reports status via underwater telephone. The transmission is garbled, though some words are recognizable: "[We are] experiencing minor difficulty, have positive up-angle, attempting to blow." Officers on Skylark could hear the hiss of compressed air.
0914: Skylark acknowledges with a brisk, "Roger, out," awaiting further updates from the SSN. A follow-up message, "No contacts in area," is sent to reassure Thresher she can surface quickly, without fear of collision, if required.
0915: Skylark queries Thresher about her intentions: "My course 270 degrees. Interrogative range and bearing from you." There is no response, and Skylark's captain, Lieutenant Commander Hecker, sends his own gertrude message to the submarine, "Are you in control?"
0916: Skylark picks up a garbled transmission from Thresher, transcribed in the ship's log as "900 N."
USS Skylark Ships Log, 10 April 1963, Part 3 of 3
USS Skylark communicated with USS Thresher via an underwater telephone during the deep diving sea trials.
0917: A second transmission is received, with the partially recognizable phrase "exceeding test depth...."
0918: Skylark detects a high-energy low-frequency noise with characteristics of an implosion.
0920: Skylark continues to page Thresher, repeatedly calling for a radio check, a smoke bomb, or some other indication of the boat's condition
1104: Skylark attempts to transmit a message to COMSUBLANT (Commander, Submarines, Atlantic Fleet): "Unable to communicate with Thresher since 0917R. Have been calling by UQC voice and CW, QHB, CW every minute. Explosive signals every 10 minutes with no success. Last transmission received was garbled. Indicated Thresher was approaching test depth.... Conducting expanding search." Radio problems meant that COMSUBLANT did not receive and respond to this message until 12:45. Hecker initiated "Event SUBMISS [loss of a submarine]" procedures at 11:21, and continued to repeatedly hail Thresher until after 17:00