11 Jun 1944
At 02.05 hours, the boat opened fire at an aircraft that flew directly over her at a height of 40 meters about 40 miles southwest of Bergen. It was hit and crashed into the sea after answering the recognition signals too late. The men aboard U-243 realized that they had shot down a friendly Ju88 aircraft, headed at full speed for the position where the aircraft sank and picked up the sole survivor from the crew of four, the radio operator. U-1000 joined the rescue operation after observing the downing of the Ju88 shortly after it had exchanged recognition signals with this U-boat, but only found a torn up rubber dinghy. The survivor was landed at Bergen on 12 June. (Sources: BdU KTB)

8 Jul 1944

The sinking of U-243: At 14.35 hours, the boat was attacked by the Australian Sunderland W4030 (10 Sqdn RAAF/H, pilot FO William B. Tilley) in the Bay of Biscay and opened AA fire on a range of 2 miles. The approaching aircraft strafed U-243 with 1250 rounds, wounding at least three men on the bridge including the commander and silencing the AA guns. Six depth charges were dropped and straddled the stern. The explosions disabled all engines and opened a big leak, causing the stopped U-boat to settle by the stern with a list to port. AA fire kept the Sunderland on distance until the Germans began to launch dinghies at 15.00 hours. The abandonment was hastened by the arrival of a second Sunderland from the same squadron and an American Liberator, which both dropped depth charges on the already sinking U-boat. Tilley dropped a dinghy and a food pack for the survivors before returning to base. He was awarded an immediate DFC, while the front gunner FSgt Lance E. Cooke received an immediate DFM. Märtens and 38 survivors were picked up by HMCS Restigouche after 14 hours, but the commander later died of wounds.

2 recorded attacks on this boat.