After his capture, Machon agreed to help the United States Navy observe behaviour characteristics of fellow German prisoners of war.

On 2 October 1942, several hundred kilometers north of Cayenne (at position 06°50′N 52°25′W / 6.833°N 52.417°W / 6.833; -52.417[1]), U-512 was intercepted by depth charges from an American Douglas B-18 Bolo of the 99th Bomb Squadron.

A short time previously it had been discovered that the escape lungs had been improperly stowed and that the majority of them had become wet from a buildup of condensation in the boat.

After exiting the boat, his crewmate got confused about the direction to the surface and swam horizontally, only to lose himself between the hull and the superstructure.

Upon reaching the surface, Machon swam around for roughly 1.5 hours, unsuccessfully looking for his partner until an inflated life jacket was dropped to him from a circling airplane from the 99th Bombing Squadron.

Several times, Machon unsuccessfully attempted to attract the attention of various tankers and passing aircraft by firing his signal pistol.

At first he was very nervous giving details to the Navy officials, but then opened up after realizing Nazi propaganda about Allied torture as an interrogation method was false.

During his stay he helped Navy officials gather intelligence data on other prisoners and was extremely co-operative to his captors.