This section of the convoy destined for the USA had separated earlier from the British ships bound for Loch Ewe, Scotland. Captain James Howard Hiss, master of the SS American Robin, was made the commodore of this American section, and his ship missed the mines. On the way to Russia earlier as part of Convoy PQ16 about six ships had been sunk by German planes, and the American Robin, carrying TNT and sailing in "coffin corner" had been dive bombed about two or three times, but escaped with near misses, causing one sailor to try to dive overboard.
I later served on the Liberty ship Martin Van Buren with Captain Hiss, but he never discussed either incident. He of course was still on the Van Buren when it was torpedoed off Halifax, Nova Scotia,in January 1945, but I had previously left the ship.
It appears that after the mine field incident involving the part of Convoy QP13 mentioned, convoys bound for Russia no longer used Iceland as a point of departure but shifted to Loch Ewe.