Hintze states that all the German pilots involved expressed regret for shooting down a civilian aircraft and were "rather angry" with their superiors for not informing them that there was a scheduled flight between Lisbon and Britain. Goss writes that official German records back up Hintze's account that "Staffel" 14/KG 40 was carrying out normal operations and that the day's events occurred because the U-boats could not be found. He concludes that "there is nothing to prove that German pilots were deliberately aiming to shoot down the unarmed DC-3." This account of the German pilots and Goss's conclusions are challenged by some authorities.