The first Me 321 A-1 production aircraft entered service in May 1941 with Grossraumlastensegler 321 at Leipheim , initially towed by Ju 90s and later by the He 111Z and the '' Troikaschlepp '' arrangement of three Bf 110s . The triple Zerstörer arrangement was very dangerous in the event that one or more of the takeoff booster rockets failed . One such failure did occur in 1941 , which led to the collision of the tow-planes and the deaths of all 129 occupants of the four aircraft . This accident was the deadliest in the history of aviation at the time . The death toll would not be matched until the Tachikawa air disaster of 1953 and would not be exceeded until the 1960 New York mid-air collision . The later Me 321 B-1 variant had a crew of three and was armed with four 7.92 mm ( .312 in ) MG 15 machine guns
Tachikawa air disaster
Tachikawa air disaster
Messerschmitt Me 321