 A large number of paratroop drop aircraft were hit and lost as well . This was largely due to the hostile conditions encountered by the drop aircraft . Operation Varsity 's paratroop drop phase was flown in daylight at slow speeds at very low altitudes , using unarmed cargo aircraft , over heavy concentrations of German 20 mm , 37 mm , and larger calibre antiaircraft ( AA ) cannon utilizing explosive , incendiary , and armor @-@ piercing incendiary ammunition . By that stage of the war , German AA crews had trained to a high state of readiness ; many batteries had considerable combat experience in firing on and destroying high speed , well @-@ armed fighter and fighter @-@ bomber aircraft while under fire themselves . Finally , while many if not all of the C @-@ 47s used in Operation Varsity had been retrofitted with self @-@ sealing fuel tanks , the much larger C @-@ 46 Commando aircraft employed in the drop received no such modification . This was exacerbated by the C @-@ 46 's <unk> wings , which tended to pool leaked gasoline at the wing root where it could be ignited by flak or a stray spark . Although 19 of 72 C @-@ 46 aircraft were destroyed during Operation Varsity , losses of other aircraft types from AA fire during the same operation were also significant , including 13 gliders shot down , 14 crashed , and 126 damaged ; 15 Consolidated B @-@ 24 bombers shot down , and 104 damaged ; and 30 C @-@ 47s shot down and 339 damaged . 
