Sigel was the commanding officer of Sturzkampfgeschwader 76 during the Junkers Ju 87dive bombing demonstration at Neuhammer, present-day Świętoszów, Poland, on 15 August 1939. Observing the demonstration were the senior Luftwaffe commanders, including Generals Hugo Sperrle, Bruno Loerzer, and Wolfram von Richthofen. The lower cloud layer, which was believed to be at 900 metres (3,000 ft), was only at 100 metres (330 ft). While Sigel managed to just barely pull out in time, 13 other Ju 87 crews crashed to their death. The event became known as the "Neuhammer Stuka Disaster" (Neuhammer Stuka-Unglück).[1]
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