Gromotka was born on 2 June 1915 in Kronschkow, present-day Krążkowy, in the Prussian Province of Posen within the German Empire.

[1] In November 1940, he was posted to 6./JG 27, and during the Balkans Campaign of March–April 1941 claimed three victories over Greece, including two RAF Bristol Blenheim bombers of No.

In March 1944, III./JG 27 departed the Mediterranean for Reichsverteidigung duties and deployment in June to the Normandy Invasion front.

[5] According to Obermaier, Gromotka was credited with 29 aerial victories claimed in 438 missions, and included 10 four-engined heavy bombers.

[1] Mathews and Foreman, authors of Luftwaffe Aces — Biographies and Victory Claims, researched the German Federal Archives and found records for 22 aerial victories, plus seven further unconfirmed claims, achieved in 438 combat missions.

The Luftwaffe grid map (Jägermeldenetz) covered all of Europe, western Russia and North Africa and was composed of rectangles measuring 15 minutes of latitude by 30 minutes of longitude, an area of about 360 square miles (930 km2).