Captain Lachnit was the pilot of a B-26B with Headquarters Squadron, 452nd Bomber Wing at Pusan Airfield East (K-9), South Korea. On 21 February 1951, while on a night intruder mission, the aircraft reported clear weather and contact was lost. He was listed as Missing in Action and was presumed dead on 31 December 1953. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Lachnit was awarded the Air Medal with Oak Leaf Cluster the Purple Heart, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal, the Korean Presidential Unit Citation and the Republic of Korea War Service Medal.