Three Ukrainian pilots were killed on Aug. 25 when their planes collided in the sky, the Air Force confirmed on Aug. 26.
Among the dead is a well-known pilot from the 40th Tactical Aviation Brigade, who had the call-sign Juice.
The pilot had over 14,000 followers on Twitter and frequently used his platform to advocate for the provision of F-16s to Ukraine.
The crash involved two L-39 training jets that were flying above Zhytomyr Oblast.
"This is a painful and irreparable loss for all of us," the Air Force said in a statement, and expressed condolences to the pilots' families.
The State Bureau of Investigations said that it has started a probe into the accident to find out what went wrong.
The bureau will investigate "the technical condition of the aircraft, compliance with the rules of preparation for flights," and the black boxes of the jets.
"The loss of each soldier is a huge loss for the entire country," the Bureau said.
The preliminary investigation has assessed there may have been a violation of flight rules or preparation for the flight. The crime carries a punishment of up to 15 years in prison, according to Article 416 of Ukraine's Criminal Code.
Anastasiia Lapatina
