Su-27UB fighter aircraft crashes at Clear Sky 2018 Published Oct. 16, 2018 USAFE-AFAFRICA Public Affairs Khmelnytskyi region, Ukraine -- We are aware of a Ukrainian Su-27UB fighter aircraft that crashed in the Khmelnytskyi region during Clear Sky 2018 today. The incident is currently under investigation and do not have any other information to provide at this time. We will provide more information as soon as it becomes available.