https://inciweb.nwcg.gov/incident/article/5514/38527/

Miller Complex, August 19, 2017

An unauthorized incursion by two non-mechanized gliders occurred over the Miller
Complex this afternoon in an area where aircraft were assisting with
firefighting operations. This incursion caused fire mangers to ground all of the
aircraft for 45 minutes due to safety concerns. The operators were located.