M-20 K (231) / Encore
Flight Crew Private; Flight Crew Instrument
Flight Crew Last 90 Days 30; Flight Crew Total 1700; Flight Crew Type 450
Communication Breakdown; Situational Awareness
Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Aircraft; Ground Incursion Runway
Flight Crew Took Evasive Action
Human Factors
I was executing a GPS approach and made 3 position reports on the UNICOM frequency; including the final call during short final. An executive jet taxied to the hold short line and then; without warning and without any announcement on the UNICOM frequency; pulled onto the runway. He then broadcasted 'rolling Runway XX with IFR departure.' This action necessitated immediate evasive action to avoid collision. Airport has an RCO. I spoke to the Supervising Controller who checked the transcript and there was no clearance void time issued for [departing airport]; hence no urgency for him to become airborne. If this event has occurred at a towered field; other aircraft would have been cited for a runway incursion. I have never experienced such a blatant disregard for established procedures and safety in my 18 years of flying.
An executive jet departed non-tower airport while M20K aircraft was on GPS approach; causing M20K to take evasive action.