Complex sentence: The prototype GW-3 was involved in an accident on 30 June 1993 when downdrafts were encountered in mountainous terrain, it was unable to return to the airport and crashed, resulting in a serious injury to the pilot.
Split into simpler sentences: The prototype GW-3 was involved in an accident on 30 June 1993 when downdrafts were encountered in mountainous terrain. The aircraft was unable to return to the airport and crashed, resulting in a serious injury to the pilot.