The single-prop KR2 plane is seen lowering down past the patrol car on the other side of the road during the incident on 1 August.
Trooper Clint Thompson makes a u-turn to follow the aircraft as cars slow and pull over on State Route 7 in Spanaway, 40 miles (64km) south of Seattle.
Pilot David Acklam hopped out at the lights after landing the plane
Washington State Patrol
Thompson turned his emergency lights and helped make room in the road for the plane to land, according to colleagues.
The plane is seen coming to a halt ahead of a red light at a busy junction, narrowly avoiding tragedy.
Pilot David Acklam said he was flying to work when his engine stalled, forcing him to land.
