Small Aircraft; High Wing; 1 Eng; Fixed Gear
Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 258; Flight Crew Total 580; Flight Crew Type 258
Situational Awareness
Conflict NMAC
General None Reported / Taken
Human Factors
Flying a survey line approximately 4 miles northwest of HLN at 7400 ft. MSL. East to west lines. Monitoring Tower frequency to give constant updates of our position near the airport. We were operating outside of the Class D that ends at 6400 ft. MSL. We were advised there was helicopter traffic departing from HLN. My camera operator was sitting in the right seat and advised me that there was a helicopter extremely close to us. Do not know the type of helicopter. I did not see the helicopter but the helicopter advised the Tower seconds after my operator alerted me of a near miss with our airplane. Since I did not have visual before or after they advised a near miss I cannot estimate the distance between aircraft. Afterwards I asked my operator how close she estimated the helicopter to be and she could not determine but was at least closer than 500 ft. She explained she had seen the helicopter flying parallel to our flight path before turning towards us and calling the near miss.
Pilot reported a near mid air collision with a helicopter near HLN airport.