Narrative:

Flying a pipeline inspection; and filming with a fixed mount digital camera. Additionally; this location is at the mexico border. The pipeline being inspected runs across the border; under a fence. As I approached from the north and was about 3 seconds from turning off the pipeline and away from the border; I noticed a helicopter coming from the south; crossing the border to my left front. I do this flight each month and always turn left for two reasons: rising terrain on the right (west); and; the camera is mounted on the left. Since I can't capture the last few hundred feet of right away and valve system at the border; I must turn off to the left and fly a teardrop back around and fly parallel with the border on my left side. I then depart the area to the north. I have never seen another aircraft in this area and I was surprised to see one now. As I got into a steep banked 120 degree left turn; at about 300 ft agl; I noticed the helicopter; instead of moving on; which I expected; had actually done a 180 degree turn and was coming back at me. I was very confused and concerned as to what it was doing. There was a ranch house in front of me which I had to avoid; the border was on my right; and an erratic flying helicopter was to my front. I rolled right out of the turn; and I wasn't sure if I had enough room to turn back west without crossing the border so I increased my turn rate and was able to roll out about 200 ft from the border and came back west and flew by the pipeline valve; filming and recording. This sequence; from spotting the helicopter to the point where I turned back north to depart the area lasted about 20 seconds; or less. I set course back to the next pipeline segment which would take me [back to base]. I lost track of the helicopter and suspected it was above me but couldn't see a ground shadow (I could see mine). The helicopter pilot contacted the tower right after I did and we had a brief air to air exchange. He had the gall to claim I turned into him twice. I did not. We parted and didn't speak again; however; several minutes later he came back on frequency and thanked the tower controller for helping him 'identify that target.' I did not appreciate that; at all.my firm belief is that this helicopter had seen me way before I saw him and not only did he not make any effort to get clear; he exacerbated the situation by making a tight 180 degree turn and coming back at me; flying so erratically that I couldn't tell what he was going to do next; giving me nowhere to go while ensuring not to overfly the ranch house or encroach on the border. In fact; I think he did it intentionally; in some ill-advised belief it's his job. If the pilot thought I was suspicious; he could have stayed a half mile away from me and observed what I was doing. The actions he took were dangerous and unnecessary.

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Original NASA ASRS Text

Title: C182 pilot reported an airborne conflict with a government helicopter at the Mexico border.

Narrative: Flying a pipeline inspection; and filming with a fixed mount digital camera. Additionally; this location is at the Mexico border. The pipeline being inspected runs across the border; under a fence. As I approached from the north and was about 3 seconds from turning off the pipeline and away from the border; I noticed a helicopter coming from the south; crossing the border to my left front. I do this flight each month and always turn left for two reasons: rising terrain on the right (west); and; the camera is mounted on the left. Since I can't capture the last few hundred feet of right away and valve system at the border; I must turn off to the left and fly a teardrop back around and fly parallel with the border on my left side. I then depart the area to the north. I have never seen another aircraft in this area and I was surprised to see one now. As I got into a steep banked 120 degree left turn; at about 300 ft agl; I noticed the helicopter; instead of moving on; which I expected; had actually done a 180 degree turn and was coming back at me. I was very confused and concerned as to what it was doing. There was a ranch house in front of me which I had to avoid; the border was on my right; and an erratic flying helicopter was to my front. I rolled right out of the turn; and I wasn't sure if I had enough room to turn back west without crossing the border so I increased my turn rate and was able to roll out about 200 ft from the border and came back west and flew by the pipeline valve; filming and recording. This sequence; from spotting the helicopter to the point where I turned back north to depart the area lasted about 20 seconds; or less. I set course back to the next pipeline segment which would take me [back to base]. I lost track of the helicopter and suspected it was above me but couldn't see a ground shadow (I could see mine). The helicopter pilot contacted the Tower right after I did and we had a brief air to air exchange. He had the gall to claim I turned into him twice. I did not. We parted and didn't speak again; however; several minutes later he came back on frequency and thanked the tower controller for helping him 'identify that target.' I did not appreciate that; at all.My firm belief is that this helicopter had seen me way before I saw him and not only did he not make any effort to get clear; he exacerbated the situation by making a tight 180 degree turn and coming back at me; flying so erratically that I couldn't tell what he was going to do next; giving me nowhere to go while ensuring not to overfly the ranch house or encroach on the border. In fact; I think he did it intentionally; in some ill-advised belief it's his job. If the pilot thought I was suspicious; he could have stayed a half mile away from me and observed what I was doing. The actions he took were dangerous and unnecessary.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.