Date: 202107
Local time of day: 1801-2400
Location: WHP.Tower, CA
Flight conditions: VMC
Weather elements / visibility: 10
Light: Night
Aircraft: Small UAS (At or above 0.55 lbs and less than 55 lbs)
Operator: Recreational / Hobbyist (UAS)
Operating under: Recreational Operations / Section 44809 (UAS)
Flight plan: None
Mission: Recreational / Hobbyist (UAS)
Flight phase: Hovering (UAS)
Airspace: Class E ZZZ
Second aircraft: Helicopter
Reporter organization: Recreational / Hobbyist (UAS)
Reporter function: Remote PIC (UAS); Person Manipulating Controls (UAS)
Reporter qualification: Flight Crew Private
Anomaly: Airspace Violation All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Unauthorized Flight Operations (UAS); Deviation / Discrepancy - Procedural FAR
Detector: Person UAS Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action; General Police / Security Involved
Contributing factors: Human Factors; Chart Or Publication
Primary problem: Ambiguous

Narrative: At approximately XA20 on Date I was flying an FAA registered UAS (drone) in what I believe to be a lawful manner. I was operating it under the recreational waiver which permits nighttime operations that went into effect this year. It was night time and it had a federally mandated light source on top to be visible by 3 miles. The night was exceptionally clear. VNY visibility was 10 or more miles; Sky Clear below 12;000 feet.The drone is also equipped with positional lights to be aware of the attitude and direction of flight. These are visible to more than a mile away.I maintained the UAS was also less than a mile away at its furthest and no more than 1;500 feet away during the hover sequence with the helicopter.During the entirety of the flight; the drone was operating at no more than 205 feet above the operator and only that for only about a minute during a rotation to maintain antenna connectivity. This is well under the 400 feet air regulation.The drone was only above vehicles; people or property in a transitional manner except when the helicopter forced me into a hover. It did not interfere with the emergency services; but they approached the drone to investigate it and me.The drone; due to the lighting; was always within VLOS without visual aids; and in fact; the point of the exercise was to determine the VLOS at night. Incremental altitude adjustments were made to maintain safe altitude and VLOS separation from the background.I was outside of the class D airspace of Whiteman airport; in Class E; and maintained the aircraft visually to the north of me in a straight line. There were no NOTAMS or TFRs.  Aloft and B4UFly both showed things as clear as long as I remained outside of the Class D. The drone received its geo unlocking license from Whiteman via the app. I also listen to Whiteman ATC on LiveATC.I was also well below the landing pattern for Whiteman long straight-in approaches as an additional measure of safety; as I know many aircraft into Whiteman do not enter the pattern on the downwind; but simply report 3 mile final. The UAS is equipped with ASB-B. I did not receive an ADS-B notice that an aircraft was in the vicinity. Nor were any other aircraft operating in the immediate area at the time visually.I had just completed my VLOS test. I had rotated the aircraft to return home. A few seconds later; I heard an approaching aircraft. Review of my video during the rotation shows the helicopter in the distance when I turned to return home; but I was watching the drone visually; not via the screen. The helicopter does not appear to be going intentionally towards the drone. The helicopter appears to be about as far south as the 118 freeway at the time I was already coming home; given it is farther away than the San Fernando lights along San Fernando and Truman.Upon hearing the aircraft; I quickly lowered its altitude to 35 feet above me. I initiated the descent about 17 seconds after I had already begun to return home.The helicopter did not fly to initially intercept the UAS.I was unaware of what sort of aircraft it was at the time (GA airplane; news; police; etc); but assumed helicopter.This 35 feet was a minimum altitude to ensure connection (a connection loss would send the aircraft up to safely return home and that needed to be avoided under the circumstances); avoid trees and poles; and to maintain direct VLOS while being safely below any low flying aircraft. During the rapid descent; I covered almost half the distance back. The entire flight was only about 4 minutes; including hover pauses.This was done to safely avoid any potential aircraft and not interfere with any emergency service.Even if I had maintained the original altitude; I still would have been below the helicopter.When I saw the helicopter approach; I stopped forward motion to not present a problem for the helicopter or interfere. Video at the time seemed to show the helicopter examining an area to my east from severalhundred feet above the drone. It was using a night sun to illuminate several houses. At the time; it appeared the helicopter was high enough above me to not be a danger and not in my direction of travel.I had to gimbal the camera up and rotate to get the helicopter in view of the drone camera (I could see both aircraft myself from my vantage point).Although it seems more obvious from the drone's point of view; I could not immediately tell the helicopter had disengaged from its original intent (if there was one) and was now tracking my UAS. Each time I saw the helicopter start to leave; I got the UAS closer to home. The drone; at the time; was only 35 feet up. This was the altitude it stayed at the entire time the helicopter was nearby; so there was no danger of actual collision; but the helicopter pilot; once aware of the drone; behaved recklessly. When it was obvious that the drone was not a threat to the operations of the helicopter due to the height differential and realizing that the helicopter was both aware of me and now harassing me; I brought it home and landed it. The orbiting of the helicopter forced me to hover the drone possibly over property; which presented a potential danger.After landing; the [pilot] on the airship orbited my house and proceeded to threaten me by speaker that 'If you want to keep that drone; I suggest you not fly it again.' which I find remarkably unbecoming. [The pilot] also said  'Next time; I'll send [someone] over to take it.'  It then orbited my house more and then left the area; abandoning whatever it was initially doing. I don't know if [the pilot] thought I was a child and was threatening to take my toy away; but I consider this threat to be unprofessional and outside of the guidance from the FAA; at the very least.I was operating my UAS with safety considerations and the federal air regulations in mind; including additional lighting; and I behaved in all ways to maintain the safety of all flight operations. As the PIC; I did what was necessary to maintain safety for everyone.  The whole exchange as initiated by the helicopter was also potentially dangerous and a waste of resources.




Synopsis: UAS pilot was flying at night and had an airborne conflict with a helicopter.