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Here is a question I get on a regular basis.
How far can we fly our drone at the incident scenes and how far beyond the line of sight can we go?
You would think there would be a simple answer to this question. There actually is but the facts get clouded with a lot of incorrect assumptions by inexperienced pilots.
Current drone flight within the visual line of sight is controlled by CFR 107.31. The only way to fly a drone under Part 107 without having VLOS on the drone (even for public safety) is to obtain a waiver to regulation 107.31 from the FAA. VLOS to the FAA means something much more substantial than just being able to barely distinguish it. The regulation requires you have to see it well enough to distinguish certain specific criteria about the drone and the flight.
Even departments flying under a COA must still maintain the Visual Line of Sight (VLOS) of the aircraft if the pilot can’t see it. The Beyond Visual Line of Sight (BVLOS) component only refers to the pilot’s inability to see the aircraft, but the Visual Observer (VO) must still maintain eyes on it. If you don’t believe that statement, listen to my COAcast with the FAA here. You can start listening at 18 minutes.
§ 107.31 Visual line of sight aircraft operation.
(a) With vision that is unaided by any device other than corrective lenses, the remote pilot in command, the visual observer (if one is used), and the person manipulating the flight control of the small unmanned aircraft system must be able to see the unmanned aircraft throughout the entire flight in order to:
(1) Know the unmanned aircraft’s location;
(2) Determine the unmanned aircraft’s attitude, altitude, and direction of flight;
(3) Observe the airspace for other air traffic or hazards; and
(4) Determine that the unmanned aircraft does not endanger the life or property of another.
(b) Throughout the entire flight of the small unmanned aircraft, the ability described in paragraph (a) of this section must be exercised by either:
(1) The remote pilot in command and the person manipulating the flight controls of the small unmanned aircraft system; or
(2) A visual observer.
The Light Bulb Went Off For Me
The day it all clicked for me I was shocked at how badly I and others had violated the CFR 107.31 during the day and especially at night.
In order to fly within the regulations, I needed to meet all the requirements of CFR 107.31. In order to do that I would need to see more than a dot in the sky. Being able to see the drone only does not make you within the regulations.
If that was the case, then how far can you really fly during the day and at night and remain legal? The only way to know for sure was to test.
Robert Zarrancia and Bruce Christianson in Minnesota volunteered many hours to conduct this testing. They flew multiple aircraft during the day, night, and civil twilight. The temperatures were very cold and there were many days when testing had to be postponed due to winds.
The goal was to conduct the measurements in an environment to give us a real-world baseline. These pilots took one for the team to conduct their research and document their results. We owe them a debt of gratitude.
Without Further Delay – Night Flight Distances
Let’s start with the really bad news. Night flight.
A misperception people have is that as long as the pilot can see the strobes on the aircraft they are within VLOS. That is not true. VLOS is determined by a series of observational requirements. As the FAA has pointed out, the strobes are not for the UAS pilot, they are there to warn other aircraft in the sky.
Flying both a DJI Mavic and Phantom 3 the actual distance at night for the regulation-compliant flight was within about 40 feet up and 65 feet out.
For any data point in this discussion, I welcome you to go out and measure the distances for yourself to maintain all the required observations required in CFR 107.31.
This reality now makes it clear why the FAA adds the following statement to all CFR 107.29 waivers to fly at night: “The area of operation must be sufficiently illuminated to allow both the remote PIC and VO to identify people or obstacles on the ground, or a daytime site assessment must be performed prior to conducting operations that are the subject of this Waiver, noting any hazards or obstructions.”
It would appear the FAA means what they say in that waiver requirement for night flight. To comply with CFR 107.31 you would need to light your flight area or it is limited to a very small range.
Flight During the Day
In testing, it was discovered that compliant flight was complicated. There were several issues that impacted flight distance.
If the VO lost contact with the aircraft, the drone had to be flown back towards the VO to regain contact and CFR 107.39 compliance.
For the Mavic and Phantom 3 the total flight distance under the best of circumstances was less than 1,250 feet if the aircraft was above 200′ Above Ground Level (AGL).
If VLOS was lost with the aircraft, it was unable to be accurately recaptured until it was within a 450 foot to 900 range from the VO and/or PIC if they were closely colocated.
The lower contrast the sky or background was, the more the distance was reduced.
What the Testing and Data Tell Us
Put your beliefs aside for a moment and just try to square the facts with reality. CFR 107.31 requires us to maintain those required observational items to be compliant with VLOS flight. COAs and even a Tactical BVLOS waiver all require VLOS by a VO if the aircraft is BVLOS for the pilot.
Night flight distances would be no higher than 40 feet or further than 65 feet from the VO, even with strobes on during flight.
During the day flight should not be more than 1,200 feet if you are using a VO that has not lost contact. If you are flying as a Part 107 pilot without a VO, you are required to maintain VLOS at all times but if you do look away, testing data showed that the safe flight distance was 400′ AGL and about 500′ from the responsible party watching the aircraft.