Time to Replace Your Drone’s Batteries

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Battery Performance

Battery Performance Over Time

Our research indicates that aerial drone batteries need to be replaced every two to four years. This article will explain our reasoning, which may serve as guidance for your operations. For reference, we fly DJI Mavic and Phantom drones, but other drones that use Lithium Polymer technology will have similar performance characteristics.

Do You Trust Everything You Read on the Internet?

So, I go online and the first page or so of Google Search hits tell me that my DJI drone battery will last up to 30 minutes, can take 200 to 400 charge cycles, and last around two years. Well, that hasn’t quite been our experience, so we’re going to present some information that may more accurately reflect the performance you can expect.

Data From Our Flight Logs Paints a Different Picture

First of all, our flight operations are almost all commercial, primarily supporting the real estate sales and housing development markets. So, our batteries are often required to support flights at altitudes of 400 feet and speeds of 32 mph. This is a bit more demanding than flying at low altitudes and slow speeds. Thus, we shouldn’t expect our batteries to last 30 minutes. So, what should we expect?

We keep log sheets for all of our drone flights, where four years of data shows us:

1.  Our average flight times are 18 minutes.

2.  Our average battery usage ranges from 96% at beginning to 26% at end (70% diff.).

3.  For an average battery usage of 70%, we get about 3.9% per minute. (This is the same as 0.26 minutes per %, just invert.)

This information alone is probably worth your time to read to this point. However, it gets more interesting when the data is examined.

Graphing the Data Reveals Insight into When Your Batteries Need Replacement

The above graph shows that over time your batteries lose their ability to hold a charge. (Our measure of performance is flight time divided by percent battery usage). Microsoft Excel’s trend line tells us the battery’s capacity is around 0.28 minutes per percent (min/%) for a new Phantom 4 Intelligent Flight Battery. At four years, the battery’s capacity has decreased to around 0.23 min/%. This decay appears linearly related to time (not frequency of use) and for the Phantom 4 battery it indicates a 20% loss at four years.

Note the graph shows a 14-month period of no data – but the slope continued linearly indicating it’s the battery chemistry, not usage, that was driving the decay of capacity.

Key takeaway: Your typical 70% flight on day one will last about 20 minutes, and four years later will last about 16 minutes. (There are a number of factors that also contribute to battery performance including deep discharge cycles, damage from crashes, temperatures, etc.)

Mavic 2 batteries had similar graphs and similar flight times, with one important difference. The slope of their decay line was about twice that of the Phantom 4 batteries. The data analysis showed Mavic 2 batteries decay to 80% capacity at around their two-year point.

How does this Information Compare to Performance Specs on the Internet?

We believe this information is complementary to DJI’s performance spec. If you pop your drone up ten feet and let it idle, a new battery may last 30 minutes. But in more demanding situations (read real-world usage), we believe our data more closely represents your experience.

Our commercial flights have been spread across a number of batteries, so each one has a limited number of discharge cycles (less than 100). If you’re usage is significantly higher, then your batteries may lose their ability to hold a full charge at the 300-500 cycle mark, whenever that may occur. According to DJI, that may occur at its two-year mark.

Conclusions

Battery performance depends on its chemistry, which decays over time. We have shown that our Phantom 4 batteries decayed to their 80% capacity point at four years.

Data also shows our Mavic 2 batteries were at their 80% capacity point at two years. We suspect DJI traded off capacity for performance, probably by recalibrating their battery chemistry.

In addition, an aging battery gives off gases, which causes its case to swell. When your battery swells to the point that it requires effort to insert/remove from your drone, this also indicates it’s time to replace. In our experience, our Phantom 4 batteries were sufficiently swollen to warrant replacement at 4 years. Coincidentally, at their 80% point.

3D Mapping Limitations

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Mapping Failure

Failure to Resolve Shrubs and Trees

Three-Dimensional (3D) mapping with an aerial drone is exciting technology, but certain types of terrain will limit’s its usefulness. We’ll explain why some map jobs turn out good, others not so well.

Terrain Features that are Difficult to Resolve

In addition to our mapping service’s recommendation for photo set collection, we’ve found that terrain can be a significant limiting factor in the success of a mapping mission. Namely, shrubs and trees.

Many of our clients prefer terrain maps in the winter when the leaves are down so we can get ground-level elevation information. However, when the ground is covered with shrubs and trees the map doesn’t resolve very well. This is because the vegetation is too complex for the 3D processor. Remember, it’s trying to triangulate each pixel to assign its point in space. We’ve seen this even with overlaps as high as 90%/90%.

Notice the forested areas that don’t resolve well in this photo. You can see the trees have unfocused swirl artifacts. In more challenging areas, the map processor gives up and leaves the area blank. Although this picture came from our mapping service (which uses high-powered image processing), our panorama software PT Gui Pro also failed to resolve.

Other terrains such as developed properties have enough order to their colors, shades, and textures, that the map processor can triangulate the pixels. We’ve had excellent results mapping buildings, developed land, and roads.

What does our Mapping Service Recommend?

Our service includes these requirements for the photo set:

• Minimize areas with surface water

• Use an overlap of 75%/75% or better (we use 85 to 90%)

• Minimize windy conditions and long shadows

• Fly mapping missions at least 1.5 hours off solar noon

• The drone’s altitude should be at least 4 times the height of the tallest feature

However, our mapping service doesn’t have a specification for forested areas. We’ve talked about this, and they only go so far as to admit that these areas can be “challenging.”

Conclusion

We guarantee our map results and will not charge for results that our clients can’t use. However, mapping forested areas is risky for us so we may decline jobs like this. We’ll view your proposed map site with Google Maps and advise if it’s worthwhile to fly a mapping mission.

Altimeter Error’s Effect on 3D Mapping

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Aerial Drone Altimeter Error

Aerial Drone Altimeter Error

One of the specifications you won’t find for your aerial drone is its altitude accuracy. In fact, if you call the manufacturer’s support team, they probably won’t provide you with that spec. So, what do you tell a client when their mapping accuracy requirement is critical?

At FAD-Photo, we have calculated what you can expect in terms of altitude accuracy and can show you how this altitude error affects 3D mapping.

Your drone’s altimeter takes its readings from an internal barometer, does the conversions, and writes them to the photo tags, which are used by the mapping service. Mapping service providers will tell you that their numerical processing is accurate, but subject to the altitude information provided by the drone. But what if the drone’s altitude data is drifting over the duration of the mapping session?

The map processing service assumes the drone flies its mapping session in a perfectly flat plane. If the drone’s altitude readings shift during flight, then its plane shifts. This in turn shifts the ground plane causing terrain elevations to shift.

How does an Altimeter Work?

This blog is an update to our April 2020 blog Aerial Drone Altimeter Accuracy Specification. We analyzed nine months of data to refine our opinion on altimeter accuracy.

As one goes up in altitude, the air pressure goes down. The relationship between air pressure and altitude is quite predictable. So, using the formula below the altitude is easily converted from the drone’s internal air pressure sensor (a miniature barometer):

A = -(RT/gM)*ln(Po/P)

Where A is the drone’s altitude (height difference between the measurement altitude and the starting altitude), R is the gas constant, T is temperature of the air, g is the acceleration due to gravity, M is the molar mass of air, Po is the atmospheric pressure at the starting altitude, and P is the atmospheric pressure at the drone’s measurement altitude.

This formula is coded into the drone’s software so the barometer’s pressure reading can be converted to altitude. The constants R, g and M do not change, but the variables Po and P do change and are used in the calculation. The temperature T is assumed to be constant, but in reality, it’s affected by the temperature of the drone’s barometer and thus contributes to altitude error.

Over the course of a flight session, not only does the drone’s internal barometer sense pressure but it also senses the temperature effects of ambient air and heat dissipation of the internal components.

What Does the Data Tell us?

Our Flight Logs provided the record of end-of-flight altitudes for flights longer than 10 minutes. The resulting graph appears above.

The data indicate that altitude error is positive during the cooler months and negative during the warmer months. We know that average seasonal temperatures follow a sinusoidal curve, starting about 46 days after the autumn equinox (or 55 days before 1/1). Also, temperature variations are dependent on region, weather patterns, and time of day. In our case, this data was taken in central Virginia.

Developing a Trend Line

Using MS Excel’s Solver add-in, we derived the sine wave “trend line”, which follows this formula:

Altitude Error (trend line) = 2.44 + 4.74*sin((Date + 70.2)/365)

The resulting curve represents the altitude error in feet that may be expected throughout the year. The average offset is 2.44 ft plus a sinusoidal component with a peak value of 4.74 ft. The date offset of 70.2 days was expected to be closer to 55 days but is at least in the ballpark. As we collect more data, these numbers should become more accurate.

Statistical Data Calculated from the Trend Line

Other statistical data were calculated from the trend line minus the landing altitude data. We calculated a Standard Deviation of 4.60 ft and a Margin of Error of 1.14 ft (for a confidence interval of 95%). We then stacked these errors, so the expected altitude error at end of flight (EOF) is:

Altitude Error (EOF) = 2.44 +/-4.74 +/-4.60 +/-1.14 ft

Which ranges from 12.93 to -8.04 ft throughout the year

Since the drone altitude at takeoff is zero, we know this error has to build up over the course of a flight. Approximating this buildup as linear, the midpoint error is about half of the EOF altitude error:

Altitude Error (midpoint): ranges from 6.47 to -4.02 ft throughout the year

This means that for a 20-minute mapping session, the altitude error specification is around +/-6.5 ft. That is, the error can start off at zero and end at 13 ft, about a mean of 6.5 ft. The graph shows that the worst-case error can be slightly higher, but in most cases is somewhat less.

Conclusions

We take our maximum calculated error of +/-6.5 ft and round up to +/-7 ft, which we use as our altitude specification. Altitude inaccuracies affect topography mapping because our mapping service takes altimeter readings from the photo tags and cannot compensate for these errors.

For topography maps, contour lines at 10-ft intervals approach the useful limits of this technology. We can generate 5-ft contours (or less), but the overall mapping information becomes less and less useful. However, contour lines on this order may still be useful for assessing localized areas, such as slopes and structures.

Altitude error will be reduced for shorter duration mapping sessions and (as seen on the graph) near the sine wave crossings in late May and late September.

So, why won’t your drone manufacturer tell you its altimeter specification? Well, it’s complicated . . .

Precision 3-Dimensional Mapping

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Topography Map, May 2020

Topography Map Draped Over the 2-D Map

Precision 3-Dimensional Mapping

Aerial drones are the ideal method for collecting precision aerial mapping information for your land development projects. This is exciting technology and the map products that we deliver are truly breathtaking.

Each project begins with a client-provided map that outlines the site that needs to be surveyed. We enter this information into our drone’s autopilot (a mapping application), which flies the drone and collects the photos. Our typical settings are 90% overlap and 3 cm/pixel, which are further explained in our Orthomosaic Mapping and Photomapping blogs (parts 1 and 2).

We’re very good at photographing and delivering precision map products. As described below, several of these deliverables require specialized software to take full advantage of 3-D mapping. We do not offer professional cartography services, but instead provide these files to professionals who have the specialized software for these types of projects. The free software applications described below are suggested for viewing our products, but are not endorsed by FAD-Photo as suitable for professional-level mapping. We do believe, however, that many users will find them quite useful.

3-D Map Processing

Using our typical settings, the drone takes 18 photos per acre of land. For large sites, where we collect hundreds of photos, each pixel of the surface is examined at 13 or more different angles. Map processing aligns the pixels and assembles them into a 3-D composite model that includes latitude, longitude, and elevation.

Accuracy? Each photo is tagged with its position and altitude, so the composite model’s position is as accurate as the Global Positioning System. Typically, 3-4 meters.

Altitude information is based on the drone’s barometer, which has an accuracy of 3-4 meters. (We covered this specification in our April 23, 2020 blog.) Map deliverables are normalized to sea level.

Image processing is highly complex, so we use a professional mapping service provider. These are the deliverable products you will receive:

Full Color 2-Dimensional Map

This JPG file is a composite map of the photos, which are combined into a single panoramic map. Instead of a traditional scale, such as 10 meters per centimeter (or 100 feet per inch), the map service provides scale in terms of centimeters per pixel (or inches per pixel).

The JPG map doesn’t include position information, but its TIF counterpart (also a deliverable) has position information for each pixel. Use an application, such as the free QGIS software to view.

3-Dimensional Maps

DEM – Although monochrome, the Digital Elevation Model map (a TIF file) includes position and elevation information for each pixel. Special software, such as QGIS, must be used to view. The mapping service also provides a JPG of the DEM map, but this product doesn’t include position information.

Point Cloud – This is a LAS file, developed for LIDAR applications. At first glance, this full-color type of 3-D map appears fuzzy and not very useful. However, with a good viewer, such as the free Fugro Viewer, you can zoom in on the left panel image and view its corresponding 3-D model on the right panel. This is useful for looking at pixels under trees which would otherwise be masked. Of note, the 3-D model can be rotated in any direction with the mouse.

3-D Object Map – This is also a full-color map that can be rotated in any direction with the mouse. It offers a much sharper appearance than the point cloud, but it doesn’t get under the trees. Three files are required: the main 3D.OBJ file, a 3D.JPG file, and a 3D.MTL file. (You can rename the OBJ file, but don’t rename the other two.) You can open this type of map with the Windows 10 Object Viewer, but the free MeshLab viewer allows full 3-D rotation and zoom with the mouse.

Other Deliverable Map Products from FAD-Photo

The map processing report provides details on your map products, including map location, output size in pixels, scale in inches per pixel, overlap report, etc.

Topographical map (traditional contour map), where the user can specify the color scheme and contour intervals. (A postprocessing fee applies.)

Topographical map draped over the panoramic map. Here, the contour intervals are overlaid onto the full-color 2D map. An example is provided above and a larger example appears on our portfolio page. (A postprocessing fee applies.)

Do you have a special application?

Contact us for the solution. We’re experts in drone photography, mapping, and postprocessing services.

Flying Your Aerial Drone Over Water

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Flying Over Water

Flying Over Water

Flying your drone at low altitude over water can be hazardous to its health. However, there are times when professional aerial drone photographers and videographers will have to do precisely that. The drones I fly are manufactured by DJI, which discourages flying over water.

DJI Manufacturer Statements Include:

The Vision System requires clear pattern variations, with light conditions greater than 100 lux. Further, they state that users should operate the aircraft with great caution when flying over water or transparent surfaces. And specifically, Vision Positioning may not function properly when the aircraft is flying over water.

What is a Vision System?

Vision systems may use ultrasonic sensors, infrared sensors, and cameras to detect objects in close proximity to the drone. Several drone models use combinations of sensors to accurately hold altitude and to enable object tracking functions.

How does a Vision System work?

Vision systems are used for short range detection and ranging. Ultrasonic-based sensors operate at about 40 kHz and use pulsed sonar techniques to detect the nearest object. Camera-based sensors employ image processing to determine objects that not only include the ground below but also people and moving vehicles.

DJI states their vision systems rely on very sophisticated image processing to detect nearby objects. Two models that I have owned are the Phantom 3 Professional and the Phantom 4 Professional Version 2. Both employ a combination of ultrasonic and camera sensors to determine their altitude above ground.

At low altitude, the fusion algorithm prioritizes the camera sensor above the ultrasonic sensor and the altimeter (barometer). e.g. the drone’s control system maintains a certain altitude that is stabilized by its downlooking camera. The problem with flying over water is that the downlooking camera sees what the human eye will see, including objects below the surface such as the bottom.

When hovering over water (or any other transparent object), the processor may be fooled into thinking the drone is flying too high, so it orders the drone to decrease its altitude. This happens fairly quickly, which risks the drone dropping into the water.

When you Absolutely Must Fly over Water . . .

If you have to fly below 2 meters for a special shot, we recommend that you turn off the Vision System to avoid unstable movements by the drone. DJI recommends that you fly the drone at low speed and stay alert to adjust altitude.

What else could possibly cause Altitude Issues over Water?

Other physical effects could fool the drone’s processor into decreasing altitude, but only one scenario seems to fit. For an ultrasonic sonar sensor, the sensitivity time control could cause a near-water second echo to be larger than the first echo, which would read a higher altitude.

What about Sonar Returns off the Sediment?

Although sound waves can penetrate the air-water interface, the transmission loss is about 99.95% – each way! Remember, the sound has to go back through the water-air interface for another loss of 99.95%. There’s just not enough signal return to fool the sensor.

You can likewise rule out other physical effects because they would lead the processor to read a lower altitude. These include: ground effect on the barometer and the increased sound speed caused by prop wash water vapor. In other words, the processor would be fooled into increasing the drone’s altitude.

Conclusion

Flying your drone at low altitude over water can risk losing your aircraft. If you must fly under these conditions, then turn off the Vision Positioning System, maintain a minimum altitude of 2 meters, and keep a close watch on your drone.

Aerial Drone Altimeter Accuracy Specification

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Measuring Your Drone's Altitude

Measuring Your Drone’s Altitude

One of the specifications that you won’t find for your aerial drone is its altimeter accuracy. In fact, if you call the manufacturer’s support staff they won’t be able to provide you with that spec either. Technology behind the common altimeter is consistent across many of the latest airborne vehicles, including drones. In most cases, altimeter inaccuracies are minor, so these instruments serve their purpose well.

However, aerial drones operate much closer to ground than most other aviation vehicles. This is where we as drone pilots might notice a drift in reported altitude throughout our drone’s flight. We’ll explain why this drift occurs and what can be done to compensate for it.

How Does an Altimeter Work?

What we know is that as one goes up in altitude, the air pressure goes down. The relationship between air pressure and altitude is quite predictable, but subject to minor variables such as the gas content and temperature. So, whether the readout is an analog meter or a more sophisticated digital instrument, the altitude is easily converted from the air pressure. Click here for a detailed explanation on how altimeters do this.

Which of These “Minor Variables” Affect My Drone’s Altimeter?

Over the time span of a drone flight, the atmosphere’s gas content, that is Nitrogen, Oxygen, CO2, water vapor, etc., can be treated as fixed. Surface-level barometric pressure changes can also be treated as fixed. That leaves variances in temperature as the most significant contributor to altimeter inaccuracy.

Think about where the barometer is located in your drone. It’s a small sensor mounted on or near the motherboard in a relatively confined space. From the beginning of a flight to its end, heat from the drone’s control circuitry builds up in this space, affecting the barometer. Whether it’s a change in air pressure or temperature, the result is the same – a change in reported altitude.

Low Altitude Operations

This is where the thermal effect on reported altitude is more noticeable. You may have noticed when coming in for a landing that your drone is reporting an altitude of some 15 feet or so when it’s actually 3 feet off the ground. If you were to simply take off and hover, you would find that the indicated altitude slowly increases while the drone is actually in a stationary position. These are thermal effects.

Temperature drift in your drone’s altitude reading is hardly noticeable when flying high, and may only be a minor nuisance when flying low. But, where it can cause trouble is when using a programmed mode that instructs the drone to fly at a certain altitude. If that happens to be 10 feet or so, then the program will try to drive the drone at that altitude, but in reality is flying it toward the ground. Even at higher altitudes, you can lose your margin when programmed flight decreases your drone’s actual altitude above objects such as buildings and trees.

What to do When Altitude Accuracy is Important

I recently had a client that required drone photography at several specific altitudes above ground level. This job had to do with precision surveying in advance of a construction project. Since my drone’s altimeter would not meet their requirements, they set up a surveying instrument to measure the drone’s altitude (see picture). You may also consider other workarounds, such as:

  1. At the time of your critical photos/videos, record the drone’s altitude, then land and record altitude again. Take the difference for true altitude.
  2. Allow the drone to warm up for several minutes before lift-off. At the end of flight, use the reported landing altitude to estimate in-flight altitudes. (e.g. interpolate the number of feet per minute of drift.)
  3. Use an independent measurement device, such as a laser rangefinder.

Flying Your Drone in Native American Reservation Airspace

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Flying in Native American Airspace

Flying in Native American Airspace

A question was raised during my recent vacation to a National Park in Montana: Do Native American Nations have sovereign authority over their airspace? I had intended to fly the Park’s edge region from Tribal lands (which legally complies with the NPS Policy Memorandum 14-05). However, I realized the rules that apply to airspace over tribal lands might be different.

Airspace Sovereignty from the Native American Perspective

A retired chief of police of an Indian reservation (Gila River Indian Community, AZ) advised that tribal governments are very sensitive of their sovereignty and sacred grounds. He recommended that drone pilots contact the tribal government or police department and ask for permission to fly. The tribes appreciate a show of respect by asking. To sweeten the deal, perhaps you as a drone pilot could offer photos and videos that the tribe could use for its own purposes.

Unfortunately, there have been many cases of trespassers desecrating tribal lands and taking sacred artifacts. As a result, tribal governments now employ their own law enforcement officers that patrol their territory on 4×4’s. My understanding is that you do not want to be on the wrong side of a tribal LEO if you meet up with one!

Has Tribal Sovereignty over Airspace been Settled by the Federal Courts?

In my blog “Does an Aerial Drone Pilot have the Right to Fly Over Private Property?” we looked at property owners’ rights to the airspace within their property lines. It would be consistent, then, that Tribal Nations would have the same airspace rights. That is, they own the airspace up to 500 feet above ground level. This policy was affirmed in a 2016 paper by the University of Oklahoma College of Law Digital Commons “Why Indian Tribes Possess the Sovereign Authority to Regulate Tribal Airspace.” However, in this paper, an argument was made that Tribal Nations own ALL of the airspace within their boundaries.

Of course, such an assertion by tribal governments conflicts with federal regulations and FAA jurisdiction. However, the author makes a good point that Native American Nations enjoy significant sovereignty in other areas of the law. Since the airspace jurisdiction question had not been resolved as of 2016, drone pilots should contact tribal authorities and request their permission to fly.

No Fly Zones – Flying Your Drone in Restricted Airspace, Update

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FAA Drone Zone

Unlocking an FAA No Fly Zone

For several years, the more expensive aerial drones on the market have been designed with built-in firmware that prevents start-up of the motors if the drone is in an FAA restricted airspace, also known as a no-fly zone (NFZ). These zones are typically found around airports, heliports, prisons, military installations, etc.

Here’s the latest information on No Fly Zones, updating my blogs (Part 1 and Part 2) posted last year.

Identification of No Fly Zones

The easiest way to determine if your intended flying area is in a No Fly Zone, is to check with one of the drone manufacturers’ web sites. For example, DJI posts their NFZ map online at this link. If you haven’t checked the map and you find your drone acting odd, you might be in a NFZ. Odd behavior means it won’t start up or it won’t fly past an invisible barrier.

FAA Permission

If you know your intended flying area is in an NFZ and you need access for a valid reason, there’s a way to get permission. You start with the FAA, which has a new web site portal called the Drone Zone that allows you to ask for airspace authorization.

Enter the information and the FAA will turn around their response in just a few days. Be prepared to offer a good reason for your request. If you’re Part 107 certified, your drone is registered, and you have a valid tasking from a client, then your approval will likely be straightforward.

The FAA will contact the appropriate authority, such as the airport’s Fixed Base Operator, who may come back with restrictions such as flight times, flight days, max altitude, etc. Or, you may be declined. If all goes well, the FAA will issue you a signed form (PDF) authorizing your flight plan.

Drone Manufacturer Unlocking

Submit that form to your drone manufacturer. For example, if your drone was manufactured by DJI, then go to their “Unlock a Zone” portal at this link. Enter the information and the manufacturer will turn around their response in just a few days.

In my experience, the process has been quite fast, with same-day approval from both the FAA and DJI. Once the drone manufacturer has approved your request, they will provide a method to download a firmware patch to your drone. Activate the patch using your drone’s control software. Your permission will typically include a geoposition and date range.

Your Rights to Retrieve a Drone If It Lands On Private Property, Part 2

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What If An Irate Property Owner Has Your Drone?

What If An Irate Property Owner Has Your Drone?

Aerial drones are usually reliable, and in the hands of an experienced operator are brought home with sufficient battery power in reserve. However, there may be circumstances when the aircraft can’t be brought home and it lands on someone else’s property. I established in Part 1 that the property owner does not have a lawful claim on your aircraft. In this blog, we review your recovery options in less-than-friendly circumstances.

What Are My Options?

If the property owner refuses to return your aircraft, or allow you to retrieve it, then you should call local law enforcement to intervene. As long as no harm was done, then it’s likely that the property owner will hand over your drone to a law enforcement officer. Although the owner may be reluctant, they may come around after being advised that they face a charge of larceny if they hold onto it. There are several other ways this scenario can play out (such as intentionally destroying your aircraft), but if none turn out favorable to you, then you’ll have to ask for a law enforcement report and proceed with a civil or criminal complaint.

I recently heard of a scenario where a novice was using their drone for low-level spying, which violates state and federal privacy laws. If the property owner gets your drone under these circumstances (using any available means) your claim is going to be an uphill battle.

If your aircraft gets stuck in the owner’s tree or is on their rooftop, then be prepared to pay for a service to come out to retrieve it for you. For example, this may cost you $150 for a tree service to come out, climb the tree, retrieve your drone, and assure the owner that no harm was done to their tree.

Sometimes the best grease is money. If the property owner is annoyed, then you may offer a modest sum for their troubles. Conversely, if the property owner demands a “salvage” fee, then this may be the path of least resistance that gets your aircraft back. Even if the law of ownership is on your side, getting a legal judgment will be costly and take time. In the meantime, you’ll probably have to buy another drone.

There is the unpleasant scenario where your drone damaged property or injured a person (or animal). In such a case, your drone deprived the owner of their full enjoyment of the land and your situation has become a whole lot more complicated. This is why you need a good liability insurance policy.

What if the Property Owner Refuses to Return My Aircraft?

Aerial drones can be expensive, with the value of some in the thousands of dollars. At this price point, a court proceeding may be worth the cost. For less expensive drones, a court proceeding may give you some degree of satisfaction but the cost may exceed the drone’s value. Some property owners are so belligerent that they will destroy your drone. I wish I could be gentler in advising that you may need to be prepared to accept the loss of your drone.

In Any Scenario with Complications, Document Everything and Take Pictures

If your operations require flying over private property, then carry an insurance policy that covers liability AND loss of aircraft. If it goes down, then collect as much information as possible about the circumstances, take pictures, print out your controller’s log files, and take names. When dealing with property owners, always be professional and affirm their rights as well as your own. Even though the law is on your side, the property owner has possession of your drone so carefully assert your rights in the kindest manner possible.

Your Rights to Recover a Drone If It Lands On Private Property, Part 1

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Did Your Drone Come Down On Private Property?

Did Your Drone Come Down On Private Property?

Aerial drones are usually reliable, and in the hands of an experienced operator are brought home with sufficient battery power in reserve. However, there may be circumstances when the aircraft can’t be brought home and it lands on private property. Does the private property owner have a lawful claim on your drone? In Part 1, we review your recovery options in relatively cooperative, no-harm circumstances. In Part 2, we’ll review your recovery options in less-than-friendly circumstances.

What Could Possibly Go Wrong?

First, let’s review some of the circumstances that are covered in this blog: (1) unexpected mechanical failure, such as a battery issue, electronic failure, or motor/propeller malfunction; (2) loss of control, such as an automatic return to home at too low of an altitude and it crashes into an object; or (3) forced landing due to an exhausted battery.

Please note there are a number of circumstances not covered in this blog. Primarily, these are activities that might deprive the property owner of the full enjoyment of their land, including evidence of: (1) the drone is causing a nuisance: (2) being flown recklessly; or (3) violating a state privacy law. For whatever reason an aircraft may come down under these circumstances, your rights may be compromised. Please read my blog on flying over private property. In addition, if your aircraft enters controlled airspace and a law enforcement or military activity takes it down, you’ll have an uphill battle getting it back.

Do You Still Own Your Drone?

Case law is well settled that ownership of your property is retained, regardless of where that property may be situated. Conversion of lost property doesn’t occur unless it remains unclaimed by the owner. So, for a property owner to cite conversion (that is to assume ownership), they must post a notice of “found property” or turn it over to law enforcement for a period of time, typically 3 months.

So yes, you have the right to recover your aircraft from a property owner. This doesn’t mean that you can intentionally trespass, especially if the owner is standing there with a shotgun, or there are other obstacles such as dangerous animals. But you do have the right to ask for the return of your property.

How Do You Get Your Drone Back?

If you know where it landed, then you should introduce yourself to the property owner, identify yourself as the drone owner, and ask for its return. The owner may be annoyed, but a reasonable explanation of how it ended up on their property will be helpful. Further, if it has an FAA registration number and other identifying information, then you have established your right of ownership. Don’t forget that your controller also establishes ownership, simply proven by operating the drone; e.g. moving the camera, starting the motors, etc.

Of course, there may be other scenarios where the property owner is less cooperative. These include situations where your aircraft is stuck in their tree, on their roof, or has caused damage. There may also be scenarios where the property owner is just plain uncooperative. We’ll address those in Part 2.