Drone regulations: where we are today, where we’re going and what you need to know

New technology opens a door to evolving regulations around it. Think of the car over the past 100 years. At first, there were no speed limits, no safety belts and no traffic lights. Now traffic and license regulations are sophisticated and particular to every country. In fact they’ve become a normal part of our everyday lives. Such is the case with drones and airspace. The next two years will see a leap forward, specifically in European drone laws that you as a user will be well-situated to understand.

In this article, we focus on drones for commercial use. We offer a view of now and what is visible on the horizon of drone legislation. This is a complex topic, because drone rules and regulations depend on the evolution of commercial drone technology; real and imagined risk factors, and use cases that inspire new rules and exceptions. Additionally, while rules for flying drones might be transparent and well-documented in some parts of the world, it’s important for users to check with local aviation authorities when flying drones in a location.

What you need to know about drone regulations today

To frame drone flying laws effectively in this article, we’ll target two large and influential markets: Europe and the United States. In Europe, the European Union Aviation Safety Agency (EASA) oversees and develops the rules applicable to the design, manufacture and operation of drones. In the United States, the Federal Aviation Authority (FAA) holds the same jurisdiction as the EASA does in Europe.

In the US, the FAA has had formalized regulations in place since 2016, while in Europe, the EASA is now phasing in similar ones. By 2023, European operators and drone manufacturers need to be on board with these.

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In both the US and Europe, when a user wants to fly a drone for a project, the risk factors will determine what they need to do to operate within drone flying laws, and if it is even possible within regulations. Specifically, the altitude, whether there are people in a defined vicinity and whether or not the drone remains visible to the operator at all times define the scope of risk. Depending on its weight and purpose, the aircraft as well must conform to rules, which are constantly evolving.

Worldwide, this basic framework generally applies, yet you will find that there are nuances in every country, with some being more conservative and others being less formal, or even non-existent. See the resources section at the end of this article for more information.

What are drone regulations?

• Drone regulations (or commercial drone laws) are rules put out by a government branch in charge of airspace management and safety
• Regulations exist at the national level yet EASA is working to harmonize rules across the entire European region
• Commercial drone regulations evolve, and it is up to users to inform themselves about specific requirements for the operator and the drone in order to conform to the regulations
• Operators can fly certain types of drones in low-risk situations with minimal training and restrictions
• Once the flight involves more risk factors, more training and paperwork must be completed to ensure safety and legal operations

How to know when you need to get more permissions

Baseline operations in low-risk situations

One thing we can say is pretty universal is the lowest risk category for operating a drone. According to the EASA, this is called the “open” category. And according to the FAA, it’s called “Part 107.” For both territories, the lowest-risk parameters are the same: fly no higher than 120 m (or 400 ft), at a safe distance from people with the drone in visual line of sight (VLOS) at all times.

These low-risk parameters ensure that the drone (according to its maximum altitude) does not interfere with other air traffic, does not pose risk to bystanders and is under supervision of the operator (VLOS).

To fly a drone in low-risk situations in the US and Europe, a pilot needs to pass an aeronautical knowledge test or online theoretical knowledge exam, respectively. Then, if they are flying in the US, they will need to register their drone. And if they are flying in Europe, they will need to register themselves as an operator, plus the drone must have a C-marking starting January 2023 (see product conformity section below).

Note: In Europe, a registered operator can also be a company operating multiple drones via multiple pilots. 

Whether a mission is low or high risk depends on a range of parameters including flight altitude and whether or not the mission takes place in a populated area.

Flying drones in higher-risk situations

Once you need to fly a drone in riskier situations—e.g., higher altitudes, around more populated areas or beyond visual line of sight (BVLOS)—the category changes, and so does the process.

In the EU, in medium-risk situations, the “open” category becomes the “specific” category, and you will need to provide a Specific Operational Risk Assessment (SORA) to the national aviation authorities of your country. You’ll bring this to the aviation authorities. If your SORA application is approved, you can fly within these parameters as needed/specified.

In the US, you will need to apply for a Part 107 “waiver.” Basically, you need to analyze the risk for your specific operation and demonstrate to the FAA that this risk is acceptable. If you succeed, you will get a waiver for the mission at issue or any mission like it.

In high-risk situations—for example, carrying passengers, or carrying dangerous cargo—you need both certification of the drone and operator. This applies in Europe and the US and is technically the certified category of operation.

What about drone compliance?

In the United States, the FAA classifies “small drones” as those weighing less than 55 lbs (25 kg). As the operator, you are responsible for ensuring that the drone is safe before flying it. In other words, the FAA does not require small drones to comply with airworthiness standards or to obtain aircraft certification. This puts responsibility on the operator to, as the FAA website recommends, perform inspections and check communication links between the base station and drone, regularly.

Additionally, the FAA has the right to inspect the drone or test it on request, and you may need to provide records of the work you are doing with it. If your small drone flight results in serious injury, loss of consciousness or property damage of more than 500 USD, you must notify the FAA within ten days.

In Europe, the new drone regulations that are taking shape around drone compliance are more involved. These are being rolled out over the next two years so that drones meet specifications and affix labels accordingly. For the low-risk “open” category, drones fall within sub-classes according to their weights from C0 to C4. Within the low-risk “open” category of flying, there are three subcategories: A1, A2 and A3. Drones in certain classes can fly in certain categories. Similar to the US, operators need to report any safety-related issues to their local aviation authority in a timely way.

While subcategory is important to consider, it’s also important to look at the regulations according to the types of missions you will fly regularly and their logistics

Where can I fly my drone in Europe?

• A1 for drones less than 250 g (0.5 lbs).You can fly VLOS over people but not open-air assemblies). This category applies to toy flying objects designated for use by children under 14 years of age.
• A1 for drones that weigh less than 900 g (1.98 lbs). You can fly VLOS but avoid flying over people.
• A2 (you can fly VLOS close to people).If your drone is 4 kg (8.8 lb) or less and meets specific product requirements you can fly it a minimum horizontal distance of 30 m (98 ft) from uninvolved people or within 5 m (16 ft) in a low-speed mode if the pilot has successfully taken an additional competency exam.
• A3 (you need to keep a distance of 150 m/492 ft from urban areas during VLOS flight).This will apply to unmanned aircraft with the intent of making sure that they fly in areas that are clear of uninvolved people and not in what is called congested areas in today’s terminology.

Regarding A2/A3 regulations: for mapping drones that offer wide coverage, the main implications are practically the same since these UAVs cover large areas, which must be free of people.

Which drone class can fly where in Europe?

Class	Sub-category	General considerations
C0	All	Less than 250 g (.55 lb) Max speed 19 m/s (42.5 mph) Flight limited to 120 m (400 ft) above take-off point No need to register yourself unless it has a camera and/or is not a toy
C1	All	Less than 900 g (2 lb) Transmits less than 80 joules of energy if struck someone’s head Has a remote identification system Designed and built to minimize injury Max speed 19 m/s (42.5 mph) You must register as a pilot
C2	A2 or A3*	Less than 4 kg (8.8 lb) Designed and built to minimize injury Has a remote identification system Has a low speed mode, limiting speed to 3 m/s (6.7 mph) You must register as a pilot
C3	A3	Less than 25 kg (55 lb) Possesses automatic control models Has a remote identification system Has a geo-awareness systems You must register as a pilot
C4	A3	Less than 25 kg (55 lb) No automation features other than for basic flight stabilization (e.g., traditional model aircraft) You must register as a pilot

It’s important to note that the subcategory can change based on an application. In the case of mapping drones, the mapping area invites many opportunities to come closer to people or fly directly overhead. In this case, the 30 m (98 ft) distance is an entire radius around the drone spanning to all sides and directly down to the ground. Additionally during flight, a minimum horizontal distance equal to the flight height shall be kept. In other words, this distance surrounds the drone like a massive bubble with the required distance surrounding it on all sides (the so-called 1:1 rule).

WingtraOnes on the market now are compliant to fly in the states and Europe even after the January 2023 regulations officially start. From January 2023, all WingtraOnes sold will be affixed with a C3 label.

So what do we do now?

In the US, it looks like not much is changing in the immediate future. However, in Europe, operators and drone manufacturers have the next two years to become compliant in terms of the training that they need and the compliance of their equipment, respectively. In the open category, for category A3 drones, like WingtraOne, equipment sold before 2023 can still be operated beyond 2023.

In Europe, operators need to be registered and pilots need to have passed the required online knowledge tests by December 31st, 2020.

If you are flying in Europe, and not in an open category situation, you’ll want to begin the SORA application process with your local aviation authority.

If you plan to fly missions that fall in the open category, you’ll also want to check with your drone manufacturer that their current model of drone is compliant with the subcategory of conditions you plan to fly in. This means it conforms to regulations, and by 2023 has both a genuine CE and a C(0,1,2,3, or 4) class label affixed to it based on its approved classification.*

As new drone laws get clearer, more uncertainties will arise, leading to more clarification and more sophisticated regulations. Again, think about automobiles and motorcycles, with their different classes, evolving safety standards, and all the license and registration requirements we consider normal.

The same will emerge for drones and pilots as airspace regulations grow more detailed. It’s an exciting time. And we, at Wingtra, are happy to say that our engineers are working with these changes in mind so that customers experience a smooth transition as regulations formalize.

*Drones purchased before 2023 may comply with formalized regulations, and firmware updates may be provided to allow the C-class marking on these older drones.

Source: https://wingtra.com/drone-regulations-where-we-are-today-where-were-going-and-what-you-need-to-know/

Ground control points: How many do you need (and when are checkpoints enough)?

Ground control points (GCPs) are fundamental tools in GIS and surveying. Sometimes GCPs are not needed, e.g., when surveying results are only for relative accuracy or to assess some details of an area by themselves. But when your aerial survey must feature absolute location accuracy—i.e., all points on the map have geo locations that tightly align with the points on Earth they represent—GCPs are a way to help ensure that accuracy.

When do we need ground control points, and how many?

To understand ground control points in aerial photography, you can envision your drone map floating over the real area it represents. In this metaphor, thin spikes poke through the map and into the ground at precisely measured points along the Earth—points with known X, Y (horizontal axis) and Z (vertical axis) coordinates.

In cases where the aerial survey data is not corrected by real-time kinematic (RTK) or post-process kinematic (PPK) methods, GCPs need to exist at frequent intervals around your surveying area so that the map result is more accurate than standalone GPS-grade accuracy (a few meters).

Another case where you would need so many GCPs is if the drone data should be aligned with existing terrestrial measurements or with a custom coordinate system where no accurate transformation is available.

Ground control points mark an exact point on Earth. They can be placed on an already-known point, or to establish the most accurate location, receiver will log its location according to the GCP center for several hours or a few minutes in RTK mode.

To better understand point distribution, imagine a table that requires weight on the top to be balanced. It will tip if the weights are not balanced across it, and it will be weak if they are too far apart. Evenly-distributed GCPs give you a strong model. The bigger and more complicated the area, the more GCPs needed.

For larger surveys, this can be labor intensive—not only to place the points accurately, but also to make sure nothing happens to them over the survey period. Hence the boom in RTK and PPK drone payloads. When you are flying with RTK or PPK-equipped drones, you don’t need so many GCPs. In fact, if your equipment is reliable, you may not need any, which we’ll get to later.

GCPs serve as an added layer of security, ensuring that your mapping outputs align with actual Earth-centric coordinates.

It’s important to note that GCPs are an integral part of post-processing the outputs, and the map results will be adjusted to fit the real-ground points you’ve placed, captured and “told” the software to honor. In fact, GCPs need to be the almighty truth in terms of accuracy, because they are a limiting factor, and a map can even be stretched to obey their placement. Let’s look at how to make sure they are as close to reality as possible.

The key difference between GCPs and checkpoints

The difference between GCPs (left) and checkpoints (right) emerges in the processing phase of your drone data. If you assign map location points as GCPs, the software will tether and even move these map points to be in line with the known points on Earth that they represent. Checkpoints, on the other hand, are drone data location points that you compare with known points to check your accuracy compared to what’s been validated on Earth.

What are ground control points in photogrammetry?

• Ground control points (GCPs) are places on the ground that have a precise known location associated with them.
• In photogrammetry, they are used to tie the map down to the Earth—matching the drone location data to the location data measured terrestrially.
• In case of a difference between the location accuracy of the drone data and the terrestrial data, the aerial map will be stretched during post-processing to tie down to the GCP.
• It’s important to note that GCPs are not the same as checkpoints, which are used in post-processing to validate accuracy by checking the map against the known points on Earth as captured during the survey.

Ground control points for drone mapping—best practices

Actual ground control points for drone mapping are ideally durable pieces of material that average a square foot (30 cm2) in size and feature a clear color pattern that displays their exact centers in aerial survey photos. They have a matte finish to prevent glare and are marked with high-contrast colors, such as white and black, yellow and black, or bright green and pink. The center of these squares are aligned to an exact point on the ground that is known because it has been measured by survey equipment calibrated precisely to that location on Earth.

What’s the difference among ground markers?

Square tiles like the one on the left work best. The other examples do not. Why? Let’s say you have a 3 cm (1.2 in) target area in the middle of your  X GCP configuration or even more in the circle painted around the geodetic point. This introduces enough space to produce a selection error, especially if your resolution is higher than 3 cm (1.2 in) per pixel. In Pix4D reports, this is called a “projection error,” which estimates how well the person processing the data selected the precise GCP point over multiple images containing it. It should be no more than one pixel. This error is factored into the final mapping accuracy.

Some surveyors may prefer to spray paint lines on the ground since they return to the site often and need more permanent ground control. It is recommended that rather than an X pattern, an L pattern be used in this case in order to mark the exact point. At times a landmark might be tempting to use as a GCP, say a corner of a building or top of a man-hole cover. Yet shadows and lack of contrast can make these points very difficult to locate the exact point needed. In any case, you will need to make sure that the point on your physical GCP is as clear as your minimum image resolution.

The above (Pix4D) processing image is from drone data covering a densely vegetated island. It helps us see that the key time to decide about GCPs is after processing step 1 in the photogrammetry report. At this point, you can see the tie point strength, with difficult areas shown as lighter colors and strong matching indicated by black. You can place GCPs in the lighter areas to strengthen your results. Like pounding a nail into the weak area to make it more sturdy.

The importance of these points being precisely placed, immobile and clearly marked cannot be overstated, because when it comes time to process location points in the aerial data, the resultant map will be aligned to these. Your data might be very accurate in such a case, but if the GCP is not as precise, the map will be moved accordingly. This is different than in the case of checkpoints, which we get to in the next section.

To validate WingtraOne PPK’s high accuracy, Wingtra used a set of checkpoints from the Institute of Geodesy and Photogrammetry at ETH Zurich (Swiss Federal Institute of Technology). Results are available in the white paper linked at the end of this blog.

How to establish ground control points for photogrammetry surveys

• Determine your survey area and locate points around the outside, but not too close to the edge so that several images capture the same point.
• If you are not flying with a PPK or RTK payload, place ground control at frequent intervals throughout the mapping area, avoiding straight lines and covering the space evenly, making sure to place at all elevations.
• If you are flying with a PPK or RTK payload, you shouldn’t need more than 4-5 GCPs for a square mile (2 km2), just make sure you place them to represent any fluctuations in terrain if that applies, i.e., up high and lower.
• Make sure each GCP is on a flat surface, is heavy so that it doesn’t move (painting on the ground suffices) and is matte finish with a clear corner or center as the point.
• Use a suitable terrestrial surveying method to measure each point with at least the accuracy that you want to assess (e.g., GNSS rover in RTK mode, static GNSS measurements or tachymeter measurements).

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When are checkpoints enough?

First, it benefits us to understand what a checkpoint is versus a GCP. In fact, the groundwork is the same: you need points on the Earth that are absolutely accurate according to terrestrial measurements, and you need them to be clearly represented in your aerial photographs.

The difference emerges in the post processing, because checkpoints are only used to double check the accuracy that you captured with the corrected drone data against the measurements on the ground.

Keep in mind that since both of these rely on physical points on the ground, checkpoints can be converted to GCPs during post processing if needed.

Differences between GCPs and checkpoints

Key points	GCP	Checkpoint
Requires clear markings on the ground to be visible in photographs
Must be verified accuracy
Precise midpoint must be as small as the mimium image resolution to be effective
Used by photogrammetry software during map creation and will influence mapping result
Used after map creation to compare accuracy of points on the map to known points on the ground–does not influence mapping result

In essence, checkpoint accuracy does not determine how the map is processed, it only serves as a verification step that the accuracy you collected with the drone is precisely close to that measured on the Earth for that exact point.

Did you know?

WingtraOne, which carries a high-end PPK payload, performs so well over multiple surveys that some customers—for specific high-contrast jobs like city mapping and mine pit mapping—only use checkpoints to verify accuracy.

The benefit of this is that your map is based on the accuracy that the drone picked up, and if it’s a reliable, high-accuracy drone, you won’t be introducing terrestrial measurements from GCPs. Why would you not want to introduce these? Because they could be prone to human error based on all of the factors listed above—namely good distribution and precise centerpoints. This could also be the case for checkpoints; however, your map won’t be processed according to them, only checked.

Along these lines, to get unbiased accuracy estimates to prove results to a client, you’ll want to include a few checkpoints in projects in projects that are processed with GCPs. Why? If you use only GCPs, your accuracy estimate is limited (and biased) since the map is optimized to fit the ground points vs. comparing the survey results to the ground points as a proof of accuracy.

The verdict

If you need high-accuracy photogrammetry outputs and do not have a PPK or RTK-equipped drone to capture better than GPS-level accuracy, you will need to place points, precisely and evenly, around your survey area. And you will need to treat these points as GCPs during processing to pin the map results down to Earth and get sub-inch/cm-level results.

Whether the drone is equipped with a PPK/RTK payload or not, the project will determine where and how frequently the points need to be placed, and in the case of PPK and RTK, whether those points will be more useful as GCPs or checkpoints. With PPK and RTK drones, less points overall are needed, so long as complicated areas—i.e., forested, grassy and undulating terrain—are well marked.

In cases of high-contrast urban or industrial projects like city maps or mines, PPK and RTK-equipped drones can provide accurate enough data so that you can use just three targeted, known locations as checkpoints. For corridors with vegetation or areas of difficult terrain within a map, you’ll need the points placed in these zones to serve as GCPs so you can nail down such areas. The good news is that with PPK and RTK-equipped drones you’ll need less of them.

In the end, it’s up to the pilot to determine when to treat points as GCPs or checkpoints, where to place them and how many are needed. This boils down to the type of project and the quality of the drone data collected over multiple projects, which helps an operator gauge a level or risk and whether or not that risk is too high.

Source: https://wingtra.com/ground-control-points-how-many-do-you-need-and-when-are-checkpoints-enough/

Internet of Fields: Drones & variable rate application

The Internet of Things has arrived in agriculture. Drone maps are the ideal tool to create variable rate application maps.

Tailoring the amount of fertilizer on crops is good for plants, good for the planet, and good for profit margins.

For variable rate fertilization to be most effective, farmers need an overview of their fields. That’s why more and more farmers use drones and precision agriculture for creating prescription maps.

A map created with a drone and a multispectral camera which will be used to create a targeted prescription for the field

 

 

 

 

Use case: Variable rate nitrogen fertilization in Germany

Nitrogen is the most used fertilizer input worldwide and a key component of chlorophyll, without which plants simply can’t thrive. Yet farmers throughout Germany are striving to reduce their use of the compound in alignment with environmental goals.

To get the plants the nutrients they need while reducing overall use of nitrogen, farmers are turning to precision agriculture: drone mapping and prescription maps for variable rate fertilizer application.

 

The benefits of variable rate fertilizer application

 

Variable-rate fertilization offers considerable advantages over the more traditional “blanket” applications.

• Variable-rate application (VRA) meets the needs of individual plants by delivering as much nutrition as they need – and no more.
• VRA prevents over-fertilization, which in the short term can burn roots and actually stunt growth. In the long time, over-fertilization can speed up soil acidification, affecting growth in the seasons to come.
• VRA reduces nutrient runoff, protecting streams and waterways.
• Applying only as much fertilizer as the plant needs means using less over all – which can be a significant cost saving.

 

 

Drone mapping for VRA

Soil, weather, and crop variety all affect plant growth, but the variable rate fertilization doesn’t change.

The first step is drone mapping. The advantages of drone mapping in precision agriculture are varied, but include:

• Drones can be used even in cloudy weather.
• Regular field overviews allow a faster response to crop issues.
• Drones can be used in large or small fields.
• Drone maps allow exact planning of fertilizer quantities.
• Field-specific application helps farmers to increase yields.

Drones are one tool among many, but for the next generation of farmers, they will become ubiquitous.

Use case: Field-specific growth regulator and pesticide applications

Understanding and mapping in-field variability is critical ahead of each fertilization application.

When growing rapeseed, variable-rate application of nitrogen in spring is key. Weather is never the same year to year, and because of this, fields often develop very differently, resulting in un-uniform harvests that translate into unpredictable profits.

Similar issues apply to cereal and vegetable crops, and the ability to map and generate variable rate application maps right before the fertilization is key to more predictable and uniform harvest.

Fertilizing the right amount at the right time can yield more uniform harvests

Seeing the invisible with multispectral cameras

Multispectral cameras like the Parrot Sequoia+ or MicaSense RedEdge help to make the invisible visible. These cameras integrate with specialized agriculture software which converts the information into meaningful data.

When it comes to crops, we know the importance of “boots-on-the-ground” so we developed Pix4Dfields to bridge the gap between the visible and the invisible – helping deliver further data to your existing workflows.

 

A precision agricultural toolbox

A new way of working makes new tools necessary. Each farm is different, but these tools will work in the majority of cases.

Drone	Choose a fixed wing drone such as the senseFly eBee for very large farms. For smaller farms, a rotary drone will work well.
Software	Pix4Dcapture for planning drone flights Pix4Dfields for processing and analyzing
Service provider	Working with a service provider like Agrarpohl can take the guesswork out of creating prescriptions.
Smart tractor or other dispenser	Smart tractors make it easy to apply the prescription to your fields.

 

Depending on the chlorophyll content and amount of biomass, plant population reflects light to varying degrees. The sensor on the drone measures the reflected light, and Pix4Dfields converts that information into maps that represent different growth stages.

Now you see it: index map (left) overlaid with a prescription map (right)

High NDVI (Normalized Difference Vegetation Index) values mean a high concentration of biomass. The amount of growth regulator such as fertilizer must then be increased because the leaf area is larger and vice-versa.

Many years of Agrarpohl’s own tests and trial plots have confirmed the total application rate reduction when using preparations variably, while at the same time benefiting from yield increases. Over the years, they earned 40 euros/ha more with the variable application of growth regulators.

Use case: Mapping the optimal harvest time for silage maize

It’s an issue as old as agriculture: when is the best time to harvest? Too soon or too late means taste and nutrients are lost – as are profits.

In this map, green means go

To determine the optimal harvest time for silage maize, Agrarpohl relies on drones and Pix4Dfields. Agrarpohl has created a custom index to measure the ripening of plants in a corn field (for silage), where optimal moisture level is between 60-70% moisture (30-40% dry matter). Corn harvested below 30% usually has too little starch in the corn. If it exceeds 35%, higher losses can occur during storage.

With traditional dry matter monitoring, the dry matter content of randomly selected plants per field was analyzed and then extrapolated for the entire field. This resulted in large variability.

Due to soil differences, for example, the plants often ripen faster in areas with low water retention capacity than in better areas.

In Pix4Dfields, the spatial resolution is extremely accurate. This allows the precise evaluation of individual fields or only parts of them. Plus:

• Targeted dry matter sampling from any part of the field
• Variety independent – works with any crop
• Determine and optimize harvest sequence and logistics
• Quality assurance of the optimal harvest date

Use case: Using drone mapping for crop insurance

Drones in agriculture are used for more than just VBA. They are also used for insurance. In the Midwest United States large rain events are common in the summer, saturating and then flooding the ground. Drainage is important in Iowa but it is often not sufficient for larger rain storms.

When damage occurs, farmers (policyholders) need to file a written notice of damage to be eligible for coverage. The written notice of damage or loss usually needs to be filed within 72 hours and initiates a claim procedure. This is what ultimately decides if the farmer gets paid or not.

Once in the field, the loss adjuster can take ground images and annotate them for the purpose of extra information and context

Typically, after an insurable event such as a flood, infestation or storm, inspection is carried out manually. First damaged areas are identified, then manually measured with such as a measuring wheel or tape to estimate the total area impacted and to calculate economic impact.

A third-party loss adjuster will fly a drone over the damaged areas and collect the data. The data can be processed in software such as Pix4Dfields to create a set of visuals based on which they can then assess the damage and create a PDF report for the farmer with the findings.

By using drones for insurance, farmers can get verifiable proof they can use for their compensation. And on the other hand, insurance companies positively stand out in the industry as the main stakeholders in helping farmers recover and stay in business after a disaster.

Source: https://www.pix4d.com/blog/drones-variable-rate-application#vra-de