We have tried to answer the most commonly asked questions on this page however if your query isn’t answered here please don’t hesitate to call us on 01444 401840 or drop us an email at info@raaltd.co.uk and we will be happy to answer any other questions you might have.


Can you explain what UAV, RPAS, GIS and other terms I have heard mean?

Yes – click here for our full glossary of UAV and survey related terms

How accurate are your surveys?

Clients who haven’t used a UAV before are often concerned about the level of accuracy that can be achieved, we can assure you that UAVs can offer the most spatially accurate aerial survey data currently available. To find out why this is you can read our article here The error of our extracted survey points can get down to around 9mm in height and 6mm in plan with good ground control, and specialised post-processing techniques. For most land surveys we generally work to around 40mm in height and 30mm in plan. The cost of these surveys per unit area does vary and so the higher accuracy you require the more it will cost. It is therefore a good idea to understand what you are trying to achieve and the tolerances you need to achieve it.

Can your topographic surveys provide terrain data under vegetation?

Yes, our LiDAR unit is able to penetrate the tree canopy

What is photogrammetry? 

Photogrammetry is the science of making precise measurements from photographs. We are able produce photographs at a far higher resolution than can typically be achieved with traditional aircraft based aerial surveys and from these produce a variety of data products including 3D building models. The result is similar to that produced by laser scans but at a fraction of the cost. Find out more about photogrammetry

Are you able to survey below ground level features such as drains and man holes?

Yes, we have lots of experience doing this. Please let us know the features you would like included in the survey

What are your flight times?

A typical flight with our DJI Matrice 210 platform lasts between 15 and 25 minutes. However, these times vary depending on a variety of factors including the weather, flight characteristics and the camera system being carried. For example, a slow, low-level flight with the Skyjib 6 or 8 carrying our lightest camera (the Optris PI thermal camera) would have a significantly longer flight time than when the UAV is carrying our heaviest camera (the Canon 5D MK III) in high winds and at high speeds.

Although these flight times may not seem like very much, in our experience they are easily long enough to enable us to achieve a great deal. We also carry with us a number of batteries which can be swapped over quickly enough in order to proceed with the flight almost immediately. Furthermore, we have on-site charging capabilities allowing us to always have enough batteries to be able to begin another flight.

What weather conditions can you fly in?

Generally speaking we can fly in weather conditions with winds up to 17mph and no more than very light rain (although our Skyjib 8 cannot fly in the rain at all due to its exposed electronics). This is due to the potential damage that this could do to the kit and the negative impact it could have on the quality of the photo. If there are adverse weather visibility conditions (e.g. fog/haze) we may need to alter our flight plan in order to maintain a line of sight with the UAV.

What is the maximum distance and height you can fly to?

As ruled by the CAA, we are permitted to fly at heights of up to 400ft above ground level (approximately 120m), and at distances of 500m from the pilot. This is in order to ensure the UAV stays in the pilot’s line of sight. We monitor the UAV’s altitude and distance from the pilot using telemetry information fed back to the pilot’s screen. This also streams to the pilot live video footage from the UAV, known as a first person view camera, which aids long distance navigation.

Are you able to operate in congested areas, such as central London?

Yes this is possible. Sometimes extra permissions need to be sought when operating in central London. The cost of the survey can increase if it is in a complex area since most of the City of London is a resricted area and any aircraft, no matter how small has to submit a non-standard flight application to fly in these areas. This can take up to 21 days and permission is not guaranteed. Since London is a congested area this can limit the size of aircraft that can fly. As a result working in London is possible but it is essential to allow at least a month to organise the project.

Is there anywhere you can’t fly?

Unfortunately, yes. As well as the constraints set out by the CAA to protect public privacy, there are certain airspaces across the country where we need permission from the relevant Air Traffic Control to fly. These areas are typically around airports and sites of military activity. We also need permission from the landowner for land we want to take-off or land on. For more information on the factors affecting where we can and cannot fly, please see our article

Can you fly indoors?

Yes, we’re perfectly able to fly indoors.

What weight can it carry?

Our larger platforms – the Skyjib 6 and 8 – can carry loads of up to 10kg, whilst the DJI Phantom can only carry a GoPro camera (approximately 74g).

How fast can it fly?

The maximum speed of the Skyjib 8 and DJI Phantom is 20mph, and the Skyjib 6 is 30mph.

What fuel do the UAVs use?

All of our UAVs use two Lithium Polymer (LiPo) batteries.

How much do your services cost?

Due to how much our work tends to vary in terms of timescale and data processing requirements, it is very difficult to quote a standard price for our jobs but we are always happy to offer a free no obligation quote. We are usually able to give you a rough estimate of costs in a quick phone call.

Please contact us to discuss your aerial surveying needs and we will supply you with a bespoke estimated quote for our services.


Are you insured?

Yes – all our machines, cameras and data are insured and we have £5 million public liability insurance.

Are you legally allowed to do this?

We have a “Permission for Commercial Operations” (PfCO) from the Civil Aviation Authority (CAA) which regulates aviation activity in the United Kingdom. This allows us to operate our UAVs commercially and perform aerial data acquisition. Furthermore, we always operate well within applicable legislation, including CAA regulations and the Data Protection Act. For more information on legal stipulations surrounding the use of UAVs, please see the CAA’s guidance at www.caa.co.uk/Consumers/Unmanned-aircraft-and-drones/ 

What qualifications and training do your pilots have?

All of our pilots possess Remote Pilot Qualifications for multirotor platforms (RPQ-s). These qualifications have been granted to them by a CAA approved pilot assessment body. This qualification assesses the pilot’s competence regarding the knowledge necessary to become a commercial UAV pilot, including knowledge of aviation law, meteorological conditions and human factors which affect flight safety. To pass this they must also have passed a practical and UAV-specific annual flight assessment. In addition to this, all of the pilots have undergone systems training with the manufacturer and receive ongoing in-house training. For full information on this, please see our article

What emergency prevention features do your UAVs have?

As well as our numerous procedures which reduce the likelihood of an accident, our systems all possess in-built emergency prevention features to minimise any damage in the unlikely event of an emergency. This includes low battery voltage alarms, motor redundancy (the Skyjib 6 can still fly in the event of one motor failing and the Skyjib 8 can fly with two motor failures) and a return to home feature which, if contact with the radio controller is lost, allows the UAV to fly back to its take-off zone at a pre-defined height and land itself.


How do you ensure the privacy of the public and third parties?

As we carry imaging equipment on our UAVs we must adhere to a number of regulations set out by the CAA to protect the privacy of the public and third parties. This includes flying the UAV no closer than 150m to congested areas and organised open-air assemblies of 1,000 persons or more. We must also fly no closer than 50m to any structure, vehicle or person without their permission, although we may fly above them at altitudes of over 50m. The exception to this is that we may fly as close as 30m to persons without their permission during take-off and landing. Please see our infographic on for an illustration of what this means.  We also comply with the Data Protection Act and we work with the client to ensure that this is complied with at all stages of the work. UAVs are covered by the Data Protection Act and as such, all privacy laws can be applied to their use. For more information visit https://ico.org.uk/for-the-public/drones/

Glossary of Terms

Popular Terms within the UAV industry


Civil Aviation Authority; the UK’s aviation regulator


An increasingly popular term for UAVs often used in a military context.

Flight Commander

The member of the flight team who is responsible for directing the flight and operating the camera equipment


A gimbal is the mount where the camera sits enabling it to move along multiple axes and be positioned with a remote control.


LiPo stands for Lithium Polymer and is the type of battery used by the majority of drone manufacturers as it is lightweight with good charge capacity and power.


Permission for Commercial Operations


This is the up and down movement of the UAV on a vertical axis, encompassing from the front to the back of the UAV.


This is the rotation of the UAV from nose to its tail including all movements forwards, backwards and left to right along the horizontal axis. To prevent crashing the yaw, pitch and roll of a UAV needs to be kept as stable as possible.


Remotely Piloted Aerial System; one of the newer terms used to define UAV systems


Remote Pilot Qualification; the qualification awarded to pilots upon successful completion of the UAV training course with Resource UAS


Unmanned Aerial System; introduced to improve on the term ‘UAV’ as it is inclusive of all the components which contribute to the flight


Unmanned Aerial Vehicle; considered by some to be a legacy term


Yaw is the rotation of a UAV in relation to the centre axis. Looking down on a drone from above, the yaw would be the movement of the drone, clockwise/anti-clockwise.

Popular Terms within the Survey & Mapping Industry


Digital Elevation Model – most of the time used as a generic term for DSMs and DTM but is essentially a ‘bare earth’ elevation model, unmodified from its original data source (such as lidar, ifsar, or an autocorrelated photogrammetric surface)


Digital Surface Model is a DEM of the earth surface including objects on it such as buildings and trees so it will include the tops of buildings, trees, powerlines, and any other objects – it only ‘sees’ ground where there is nothing else overtop of it.


Digital Terrain Model is a DEM of the earth surface without any objects in it


A GIS is a computer based tool or information system that enables the capture, processing, organisation, analysis and presentation of geographic data i.e. mapping and organising data. The system generally comprises the software, hardware and applications required for these tasks along with the necessary data.


Light detection and ranging -Usually by using airborne laser scan technology (LIDAR), the surface of the earth can be scanned to generate a DSM with accuracies down to the centimetre range. This technique involves shooting a laser beam from an aerial platform and measuring the time it takes to reflect back to the sensor.


An orthophoto is created from images using photogrammetric procedures and provides distortion-free, true-to-scale images of the surface of the earth.


Photogrammetry is a technique which uses photography to extract measurements of the environment. This is achieved through the use of overlapping imagery; where the same feature can be seen from two perspectives it is possible to calculate measurements.

Remote Sensing

Remote sensing is the process of making measurements of the earth using sensors on UAVs or other platforms. These sensors collect data in the form of images and have the capability for manipulating, analysing, and visualising those images. Remote sensed imagery is then integrated within a GIS.

SAR (Synthetic Apeture Radar)

Similarly to LiDAR, SAR measures the time taken for a pulse of radar to return to the sensor after reflecting off the earth’s surface.

Spatial Analysis

Spatial analysis is a set of techniques for analysing spatial data. It is the process of examining the locations, attributes, and relationships of features in spatial data through overlay and other analytical techniques. Spatial analysis extracts or creates new information from spatial data.

Topographic Survey

Topographic Surveys are used to locate and map the contours of the ground and existing features on the surface of the earth or slightly above or below the earth’s surface (i.e. trees, buildings, streets, walkways, manholes, utility poles, retaining walls, etc.).