Scared to enter the sewer? Roll in the caged drone!

Swiss drone manufacturer Flyability surely knows a thing or two about drones in hostile environments.

From their inaugural GimBall – which rolled away from the 2015 Drones for Good in Dubai $1million richer – to the latest Elios series of drones specifically designed for claustrophobic surfaces, the company has perfected the art of making caged drones that will survive tunnels, shafts, roofs and other places too dangerous for humans to venture into.

“We build solutions for the inspection and exploration of indoor, inaccessible, and confined spaces,” Flyability say on their website. “By allowing drones to be used safely inside buildings, it enables industrial companies and inspection professionals to reduce downtime, inspection costs, and risks to workers. With hundreds of customers in over 50 countries in Power Generation, Oil & Gas, Chemicals, Maritime, Infrastructures & Utilities, and Public Safety, we have pioneered and continue to lead the innovation in the commercial indoor drone space.”

Traditionally, sewer inspectors rely on three different methods for conducting visual inspections. These methods are:

  • Manned entry
  • Raft or sled-mounted remote inspection, typically using CCTV cameras
  • Robotic inspection, using Central Circuit Television (CCTV) cameras and/or other types of sensors (LiDAR, SONAR, and others)

However, although it can help inspectors collect detailed data on the condition of the asset, manned entry presents inspectors with a host of safety concerns. Besides, it is also impossible to physically inspect certain areas, due either to access issues or to the inability to get temporary bypass of flows.

CCTV on a raft or sled is one of the most common methods sewer inspectors use to collect visual data remotely. But once the camera is in the water there is no way to control where it’s pointed or how fast it moves through the system, and this lack of control leads to unreliable data capture.

Robotic solutions with multi-sensor platforms (CCTV, SONAR, laser profiling, or LiDAR) can yield a huge amount of data, but are often very expensive. And their size can present significant issues with access—most robots used in sewer inspections are so big they need to be lowered into the sewer system with a small crane.

Small, stable, and easy to control even in high flow conditions, a drone like the Elios 2 can enter a sewer system and collect high quality visual data without any advance preparation, and at a relatively low cost.

With a few years under their belt for indoor drone inspections, we thought the following list of the benefits of using drone technology to inspect dangerously high, low and dark places should be heeded.

Here is Flyabiility’s top eight reasons why you should use a drone for sewer inspections.

Savings on costs

Drones help make sewer inspections more efficient by removing the need for inspectors to physically enter sewer systems, thereby eliminating extra personnel costs and helping cities realize significant savings.

Péter Kövessi, former Director of Client Services at Flind—a company that helps oversee the massive sewer infrastructure in the city of Barcelona—estimates that sewer inspections conducted by drone are twice as efficient as human inspections and 40 percent less expensive per meter of inspection.

Drones also have the potential to eliminate the need for using expensive robotics alternatives, which can help inspectors realise even more savings.

Indoor inspections should be safe


The type of confined space entry required for sewer inspections always presents a certain level of risk to inspectors.

In addition, sewers present specific safety hazards to inspectors in the form of rushing water and the potential presence of noxious gases, such as Hydrogen Sulfide (H2S). In some cases, sewer inspectors must use scuba gear outfitted with PPE to protect them from the presence of raw sewage in order to conduct their inspections.

Using an indoor drone to collect visual data can reduce or even eliminate the need for inspectors to enter a sewer system, vastly improving safety for the inspection process.

Data Localisation

Another drawback to using CCTV or robotics solutions for collecting data within sewer systems is that it can be hard to pinpoint the exact location of a defect identified by these methods—inspectors may see something that needs to be fixed, but they can’t always tell where it is in the asset.

But identifying a defect is only half the job of an inspection.

Inspectors also need to be able to tell their clients where defects are located in a way that can be shared with others, so that the defect can be evaluated and maintenance can be performed quickly and efficiently.

Flyability has inspection software like the Inspector 3.0, which allows inspectors to pinpoint the location of defects identified during inspection flights.

This data comes in the form of sparse point clouds that provide accurate, detailed data about the locations of defects found during a mission. These point clouds have precise data, allowing inspectors to measure the size of the defects and pinpoint where further investigation or attention is required.


Manned entry is just not feasible in some sewer inspection scenarios due to access requirements or to the need to temporarily bypass flows, which could be cost prohibitive or simply impossible (as in large diameter or trunk sewers).

Robotics solutions also can’t enter some sewer inspection systems due to size limitations.

But a drone made for the purpose can access sections of sewer systems through manholes and other small entry points, allowing inspectors to collect stable, high quality visual data regardless of access issues.

Extended Range

The RVI techniques mentioned above, like floating a CCTV or other type of camera from one manhole to another, can present range limitations, which can limit their usefulness in certain inspection scenarios.

Flyability’s Range Extender allows its indoor drones to fly farther from the pilot in order to perform inspections with greater efficiency.

Light in the tunnel…

High Quality Visual Data

The quality of the images and video that can be captured using a drone is much higher than what can be captured using CCTV or other more expensive robotics solutions.

Inspectors working in sewer systems have reported using the Elios 2 to capture crystal clear media of a quality they’ve never been able to achieve before.

A few other elements that contribute to the high quality of the drone’s images and videos are:

  • Lighting. The Elios 2 carries 10,000 lumens of light, enough for it to light up a dark sewer system so that inspectors can see every part of it.
  • Camera control. Inspectors can control the speed and angle of the camera, allowing them to capture exactly what they need for inspection purposes.
  • Drone control. Inspectors can hover in one location, or fly back in order to investigate a defect further, allowing them to capture as much clear, high quality video footage of an area as they need.
  • Lighting control. Lighting can be shifted to provide an oblique light source that reveals pitting and depth, similar to the effect of an inspector moving a flashlight around the surface of an object.

Stability — Even in High Flows

Drones like the Elios 2 are small and easy to deploy for sewer inspections, but they’re also very stable in flight. The Elios 2 has been used in a system where the water was roaring through at an average velocity of 26 feet per second — a speed so fast that the power of the water generated airflow in the space between the water and the pipe that created turbulence for flying.

But despite the high rate of flow, the drone remained stable in flight, capturing images and video for inspectors that were so clear they were able to completely eliminate the need for an inspector to enter the sewer system.

Reduction of Emergency Response Time

Drones can help significantly reduce the amount of time it takes to identify the cause of a problem during a sewer emergency.

Flyability has a use case of Barcelona, where inspectors were faced with an urgent problem when a wastewater interceptor that served five different municipalities suddenly broke during a severe storm.

Every moment counted in this emergency, since the damaged pipe was leaking raw sewage into the sea at a rate of 500 cubic meters per second. Although the broken pipe was ten feet in diameter, there was no way for inspectors to enter it because sewage was pouring out at such a rapid rate. Inspectors were able to fly the Elios into the pipe through intact manholes, both upstream and downstream of the visible break, and quickly survey the entire area to identify the exact location of the break and extent of the damage. Using this information, experts on the scene were able to ensure that the bypass was connected at the correct place to quickly stop the flow of waste into the sea and to avoid the risk of a future break.

Source: Flyability


Leave a Comment


Welcome! Login in to your account

Remember me Lost your password?

Lost Password