Landfills are among the most significant and least visible sources of methane emissions in the waste sector. Decomposing organic material beneath the surface generates landfill gas continuously, and even well-engineered cover systems develop cracks, settlement zones, and permeable patches that allow gas to escape. Detecting those escape points accurately and efficiently is a growing priority, especially as regulatory requirements tighten across Europe. Aerial leak detection offers a compelling solution, combining speed, sensitivity, and broad spatial coverage in a way that ground-based methods simply cannot match.
This article walks through how airborne methane surveys work on landfill covers, from the physics of the detection method to the final emission maps that operators use to meet their EU Methane Regulation obligations.
Why landfill covers are a unique methane challenge
Landfill covers present a fundamentally different inspection problem compared to buried pipelines or compressor stations. Rather than a single linear asset with defined leak points, a landfill cover is a large, irregular surface area, often spanning tens of hectares, where methane can seep through anywhere the barrier integrity is compromised. Settlement, root intrusion, freeze-thaw cycling, and degradation of geomembrane materials all create pathways for landfill gas to reach the atmosphere.
The challenge is compounded by the sheer scale of the task. Walking a large landfill cover with handheld detectors is time-consuming, physically demanding, and prone to gaps in coverage. Methane concentrations also vary with wind direction and atmospheric conditions, meaning a ground-level reading at one point in time may not reflect the true emission picture. For operators managing multiple landfill sites, a scalable and repeatable inspection method is essential. This is precisely where airborne methane surveys prove their value.
How the DIAL method scans a landfill from the air
Differential Absorption LIDAR, or DIAL, is the core technology behind effective airborne methane detection on landfill covers. The method exploits a fundamental property of methane molecules: they absorb light at specific wavelengths in the infrared spectrum. By emitting two laser pulses simultaneously, one tuned to a wavelength that methane absorbs strongly and one that it does not, the system can calculate the concentration of methane along the laser path with high precision.
In practice, a helicopter carrying the DIAL sensor flies systematic parallel transects over the landfill at low altitude, typically between 100 and 150 metres above the surface, at speeds of up to 180 km/h. The laser fires at a high repetition rate, generating a dense grid of measurement points across the entire cover area. Because the sensor integrates the methane column between the aircraft and the ground, it captures gas that has escaped the cover and is present in the air above it, regardless of whether that gas has already dispersed horizontally. The result is a spatially continuous picture of methane distribution across the landfill surface, far more complete than anything achievable by walking the site.
Minimum detectable leakage rates and wind conditions
Sensitivity is a critical factor when evaluating any methane detection method for landfill cover inspection. DIAL-based airborne systems can detect leakage rates as low as 150 litres per hour under operational conditions, which is sufficient to identify even relatively minor seepage through cover materials before it becomes a significant emission source.
Wind plays an important role in aerial methane surveys. On one hand, some wind is helpful because it creates a detectable plume above the emission point, which the airborne sensor can measure as it flies through the column of gas. On the other hand, very high wind speeds dilute the plume rapidly and can push it outside the measurement path before the aircraft passes overhead. DIAL surveys remain effective at wind speeds of up to approximately 24 km/h, which covers the majority of operational days at most European landfill sites throughout the year. Survey planning typically accounts for local meteorological conditions to ensure flights are conducted within the optimal wind window.
From raw data to actionable emission maps
Collecting millions of laser measurement points over a landfill cover is only the first step. The real value for landfill operators lies in how that raw data is processed and presented. After the flight, the measurement data is georeferenced and processed to produce spatial concentration maps that overlay directly onto satellite imagery or site plans of the landfill.
These maps show not just where methane is present, but also its relative concentration, allowing operators to prioritise repair and maintenance work on the highest-emission zones first. Site-level emission quantification is also possible, meaning the total methane flux from the landfill can be estimated from the survey data, a figure directly relevant to annual emissions reporting. Survey results are typically delivered through a secure Web GIS platform, accessible on both desktop and mobile devices, so site managers and compliance teams can review findings, annotate observations, and share data with third-party verifiers without cumbersome file transfers.
This structured output connects the field survey directly to the reporting and verification workflow that regulators increasingly expect.
How aerial surveys support EU Methane Regulation compliance
The EU Methane Regulation 2024/1787 sets out clear obligations for operators of methane-emitting facilities, including landfill sites that fall within its scope. Operators must conduct regular leak detection and repair programmes, quantify emissions at the source and site level, and submit those figures to independent third-party verifiers as part of annual reporting cycles.
Airborne LDAR surveys on landfill covers are well aligned with these requirements. A single helicopter survey can cover an entire landfill site in a matter of hours, producing georeferenced emission data that satisfies both the spatial and quantitative requirements of the regulation. The high sensitivity of DIAL technology means that even diffuse, low-rate seepage through cover materials is captured, reducing the risk of under-reporting emissions that could trigger regulatory scrutiny. For operators managing several landfill sites across a region, the speed of aerial surveys also makes it practical to inspect the full portfolio within a single compliance period rather than spreading inspections across multiple years.
As the 2026 compliance calendar brings the first full reporting cycles under the EU Methane Regulation into focus, operators who have already established a repeatable aerial survey programme are in a significantly stronger position than those still relying on manual inspection methods.
How ADLARES supports landfill methane monitoring
We provide end-to-end aerial methane detection for landfill operators who need reliable, regulation-grade emission data without the logistical burden of large-scale ground surveys. Our CHARM® DIAL technology, the world’s only DVGW-approved airborne gas remote detection system, delivers the sensitivity and spatial coverage that landfill cover inspection demands. Here is what working with us looks like in practice:
- Full-site aerial coverage in a single flight session, regardless of landfill size or surface complexity
- Detection of leakage rates from 150 l/h, capturing diffuse cover seepage as well as concentrated emission hotspots
- Site-level emission quantification that feeds directly into annual methane reporting under EU Methane Regulation requirements
- Georeferenced emission maps delivered via a secure Web GIS platform, ready for use by compliance teams and independent verifiers
- Rapid turnaround from flight to final report, supporting tight regulatory deadlines
Over 250,000 km of gas infrastructure has been inspected using our technology across Europe, and our experienced team brings that depth of operational knowledge to every landfill survey we conduct. If your site needs a credible, high-sensitivity methane survey that stands up to regulatory scrutiny, contact ADLARES to discuss your inspection requirements and find out how we can help you meet your 2026 compliance obligations.