Airborne Volcanic Object Imaging Detector

The Airborne Volcanic Object Imaging Detector (AVOID) is an advanced airborne sensing system developed to detect and image volcanic ash clouds in the atmosphere, especially those that pose threats to aviation safety. The system provides real-time detection of volcanic ash ahead of an aircraft’s flight path, allowing pilots to avoid dangerous airspace and thereby preventing engine damage or operational hazards.

Background and Development

Volcanic ash poses a serious hazard to aircraft because it consists of fine, abrasive, silica-rich particles that can damage jet engines, clog filters, and reduce visibility. The 2010 Eyjafjallajökull volcanic eruption in Iceland, which disrupted air traffic across Europe for several days, exposed the lack of in-flight ash detection capabilities and prompted renewed efforts to develop airborne sensors.
The AVOID system was developed through collaboration between Airbus, easyJet, and the Norwegian Institute for Air Research (NILU). Its design aimed to create a forward-looking, on-board instrument capable of detecting volcanic ash clouds in real time, up to 50–100 kilometres ahead of the aircraft, enabling pilots to take timely evasive action.

Design and Principle of Operation

The AVOID operates using dual-wavelength infrared (IR) cameras mounted externally on the aircraft. These sensors detect the characteristic spectral signatures of volcanic ash by analysing the emitted and reflected infrared radiation in the 8–12 micrometre (µm) range, where silicate ash particles exhibit distinct absorption features.
Key features of the system include:

• Infrared imaging technology that differentiates volcanic ash from meteorological clouds (water or ice).
• Forward-looking geometry, which enables monitoring of the airspace directly ahead of the aircraft at cruising altitudes between 10 and 16 kilometres.
• Automated data processing algorithms that identify ash concentrations based on their thermal radiation patterns.
• Real-time display to inform pilots and ground control centres about detected ash layers and their distance from the aircraft.

By utilising the differences in spectral radiance between ash clouds and meteorological clouds, the AVOID can generate visual and numerical data to locate and quantify the extent of volcanic ash.

Testing and Validation

The system underwent extensive testing between 2011 and 2013 in collaboration with European research agencies and aviation manufacturers.

• Initial field trials were conducted over Mount Etna and Stromboli (Italy), demonstrating the system’s ability to detect ash layers under controlled conditions.
• In 2012, Airbus equipped an A340 test aircraft with the AVOID system and successfully detected ash layers at distances exceeding 60 kilometres.
• A major field validation experiment was carried out in 2013 over the Bay of Biscay, where a controlled release of 1000 kilograms of volcanic ash simulated natural conditions. The AVOID successfully identified and tracked the artificial ash cloud at a range of about 67 kilometres, confirming its sensitivity to concentrations as low as 200 micrograms per cubic metre (µg/m³).

These trials demonstrated the AVOID’s operational viability and led to further research into integration with commercial airliners.

Applications and Significance

The AVOID system’s principal application lies in aviation safety. During volcanic events, pilots often rely on satellite data and advisory charts from the Volcanic Ash Advisory Centres (VAACs), which may not provide real-time, localised information. AVOID fills this gap by offering on-board, immediate detection.
Main benefits include:

• Real-time hazard awareness: Provides immediate alerts to pilots of volcanic ash ahead of the aircraft.
• Operational flexibility: Allows aircraft to reroute or adjust altitude to avoid ash, minimising disruptions.
• Enhanced flight safety: Reduces the risk of engine damage, sensor blockage, and loss of thrust due to ash ingestion.
• Complementary system: Supports satellite and ground-based detection systems for comprehensive airspace monitoring.

Airlines such as easyJet have shown interest in integrating AVOID systems into their fleets, especially for routes near active volcanic regions such as Iceland, Indonesia, and Japan.

Advantages and Technical Strengths

• Long detection range of up to 100 kilometres at typical cruising altitudes.
• Non-invasive technology, requiring minimal modifications to aircraft design when mounted externally.
• Infrared spectral analysis capable of differentiating volcanic ash from ice or water clouds.
• High sensitivity to low ash concentrations, aligning with safe exposure limits defined by international aviation authorities.
• Potential integration with flight management systems for automated hazard avoidance.

Limitations and Challenges

Despite its advantages, the AVOID system faces certain technical and operational limitations:

• Detection limits: Extremely low ash concentrations or very thin ash layers may go undetected.
• Environmental interference: High background infrared radiation or mixed atmospheric conditions can affect accuracy.
• Calibration and maintenance: Regular calibration is required to maintain sensitivity, especially under varied flight conditions.
• Certification and cost: Integrating such advanced sensors into commercial fleets requires regulatory approval and significant investment.

Additionally, while AVOID can identify volcanic ash, distinguishing it from desert dust or industrial aerosols remains challenging due to similar spectral characteristics.

Broader Implications for Aviation Safety

The AVOID represents a significant technological advancement in in-flight hazard detection. Its successful integration into commercial aviation could prevent incidents similar to those during the Eyjafjallajökull eruption and reduce unnecessary flight cancellations by improving real-time situational awareness.
The system aligns with global efforts by organisations such as the International Civil Aviation Organization (ICAO) and European Aviation Safety Agency (EASA) to enhance volcanic ash monitoring and response systems.

Future Prospects

Ongoing developments aim to improve the sensitivity, automation, and integration of AVOID technology. Future versions are expected to:

• Use machine learning algorithms for more accurate discrimination between ash and other aerosols.
• Be incorporated into next-generation aircraft as part of comprehensive environmental hazard detection suites.
• Share real-time data with ground networks and air traffic control for coordinated responses.