Meteorological Sensors for Aviation

Bristol Industrial & Research Associates Ltd (Biral) was established in 1975 and is a global supplier of meteorological sensors for aviation. Our scope extends from sensors to measure wind speed and direction, temperature, precipitation, solar radiation to visibility and present weather sensors.

Biral’s SWS and VPF range of visibility and present weather sensors are used throughout the world as part of aviation ground control and meteorological monitoring systems. These sensors along with the ambient light sensor form the core of RVR monitoring systems used to control the safe landing of aircraft in reduced visibility conditions. Our present weather sensors provide automated precipitation classification and monitoring that forms a vital part of the METAR signals broadcast to aircraft.

Transmissometers were once the reference sensor on airfields due to their direct measurement of extinction coefficient. However, their limited measurement range and high capital and operational costs has seen the more cost effective forward scatter meters (FSM’s) become widely used.

All Biral visibility and present weather sensors meet the requirements of ICAO and WMO for use in aviation systems including RVR. Calibration is in accordance with ICAO 9328 and is traceable to a reference standard transmissometer. Declarations of Suitability for Use as per EU Regulation 552/2004 on the interoperability of the European Air Traffic Management network are available for all sensors.

Smaller airfields without the need for RVR may cluster a set of sensors around a met-tower, whilst larger airports have sensors at both ends of a runway. The largest applications can have three sets of sensors per runway in addition to a dedicated set for meteorological observation and forecasting. The Biral sensor range is perfectly suited to the varying needs of all these installations.

Biral visibility and present weather sensors have a range of features that reduce maintenance to a minimum. All Biral sensors have simple to use field test and calibration kits, allowing the operator to maintain a high degree of confidence in the measurements without the disruption and expense of removal for offsite calibration.

The detection and reporting of thunderstorms is important in the aviation industry, supporting both the safety of ground operations and the provision of meteorological data to aircraft and forecasting authorities. Our Thunderstorm Detector has been developed to be compliant with FAA regulations for lightning detection systems used at airfields.

The BTD-300 Thunderstorm Detector is a standalone sensor that reliably detects the presence of all forms of lightning to a range of 83km. The distinctive quasi electrostatic operating principle gives the detector a very low false alarm rate and the ability to warn of the risk of overhead lightning, which network systems are not able to do.

To view our range of meteorological sensors for aviation visit

Company Profile

  • Visibility & Present Weather Sensors

    Biral forward scatter Present Weather Sensors measure visibility and report precipitation type and intensity. These compact sensors can identify a wide range of precipitation types including drizzle, rain, snow, hail, freezing rain and other forms of frozen precipitation.

    Precipitation type is reported using a combination of WMO Table 4680 and METAR codes. The range of precipitation types identified varies with sensor model.

    Advantages of Biral Forward Scatter Meters

    • Much more compact
    • Require little maintenance
    • Report visibilities from 10m to 75km
    • Performance proven to be comparable to that of transmissometers
    • Uses a unique back scatter receiver to improve classification accuracy
    • Reports the correct precipitation code reliably even in the most difficult conditions
  • Ambient Light Sensors

    The ALS-2 Ambient Light Sensor is designed to measure background luminance as part of a Runway Visual Range (RVR) system. Mounted alongside the runway the ambient light sensor is often deployed with a visibility meter to provide the data necessary for calculation of RVR.

    Designed to comply with specifications and guidelines produced by the International Civil Aviation Organisation (ICAO), World Meteorological Organisation (WMO) and the Federal Aviation Administration in the USA (FAA), the ALS-2 meets all the requirements for use in typical RVR systems.

    The ability to connect the sensor directly to a Biral visibility or present weather sensor and have the background luminance data incorporated into the visibility sensors data string simplifies system design and construction.

  • Thunderstorm Detectors

    The BTD-300 Thunderstorm Detector is a standalone sensor that reliably detects the presence of all forms of lightning to a range of 83 km. The unique quasi electrostatic operating principle gives the detector a very low false alarm rate and the ability to warn of the risk of overhead lightning.

    The ability to reliably detect and range cloud-to-cloud lightning, which is typically much more common than cloud-to-ground strikes, makes the BTD-300 much more sensitive to the presence of storms compared to devices that rely on radio detection. The electrostatic operating principle allows the sensor to warn of the risk of overhead lightning before the first discharge occurs.

    Virtually maintenance free in operation, the BTD-300 can either interface directly to an integrated system or be operated using the supplied PC compatible display and logging software. The optional warning relay module allows the sensor to automatically sound alarms whenever a storm approaches.

Company News

Biral and Microstep-MIS Gain Russian Certification for Meteorological Sensors 

Biral and Microstep-MIS are pleased to announce that on February 3 2021, the Russian office of MicroStep-MIS received the certificate of state registration of measuring instruments for visibility and present  weather sensors, issued by the …

Biral reflects on 2020 with team expansions and global projects

Meteorological experts Biral has reflected on 2020 as a challenging but productive year that saw the company announce a series of new products as a result of its forward research and development programme. In the …


This month sees the 45th anniversary of Biral, one of the World’s leading manufacturers of specialist meteorological instruments. Short for Bristol Industrial and Research Associates Ltd., Biral is engaged in continuous research and development in the …


Meteorological equipment specialist Biral has just launched a new, mobile friendly microsite for its new and sophisticated BTD-200 lightning warning system. The modern and simple design focuses entirely on the BTD-200 and is responsive …

Biral Sales Team Covers the Globe

With the majority of Biral’s meteorological sensors being exported, the international sales team covers the globe from its offices based in Bristol, UK. The team works with a wide range of applications and clients around …


Meteorological equipment specialist Biral has recently added to its in-house marketing team and last month appointed Amy Sear as its new Marketing and Communications Officer. Amy has joined Biral after spending almost nine years in the …


Meteorological equipment specialist Biral is expanding and has taken on an experienced International Sales Manager to add to its growing team. The company appointed Artur Miller last month as its International Sales Manager, where he is …


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