Wind Sensor

A Wind Sensor is an electronic instrument that measures wind speed and direction with high accuracy, providing real-time data for air traffic control, weather reporting, and automated airfield systems. Unlike traditional mechanical wind cones or anemometers, electronic wind sensors offer precise numerical data that can be integrated into ATC displays, approach systems, and weather networks. Common technologies include: ultrasonic (using sound waves to measure wind speed and direction), cup-and-vane (a classic mechanical design with electronic readout), and hot-wire (using thermal dissipation to measure airflow). Wind sensors are typically mounted on masts or towers at a height of 6–10 metres, away from obstructions, to ensure accurate, undisturbed measurements. The data from wind sensors is critical for runway selection, approach procedures, and aircraft performance calculations.

Electronic wind sensors exist to give ATC, pilots, and automated airfield systems precise numerical wind data rather than the approximate visual read a windsock provides, which matters when a crosswind or gust is close to an aircraft's operating limits and a rough visual estimate isn't precise enough to base a safety decision on. Because the data can be fed directly into ATC displays and automated systems, it also supports faster, more consistent runway-selection and go/no-go decisions than would be possible from visual observation alone.

This precision becomes especially valuable during marginal conditions — gusting or rapidly shifting wind — where the difference between an acceptable and an unacceptable crosswind component may be only a few knots, and where a pilot or controller needs a trustworthy number rather than an impression to decide whether an approach or departure should proceed.

Installed at all major airports, military airbases, and many smaller airfields where precise wind data is required. Typically placed near the runway threshold, at the centre of the airfield, or at multiple locations for comprehensive wind coverage. Used for:

• Air Traffic Control – providing real-time wind data for takeoff and landing clearance
• Weather Reporting – feeding data into METAR, ATIS, and AWOS systems
• Approach Systems – providing wind data for ILS and other precision approach systems
• Runway Selection – helping ATC determine the active runway based on wind conditions
• Safety Systems – providing data for runway incursion prevention and emergency response

Wind sensors are also used at heliports, offshore platforms, and temporary airfields where portable weather stations are deployed.

Mounted on a mast or cross-arm sited in open, unobstructed air, following the same siting principles as the anemometer it is often paired with: clear of buildings, trees, and other masts by a wide margin, and set at the standard meteorological exposure height of around 10 m above ground level, or a lower touchdown-zone height where local practice dictates, to keep readings representative of the wind actually experienced on the runway. Multiple units are typically installed at different points along the airfield to cover local variation, each on its own mast with a concrete foundation and lightning protection and earthing appropriate to its height. Power and data cabling run underground in duct back to the AWOS/ATC display system, and the sensor head is aligned to true or magnetic north during commissioning so direction readings are accurate.

The wind sensor operates by measuring the movement of air and converting it into electrical signals. Common technologies include:

• Ultrasonic Sensors: Use pairs of ultrasonic transducers to measure the time-of-flight of sound pulses in different directions. The difference in travel time between pulses sent with and against the wind is used to calculate wind speed and direction. No moving parts, high accuracy, and low maintenance.
• Cup-and-Vane Sensors: A classic mechanical design where a rotating cup assembly measures wind speed (via a magnetic or optical encoder) and a wind vane measures direction (via a potentiometer or optical encoder). Simple, robust, and cost-effective.
• Hot-Wire Sensors: Use a heated wire or thermistor that is cooled by airflow. The cooling rate is proportional to wind speed, and the direction is determined by multiple sensors or a rotating head.

The sensor's electronics process the raw signals and output data via standard communication protocols (RS-485, SDI-12, NMEA, or digital outputs). The data is then fed into ATC displays, weather systems, and automated airfield systems. The sensor is typically housed in a weatherproof enclosure with heating to prevent ice buildup.

Unlike the windsock, the wind sensor is a fully active, addressable instrument with its own control loop rather than a purely mechanical indicator. The sensing element feeds raw signals to onboard signal-conditioning electronics, which digitise the measurement and output it over a standard interface (RS-485, SDI-12, NMEA, or 4-20mA). This is transmitted to a data acquisition unit (DAU) or data concentrator, which polls multiple meteorological sensors across the airfield and aggregates them into a single feed for the AWOS/ATIS processing system. From there, the data drives ATC wind displays, automated METAR/ATIS generation, and runway or approach selection logic. A separate, self-contained control loop operates the sensor's internal heater: a thermostat or RTD switches the heating element on once temperature falls below a set threshold, preventing ice from forming on the transducers or cups, entirely independent of the main measurement path. A heater fault is reported as a maintenance alarm rather than a wind-reading fault — at least until ice actually accumulates and begins to affect the reading.

An electronic wind sensor is built as a sealed instrument head containing the sensing elements — ultrasonic transducers, a cup-and-vane rotor assembly, or hot-wire elements, depending on technology — housed in a weatherproof enclosure of anodised aluminium or corrosion-resistant composite rated to IP66/IP67. Ultrasonic designs have no moving parts, with the transducer arms fixed rigidly to the sensor body so the acoustic path length between them remains precisely known; cup-and-vane designs instead rely on sealed, low-friction bearings supporting the rotating cups and directional vane, which are more exposed to mechanical wear and icing than a solid-state ultrasonic head. Many sensor heads incorporate internal heating elements around the transducer faces, bearings, or vane pivot to prevent ice accretion from stalling the mechanism or blocking the acoustic path in freezing conditions. The sensor mounts on a rigid pole or boom at the standard reference height, positioned clear of nearby structures or turbulence sources, with shielded, weather-rated cable carrying power and signal down to the base-mounted interface or data logger, and all external fasteners and housings built to withstand continuous, unsheltered outdoor exposure.