Weston Airport EIWT, Co. Kildare: wind, crosswind and gusts

Weston Airport operates two primary runways: a paved main runway and a grass runway. The main runway, designated 07/25, is oriented approximately east-north-east to west-south-west. The grass runway, 07R/25L, runs parallel to the main runway. Understanding these orientations is crucial for assessing crosswind and headwind components.

• Runway 07/25: Heading approximately 070° / 250° (magnetic).

Pilots commonly use the instrument to calculate the crosswind and headwind components for their specific aircraft's limits, ensuring operations remain within the manufacturer's guidance and operator's standard operating procedures. The Shear Glass provides height-matched wind data, which is relevant for approach and landing phases where wind shear can be a factor. The instrument does not provide go/no-go advice, but rather reports the wind, gusts, and crosswind components against the limits set by the user.

Crosswind and headwind components are derived from the meteorological wind direction and speed relative to the runway heading. A direct headwind or tailwind (wind aligned with the runway) results in zero crosswind. As the wind direction deviates from the runway heading, the crosswind component increases, while the headwind component decreases (or becomes a tailwind).

For a wind of 20 knots from 300° (NW) on Runway 25 (heading 250°):

1. Angle between wind and runway: 300° - 250° = 50°.
2. Crosswind component: 20 knots * sin(50°) ≈ 15.3 knots.
3. Headwind component: 20 knots * cos(50°) ≈ 12.9 knots.

Typical manufacturer limits for crosswind vary significantly by aircraft type, but values of 15–25 knots are commonly cited for light aircraft. For example, a Cessna 172's demonstrated crosswind component is commonly cited around 15 knots, while some larger aircraft may have limits exceeding 30 knots. It is essential for pilots to consult their aircraft's Pilot's Operating Handbook (POH) for specific limitations.

The Wind Agent's crosswind metric directly supports this calculation, allowing pilots to input their specific runway heading and see the forecast components.

Gusts are transient increases in wind speed, typically lasting less than 20 seconds. They are reported as the maximum observed wind speed during a specified period (e.g., 10 minutes). For aviation, gusts are particularly significant during take-off, approach, and landing phases, as they can cause sudden changes in lift and control authority.

The gust factor, commonly defined as the ratio of gust speed to mean wind speed, typically ranges from 1.2 to 1.5 in open terrain. However, this factor can be higher in turbulent conditions, such as those associated with convective activity or terrain effects.

Pilots commonly consider gust spreads (the difference between the mean wind speed and the gust speed) when assessing conditions. A gust spread exceeding 10 knots is often cited by instructors as a threshold requiring increased caution, particularly for less experienced pilots or in lighter aircraft. The Wind Agent provides both mean wind speed and gust speed, enabling pilots to calculate this spread and assess the potential for turbulence.

Low-level wind shear is a significant aviation hazard, characterised by a sudden change in wind speed or direction over a short distance, typically within 600 metres (approximately 2,000 feet) of the ground. It can occur horizontally, vertically, or both, and is often associated with frontal passages, thunderstorms, sea breezes, or terrain effects.

Wind shear can cause unexpected changes in indicated airspeed, leading to significant deviations from the intended flight path during take-off and landing. A sudden decrease in headwind can result in a loss of airspeed and lift, while an increase can lead to an unexpected climb. The Shear Glass instrument in The Wind Agent provides height-matched wind data at 10, 80, 120, and 180 metres, allowing pilots to assess potential wind shear across typical approach and departure altitudes. This vertical profile of wind is crucial for anticipating changes in wind conditions during critical flight phases.

The meteogram provides a detailed forecast of wind speed, gust, and direction for Weston Airport over the coming days. This allows pilots to assess the overall wind pattern, identify periods of higher winds or significant gusts, and plan their flights accordingly. The forecast is derived from high-resolution meteorological models, providing a dynamic view of expected conditions.

For real-time observations, pilots commonly refer to METAR (Meteorological Aerodrome Report) reports. While The Wind Agent focuses on forecast data, the nearby stations listed can provide current measured conditions. Comparing forecast models with recent observations helps to build confidence in the forecast and identify any discrepancies.

The exceedance fan tool allows pilots to set their specific crosswind or gust limits and visualise the probability of exceeding these limits at different heights, providing a probabilistic assessment of risk for their operations.

The prevailing wind direction in Ireland, and specifically in the Kildare region, is predominantly from the south-west to west. This means that for Weston Airport, winds from these directions will often present a headwind or crosswind component on Runway 07/25, depending on the exact angle.

The wind rose for Weston Airport illustrates the frequency and intensity of winds from different directions based on historical data. This climatological perspective is valuable for long-term planning and understanding typical conditions. For example, a strong south-westerly flow might mean a significant headwind on Runway 25 or a crosswind on Runway 07.

Seasonal variations also play a role. Winter months (October to March) typically experience stronger winds and more frequent frontal systems, leading to higher average wind speeds and more pronounced gusts. Summer months tend to have lighter winds, though convective activity can still produce localised strong gusts and wind shear.