Originally Posted by
florens
However, this would be a 90 degrees angle. The crosswind component here is lower than the wind speeds shown in the METAR. There is a formula to calculate the component. I don‘t know it by heart though.
Firstly any calculation need to including gusts not just steady wind.
Crosswind speed = wind speed x sin(α)
α = (Wind speed heading°) - (aircraft heading°), and where - 90° < α < +90°
In simple terms a wind at 90° to the runway heading (so for LHR this would be wind from 180° or 360°) would be all crosswind and sin(α) would be 1, whereas as a wind in line with the runway would have no crosswind component and sin(α) would be 0. It's not linear in between those two extremes though.
For today runway is 270° and wind at 210° 20kts gusting 35kts
the crosswind component would be = 35 x sin (270-210) = 35 x 0.86 =
up to 30kts crosswind on the gusts