The changing of the seasons, also means a constant changing of high and low pressures which brings about considerable wind. These winds not only make things a lot bumpier than we would like up in the air, but they are also not always predictably on the nose. When crosswinds present themselves, these can quickly throw you off the runway if you are not prepared!
The first thing to do is to always be aware of the wind direction – if you are approaching an airport, this should be pretty easy as you can get this information from the ATIS, ATC or windsock. If none of these are available, check out our previous article on determining wind direction without a windsock. The next important factor is wind speed. It is important to note here that whether the wind speed is a lowly 5 knots or 25 knots, both of these can blow you off the runway if you do not prepare for them.
Apart from your piloting skills in dealing with crosswinds, each aircraft has a particular crosswind limitation, as determined by a test pilot, which can be found in the aircraft POH. Working out how much of a crosswind component you have is another story. The obvious ways to work it out are using the aircraft graphs, or a CX2 / CX3 calculator, but the reality is that one rarely has these on hand in flight, so how can we work out if the crosswind component is within our aircraft limits?
Time is usually lacking in the critical phases of flight, such as an approach for a landing, so this needs to be worked out quickly! I am not a maths boff at all, so I found the following method to be the easiest:
Take the wind speed, multiplied by the sine of wind angle (determined by working out the difference between the aircraft heading and the wind direction). For example, W/V = 310/25 Runway aircraft heading is 360 (Runway 36).
360 – 310 = 50 (wind angle) Now drop the zero = 5 and add 0.2
Crosswind component = wind speed(V) x sin(wind angle)
X = 25 x sin (50)
X = 25 x (5/10 + 0.2)
X = 25 x 0.7
X = 17.5 (rounded to 18kts)
If your aircraft limitation is 15kts, then 18kts would certainly produce undesirable results! This is also not to say that strong winds are the only culprits, light winds can also catch you off guard if you are not anticipating possible gusts or wind shear. Crosswinds are a normal part of flying, but being prepared will help you handle these situations like a pro.