The fact is, apart from your aerodrome, it is unlikely that you will find windsocks conveniently placed on your route, nor will every area be covered by ATIS reports, so how do you determine wind direction? More importantly, apart from take-offs and landings (where we normally have access to wind information), why do we need to pay attention to wind direction and speed during our flights?

If you read our previous article on downdrafts, then you will have realised that not being aware of wind direction and speed over rough or mountainous terrain can put you in more than a spot of bother. On the other hand, knowing where the wind is coming from can really help you should you need to land on a remote bush strip, or in the case of a precautionary or forced landing. Similarly, catching a tailwind will get you there quicker should a call of nature be pressing.

Every instructor seems to have an arsenal of suggestions of how to determine wind direction, and I think all of these have their merits depending on where you are flying:

DUST

Dust generated over ploughed fields or desert terrain provides an adequate indicator, should the terrain be dry enough. Dust trails are usually dependent on a mechanical disturbance, wind speed and the size of the particles. Larger particles require a stronger force to ‘lift’ them, but due to their weight will normally settle closer to the source. The further from the source you go, the lighter the particles. Therefore, the longer the ‘dust trail’ the stronger the wind, as the wind is able to carry the weight of particles for a longer distance.

SMOKE

Smoke is not guaranteed as a wind indicator, but in areas such as the Highveld in the Winter months, these are pretty common. The more the smoke trail leans into a certain direction, and the longer it is, the stronger the wind.

WAVES

Obviously this is not going to help if you are in the desert, but waves on water are a pretty good indicator of wind direction and speed. Waves generally run perpendicular to the direction of the wind, in other words, the wind is at 90 degrees to the wave line. The size and character of the waves also indicates wind speed. If the wavelets are small you can probably expect the wind to be around 5kts. If you are seeing ‘white caps’ on the waves, be it on a dam or the ocean, then the wind speed is closer to 15kts.

DRIFT METHOD

Your direction indicator (DI) is also a very useful instrument in determining wind direction. Pick an object or aiming point in the distance, take a note of the heading indication on your DI. Maintaining straight and level, with your aircraft in trim, keep flying towards the object. If you check your heading, you will notice that you have drifted off the original heading while still aiming for the same object. If you have drifted to the right, then the wind is coming from the left, and the opposite if you have drifted to the left. If your aircraft has a groundspeed indicator, then you can also determine if the wind is coming from the front or the rear – a higher groundspeed than indicated airspeed, shows that the wind is coming from the rear. In the case of an emergency, if you know the wind is right, then aim for the average on the right, so essentially, 90 degrees from your drifted heading.

Practising these techniques during a flight will not only improve your situational awareness, but will also improve your reaction time in the case of an emergency.