Oh, while I'm thinking about it, here's two "rules of thumb" for estimating the cross wind component, and a third one for estimating the headwind/tailwind component.

1. The Clock method. Figure out the "degrees off". So, for Runway 18, with a wind of 140/6, that's 40 degrees off. Now imagine where 40 would be on the clock face (it's under the 8, for all of you who only use digital watches). That's 8/12ths of the entire clock face, which reduces to 2/3rds.

2/3rds of the 6 knots of wind is 4 knots, and there's your estimate.

With this method, if you get 60 degrees off or larger, assume the crosswind is equal to the total wind velocity.

2. The 20% rule method. Again, figure out the degrees off. From the RWY 18 with winds at 140/6 example, again that's 40. Add 20, and use that percent of the wind as the crosswind component. 40+20=60. 60% of 6 knots= 3.6 knots of cross wind.

(By the way, the exact number is 6*sin (40)=3.857 knots, so they are both pretty good approximations).

With this method, you have to get to 80 degrees off before you assume that the crosswind is equal to the total wind velocity.

Okay what about head/tail wind. Well, figure out the degrees off and subtract that from 90. Then you can use the clock method or the 20% rule again.

RWY 18, winds 140/6 is 40 degrees off. 90-40=50. Clock method would give you 5/6ths (5 knots of head wind). 20% rule would give you 70% of 6, or 4.2 knots of head wind.

The exact number is 6*cos 40=4.596 knots.