# 2 questions

#### Fly_Unity

##### Well-Known Member
unrelated...

First.. is there a formula somewhere where I can figure out how much wind drift is coming from left or right while flying? like lets say my ground track is 10 degrees to the left of where the nose is pointed, and im going 100 knots. how much cross wind is there? (without using an E6B)

I work line some days, and sometimes when fueling airplanes, the wind isn't right and I have to smell Jet fuel during the whole fueling process. Is this dangerous? A guy just told me that Jet A and Diesel wont hurt you like 100LL or unleaded.

#### tgrayson

##### New Member
First.. is there a formula somewhere where I can figure out how much wind drift is coming from left or right while flying? like lets say my ground track is 10 degrees to the left of where the nose is pointed, and im going 100 knots. how much cross wind is there? (without using an E6B)
http://en.wikipedia.org/wiki/Law_of_sines

#### Fly_Unity

##### Well-Known Member
Thankyou... I guess I'll have to spend some time trying to figure out how to do that.

#### JulietBravo

##### On Call, On Demand
unrelated...

First.. is there a formula somewhere where I can figure out how much wind drift is coming from left or right while flying? like lets say my ground track is 10 degrees to the left of where the nose is pointed, and im going 100 knots. how much cross wind is there? (without using an E6B)

I work line some days, and sometimes when fueling airplanes, the wind isn't right and I have to smell Jet fuel during the whole fueling process. Is this dangerous? A guy just told me that Jet A and Diesel wont hurt you like 100LL or unleaded.
For the first ?... Just look in the corner on the G1000... lol :laff:

And I Breathed Jet-A for 4 months straight... even got soaked in it a couple days (gotta love filling those FedEx C208!!)... and I'm doing just fine.... at least i think so... anic:

#### fish314

##### Well-Known Member
Here's a rule of thumb that you can use to find the drift correction. Take the cross wind component and divide it by your miles/minute.

So let's say that you are doing about 110 indicated on an approach, I'd call it about 120 knots true (even though I know it will probably be less, it will give me an even number to work with-- 2 miles per minute).

Now if I know the cross wind component is 6 knots, then 6/2=3. 3 degrees of crab into the wind should be about right.

Using that formula, you can work in reverse to find the cross wind component. If you are doing 100 knots true ( 5/3 NM/min) multiply by the crab angle, and you'll get an approximation of the cross wind component. In the example you gave, 10 degrees of crab * 5/3 miles/minute=16.666 knots of cross. Keep in mind this is a "rule of thumb" so the numbers don't work out EXACTLY, but they get you close. Taylor gave you the exact number, but this might be easier to use in flight.

#### fish314

##### Well-Known Member
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.

#### ppragman

##### FLIPY FLAPS!
unrelated...

First.. is there a formula somewhere where I can figure out how much wind drift is coming from left or right while flying? like lets say my ground track is 10 degrees to the left of where the nose is pointed, and im going 100 knots. how much cross wind is there? (without using an E6B)

I work line some days, and sometimes when fueling airplanes, the wind isn't right and I have to smell Jet fuel during the whole fueling process. Is this dangerous? A guy just told me that Jet A and Diesel wont hurt you like 100LL or unleaded.

I don't think I believe that at all. When I was an FO at ACE, the copilots were the "Fueling Officer/Flap Operator" and had to fill up the 1900 before flight. That's all well and dandy except for the 1900 does not have single point fueling (at least the C model doesnt, not sure about the D) and the tanks are kinda a pain to fuel, and you're always belching fuel onto yourself if your not careful. After a month there I was exuding jet A out of my skin (kind of hard be awake when you woke up at 1:30AM for a flight). And that cannot be good for you.

O... M... G...

#### CoffeeIcePapers

##### Well-Hung Member
Both Jet-A and 100LL are cancerous, I think Jet-A is even worse. Your employer should have a MSDS you can look at. I believe it is Benzene that is the culprit.

#### Dmitri Ivanov

##### New Member
I am to think your mathematic is incorrect. Your airplane is going incorrect. What you have called actual track should be the airplane and it should have only 100 length. The airplane called side is to be the shorter than the actual track.

#### tgrayson

##### New Member
I am to think your mathematic is incorrect.
That's possible. However, the numbers work out exactly when I plug them into an E6B.

What you have called actual track should be the airplane and it should have only 100 length.
I don't think so. That's the resulting ground speed when taking into account the wind. It will be 2 knots higher with this scenario.

The airplane called side is to be the shorter than the actual track.
It is.

#### fish314

##### Well-Known Member
I am to think your mathematic is incorrect. Your airplane is going incorrect. What you have called actual track should be the airplane and it should have only 100 length. The airplane called side is to be the shorter than the actual track.
Dmitri,

Could the confusion be the way that tgrayson labeled the diagram? If instead of "airplane" he had used the words "true airspeed," would that make it seem correct?

#### Dmitri Ivanov

##### New Member
Dmitri,

Could the confusion be the way that tgrayson labeled the diagram? If instead of "airplane" he had used the words "true airspeed," would that make it seem correct?
Yes! The issue is this!

#### tgrayson

##### New Member
Yes! The issue is this!
Isn't science great? We can have a disagreement, discuss it, find out where the error lies, and then we're all in agreement.

Now if only the politicians and religious folks could follow our example....