Distance to fly an arc
Distance to fly an arc
Guest
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Calculate the total circumference of the circle using pi. Divide as required. i.e in this case by 4. There's your answer. I realise that you already know this but quite honestly once you have done it a few times in the air it's fairly easy.
I think that your question is good because you are obviously thinking about the vertical profile of your approach routing. Your future Captains will appreciate flying with a colleague who doesn't have to level out for 12 miles during a DME ARC procedure because he was only thinking about the lateral plot.
I think that your question is good because you are obviously thinking about the vertical profile of your approach routing. Your future Captains will appreciate flying with a colleague who doesn't have to level out for 12 miles during a DME ARC procedure because he was only thinking about the lateral plot.
Guest
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The circumference of a circle is 2πr where r is the radius and π is 3.14159265358979323846264338327950288419716 (approximately). 
Therefore, if you are going to fly through 20 degrees of arc on a 12 dme arc, you will fly (2π x 12 x 20)/360 = 4.2 nm approx.
The formula can be simplified to (radius x arc)/60.
In your example, the distance flown is 22.5 miles. Using a closer approximation for π, we get 23.561946 nm, but the first is probably good enough for government work!
Therefore, if you are going to fly through 20 degrees of arc on a 12 dme arc, you will fly (2π x 12 x 20)/360 = 4.2 nm approx.
The formula can be simplified to (radius x arc)/60.
In your example, the distance flown is 22.5 miles. Using a closer approximation for π, we get 23.561946 nm, but the first is probably good enough for government work!
Guest
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Arc flying for dummies:
HugMonsters simplified formula can be simplified even more by memorizing two numbers; 6 and 3.
Flying a 10-mile arc you will cover a mile for each 6 radials.
Flying a 20-mile arc you will cover a mile for each 3 radials.
Example:
30 degrees to go on a 10-mile arc: 30/6=5nm to go.
30 degrees to go on a 20-mile arc: 30/3=10nm to go.
For other arc's you can interpolate using these two numbers
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"Recovery was marginal..."
HugMonsters simplified formula can be simplified even more by memorizing two numbers; 6 and 3.
Flying a 10-mile arc you will cover a mile for each 6 radials.
Flying a 20-mile arc you will cover a mile for each 3 radials.
Example:
30 degrees to go on a 10-mile arc: 30/6=5nm to go.
30 degrees to go on a 20-mile arc: 30/3=10nm to go.
For other arc's you can interpolate using these two numbers
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"Recovery was marginal..."
Guest
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How about the good ol 1:60 rule.
As exampled earlier,12nm arc through 20deg=4 track miles(20/5=12).Try a 15nm arc through say 100deg (100/4=25nm).
Sorry guys,knw how to do it,cant explain myself very well,but it works really well and quick to work out in your head!!
As exampled earlier,12nm arc through 20deg=4 track miles(20/5=12).Try a 15nm arc through say 100deg (100/4=25nm).
Sorry guys,knw how to do it,cant explain myself very well,but it works really well and quick to work out in your head!!
Guest
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Just multiply the arc (radius) by 6 (2n=2*3.14), you will get circumfrence distance (that is distance for the entire circle if you were to fly the complete circle). Now if you are to fly 60 degrees: 60 degrees is 1/6 (16%) of a 360 degrees circle ( 60/360 ). So if u are flying 15 Nm. arc for 60 degrees total distance flown is 14 miles.
(DME ARC*6)* factor of 360 degrees (degrees to fly/360)
I hope it's not too complicated; a bit of arithmetic fluency really helps.
(DME ARC*6)* factor of 360 degrees (degrees to fly/360)
I hope it's not too complicated; a bit of arithmetic fluency really helps.
Guest
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najib, arc is not the same as radius.
You've also very successfully managed to complicate a very simple calculation.
Why multiply the radius by 6, divide by 360 and multiply again by the arc angle?
You get the same result radius x arc / 60.
e.g. 10 dme arc (circle radius 10 miles) - 30 degrees of arc.
10x30=300
300/60=5
Easy, no?
You've also very successfully managed to complicate a very simple calculation.
Why multiply the radius by 6, divide by 360 and multiply again by the arc angle?
You get the same result radius x arc / 60.
e.g. 10 dme arc (circle radius 10 miles) - 30 degrees of arc.
10x30=300
300/60=5
Easy, no?
Guest
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Hey, I was attempting the query from a conceptual point of view. So if one forgets which number to divide by, then he/she can derive. Some people are good in remembering the formula and some are good in understanding the theory. Anyway, as long as oxfordg1 is happy, we are happy!
Guest
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check this one. It is simple and precise
if you fly a 60º arc yu are flying the arc distance hence a 90º arc you will be flying 1.5 times the arc.
what about a 30º arc?
got it?
if u dont let me know and with a few more examples i am sure u will get it.
se ya
if you fly a 60º arc yu are flying the arc distance hence a 90º arc you will be flying 1.5 times the arc.
what about a 30º arc?
got it?
if u dont let me know and with a few more examples i am sure u will get it.
se ya
Guest
Posts: n/a
Arc discussed on Dunnunda Thumb Rules thread, inter alia. From that discussion... one in sixty works well.
On a sixty mile arc, you change bearing one degree per mile flown.
30DME arc, two degrees per mile,
20DME, three per mile
15DME, four per mile
12DME, five per mile
10DME, six per mile
9DME, seven per mile
8DME, eight per mile
7DME, nine per mile
6DME, ten per mile
Less than 5DME, write a complaint to the issuing agency, because it is too small.
Anything in between, interpolate because you will be bloody close.
Also note that if your RMI is marked in 5 degree increments, each mark on a 12DME arc represents a mile flown/to fly. If you are incorporating a descent profile like 3nm per 1000 feet to lose, that is 1000 feet per three divisions on a 12DME arc.
With numeric skills like that, you think my countrymen could do something about the aussie dollar. <sigh>.
[This message has been edited by ITCZ (edited 10 April 2001).]
On a sixty mile arc, you change bearing one degree per mile flown.
30DME arc, two degrees per mile,
20DME, three per mile
15DME, four per mile
12DME, five per mile
10DME, six per mile
9DME, seven per mile
8DME, eight per mile
7DME, nine per mile
6DME, ten per mile
Less than 5DME, write a complaint to the issuing agency, because it is too small.
Anything in between, interpolate because you will be bloody close.
Also note that if your RMI is marked in 5 degree increments, each mark on a 12DME arc represents a mile flown/to fly. If you are incorporating a descent profile like 3nm per 1000 feet to lose, that is 1000 feet per three divisions on a 12DME arc.
With numeric skills like that, you think my countrymen could do something about the aussie dollar. <sigh>.
[This message has been edited by ITCZ (edited 10 April 2001).]
