1:60 Rule

[Cook me some eggs Bitch!]

Not sure if Im in the right forum to ask this question, although Wannabees sounds pretty close.

Could somebody give me a rundown on the 1:60 rule?

Thanks in advance

[Matthewjharvey]

The 1:60 rule is basically saying that if you are 60 miles away from a given point and 1 degree off track then you will be 1 mile off track. If at the same distance you are 2 degrees off track then you will be 2 miles off track. If however you are only 30 miles from a point at one degree then you will 0.5 mile off track and so on.
The formula has a multitude of uses as well as navigation it can be used to calculate appropriate heights on an ILS for example which uses a 3 degree glide slope. So for example at 6DME you would theoretically be at (6/60) * 3 miles high = 2000 feet approx.

Hope this helps.

[Cook me some eggs Bitch!]

Thanks Greaser, much appreciated.

Its clear now.

[Chimbu chuckles]

Or track miles in a DME arc.

Chuck.

[Odi]

I'm not sure about its use to check height on an ILS glideslope - it isn't that accurate. A better judge for height on a 3 degree glideslope would be to use 300ft per nautical mile.

The 1 in 60 rule is only an approximation and is of no real use for angles of more than 25 degrees.

[Matthewjharvey]

Odi

300' / nm is the result you get using the 1:60 rule. My earlier comment that it should be 2000' was bollocks.

[rolling circle]

The 1:60 rule simply states that:

Track Error = Distance off track divided by Distance along track multiplied by 60

Thus, if an aircraft is 1 mile off track, having flown 60 miles along track, the Track Error is 1/60 x 60 = 1°. Alternatively, if an aircraft is 1km off track, having flown 30km along track, the Track Error is 1/30 x 60 = 2°. Note that the rule has nothing at all to do with either the number 60 or the unit 'miles', it will work with any measurement. Thus, if an aircraft is 2 bananas off track having flown 100 bananas along track, the Track Error is 2/100 x 60 = 1.2°

The 1:60 rule is developed from the fact that 1 radian (the angle at the centre of a circle that is subtended by an arc equal to the radius of the circle) is approximately equal to 60° (exactly equal to 57°17'44.81") and that, at small angles, the subtended arc is equal in length to a straight line normal to one of the radii. These approximations mean that the rule is of adequate accuracy at track errors only up to about 20-25°, but then none of us gets that far off track, do we???

This would be so much more convincing given a blackboard and chalk!

Edited to correct the mathematical error that nobody noticed.

[ 25 November 2001: Message edited by: rolling circle ]

[parkfell]

When I did a course with Sandy Thompson in 1992 at Booker [he then moved to Coventry] he was always "full of high class rubbish" as he called it.

The 1:60 rule should be the 1:57.3 rule

this comes under the heading of
de minimus non curat lex.

[DJXL]

6 DME on an ILS is 1800ft surely? Can you not just take the DME, multiplyit by 3 and add a couple of 00s?

1:60 rule used for everything else mind.