Comments on: Calculating Distance with the 60:1 Rule http://wikirfm.cyclicandcollective.net Mon, 19 Dec 2011 00:39:37 +0000 hourly 1 http://wordpress.org/?v=3.3 By: MIke Dupuis http://wikirfm.cyclicandcollective.net/ground-lessons/calculating-distance-with-the-601-rule/comment-page-1/#comment-828 MIke Dupuis Tue, 15 Feb 2011 09:48:17 +0000 http://wikirfm.cyclicandcollective.net/?page_id=1361#comment-828 why not use the simpler (TIME IN SECONDS BETWEEN RADIAL CHANGE)/(DEGREES OF RADIAL CHANGE) equals TIME TO STATION IN MINUTES then /120=Distance to Station why not use the simpler

(TIME IN SECONDS BETWEEN RADIAL CHANGE)/(DEGREES OF RADIAL CHANGE) equals TIME TO STATION IN MINUTES then /120=Distance to Station

]]> By: Chris http://wikirfm.cyclicandcollective.net/ground-lessons/calculating-distance-with-the-601-rule/comment-page-1/#comment-672 Chris Thu, 01 Apr 2010 17:16:52 +0000 http://wikirfm.cyclicandcollective.net/?page_id=1361#comment-672 I added the emphasis in your post Mike. I remember watching a documentary about SR72 pilots. The one quote I remember is that "1 or 2 degrees is the difference between a successful mission and an international incident." I added the emphasis in your post Mike. I remember watching a documentary about SR72 pilots. The one quote I remember is that “1 or 2 degrees is the difference between a successful mission and an international incident.”

]]> By: Mike Franz http://wikirfm.cyclicandcollective.net/ground-lessons/calculating-distance-with-the-601-rule/comment-page-1/#comment-670 Mike Franz Sat, 20 Mar 2010 19:58:24 +0000 http://wikirfm.cyclicandcollective.net/?page_id=1361#comment-670 As to your beginning post about 60:1, most helo pilots will not be at suffient altitude to be 60 miles from a VOR and receive the station. Therefore my mention of flying an equi-distant arc really does not apply as your math showed how small the error would be. 60:1, 30:.5, 15:.25 As to your beginning post about 60:1, most helo pilots will not be at suffient altitude to be 60 miles from a VOR and receive the station. Therefore my mention of flying an equi-distant arc really does not apply as your math showed how small the error would be. 60:1, 30:.5, 15:.25

]]> By: Mike Franz http://wikirfm.cyclicandcollective.net/ground-lessons/calculating-distance-with-the-601-rule/comment-page-1/#comment-669 Mike Franz Sat, 20 Mar 2010 19:53:09 +0000 http://wikirfm.cyclicandcollective.net/?page_id=1361#comment-669 Dear Chris, I found the 60:1 rule useful during cross country instruction to stress the importance of flying a desired heading. I tell pilots that are constantly off the desired heading that if they are <strong>off course just 5 dgrees in a 120nm flight we can be 10 miles off at the expected time of arrival</strong>. Hopefully many would use good navigation enroute to make off course corrections and fly a desired heading. This was especially important on a VFR flight from Miami to Puerto Rico when spending a lot of time over open ocean with NO reference points and trying hard not to mistake the shadows from clouds as islands in the distance. Dear Chris, I found the 60:1 rule useful during cross country instruction to stress the importance of flying a desired heading. I tell pilots that are constantly off the desired heading that if they are off course just 5 dgrees in a 120nm flight we can be 10 miles off at the expected time of arrival. Hopefully many would use good navigation enroute to make off course corrections and fly a desired heading. This was especially important on a VFR flight from Miami to Puerto Rico when spending a lot of time over open ocean with NO reference points and trying hard not to mistake the shadows from clouds as islands in the distance.

]]> By: Chris http://wikirfm.cyclicandcollective.net/ground-lessons/calculating-distance-with-the-601-rule/comment-page-1/#comment-668 Chris Fri, 19 Mar 2010 19:45:48 +0000 http://wikirfm.cyclicandcollective.net/?page_id=1361#comment-668 No surprise here: you are absolutely correct Mike! As you point out, if you start 60 nm from the VOR and fly on a constant heading until you cross 1 radial, you won't be 60 nm from the VOR anymore...you'll actually be a little further from it (use the Pythagorean theorem to figure out that you'll be 60.008 nm). This error grows as you cross more radials--by the time you crossed 20 radials, you would in fact be 63 nm from the VOR. If you fly over just a few radials, the difference is pretty small. You can cross 12 radials be within 2% of the correct distance, which isn't too bad. Over 20 radials (at 60 nm), the difference gets to be >5%. Just from doing a few sample calculations, it looks like most of the time, if you don't cross too many radials, you can estimate your distance to within +/-5%. One of the problems that I have with the explanation of the 60:1 rule in the Jeppesen book is that they don't explain the rationale behind it, but instead just slap out some formulas. If that's all you know, then 1) it's harder to solve 60:1 problems and 2) you wouldn't be able to recognize limitations to the method, like this particular one. Now the sad reality: this probably won't ever be more than a test question for most guys, and one that could be memorized (there are only a few of these questions on the knowledge exam). In that case, you aren't trying to figure out if you're over airport A or airport B, you're trying to select between answer A and answer B. The 60:1 problems are neat to think through...thanks for raising this important caveat! No surprise here: you are absolutely correct Mike! As you point out, if you start 60 nm from the VOR and fly on a constant heading until you cross 1 radial, you won’t be 60 nm from the VOR anymore…you’ll actually be a little further from it (use the Pythagorean theorem to figure out that you’ll be 60.008 nm). This error grows as you cross more radials–by the time you crossed 20 radials, you would in fact be 63 nm from the VOR.

If you fly over just a few radials, the difference is pretty small. You can cross 12 radials be within 2% of the correct distance, which isn’t too bad. Over 20 radials (at 60 nm), the difference gets to be >5%. Just from doing a few sample calculations, it looks like most of the time, if you don’t cross too many radials, you can estimate your distance to within +/-5%. One of the problems that I have with the explanation of the 60:1 rule in the Jeppesen book is that they don’t explain the rationale behind it, but instead just slap out some formulas. If that’s all you know, then 1) it’s harder to solve 60:1 problems and 2) you wouldn’t be able to recognize limitations to the method, like this particular one.

Now the sad reality: this probably won’t ever be more than a test question for most guys, and one that could be memorized (there are only a few of these questions on the knowledge exam). In that case, you aren’t trying to figure out if you’re over airport A or airport B, you’re trying to select between answer A and answer B.

The 60:1 problems are neat to think through…thanks for raising this important caveat!

]]> By: Mike Franz http://wikirfm.cyclicandcollective.net/ground-lessons/calculating-distance-with-the-601-rule/comment-page-1/#comment-667 Mike Franz Fri, 19 Mar 2010 19:10:32 +0000 http://wikirfm.cyclicandcollective.net/?page_id=1361#comment-667 Yo, Chris, you are correct in theory with the exception of flying a constant heading! Think about this, If you crossed 20 radials flying a constant heading ( no wind for now) you would not be the same distance from the nav aid unless you flew an arc(like a DME arc). Pull out a sectional, go to a VOR, pick a radial and about 60 miles out draw a course line perpendicular to the radial. Then measure the distance along a radial 20 degrees different. Or measure from the nav aid to a point on the line of +20 degree radial. It will be a greater distance. Yo, Chris, you are correct in theory with the exception of flying a constant heading! Think about this, If you crossed 20 radials flying a constant heading ( no wind for now) you would not be the same distance from the nav aid unless you flew an arc(like a DME arc). Pull out a sectional, go to a VOR, pick a radial and about 60 miles out draw a course line perpendicular to the radial. Then measure the distance along a radial 20 degrees different. Or measure from the nav aid to a point on the line of +20 degree radial. It will be a greater distance.

]]> By: The 60:1 Rule | http://wikirfm.cyclicandcollective.net/ground-lessons/calculating-distance-with-the-601-rule/comment-page-1/#comment-666 The 60:1 Rule | Mon, 08 Mar 2010 19:17:46 +0000 http://wikirfm.cyclicandcollective.net/?page_id=1361#comment-666 [...] Calculating Distance with the 60:1 Rule [...] [...] Calculating Distance with the 60:1 Rule [...]

]]>