1:60 rule
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1:60 rule
Hi ppruners,
Does anyone have any easy methods/techniques for the 1:60 rule? Even now i'm still struggling to get my head around it. I understand about using 'fan-lines' to determine how far you are off track, and to get back on track you have to double your 'off-track' angle. But I know that this depends upon how far you are along the 60 mile section. An instructor siad that if you're a quarter of the way along your route you divide the correction angle by 1/4 or something like that. So far i've never needed it as so far i've never needed to use it. But should the day I need it come ...
Any help/techniques would be gratefully appreciated
PC
Does anyone have any easy methods/techniques for the 1:60 rule? Even now i'm still struggling to get my head around it. I understand about using 'fan-lines' to determine how far you are off track, and to get back on track you have to double your 'off-track' angle. But I know that this depends upon how far you are along the 60 mile section. An instructor siad that if you're a quarter of the way along your route you divide the correction angle by 1/4 or something like that. So far i've never needed it as so far i've never needed to use it. But should the day I need it come ...
Any help/techniques would be gratefully appreciated
PC
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The whole point of the exercise, having realised that you are off track and determined by roughly how much, is to work out a rough course which will get you going in the right direction. In practice this could be either getting back to your original track, or a new track direct to your destination/next waypoint.
Now, how you do this is entirely up to you, as long as your method is reasonably quick and accurate (so that you do not make the situation worse, possibly bust airspace, etc.) What the instructor is teaching you is purely one suggested method, it is advisory not compulsory (although he might want you to demonstrate it, just humour him and move on).
Personally, when dead-reckoning[*] I just have a look at the chart once in a while, then if I have to say "Bugger, I'm a mile off", I proceed to eyeball the new track and fly a roughly suitable heading. Sometimes there is a feature you can aim for to make life easier.
If flying under a radar service then another option is to simply ask for a vector. Then there is the GPS and other navaids, but that entails having to work buttons and dials and adds to your workload.
In summary, just use the simplest method which works for you.
[*] Pre-emptive note to IO540: I know, I know... but some of us actually like doing a bit of dead reckoning for the fun of it. Ideally in a no-radio, open cockpit biplane, for better WW1 effect
Now, how you do this is entirely up to you, as long as your method is reasonably quick and accurate (so that you do not make the situation worse, possibly bust airspace, etc.) What the instructor is teaching you is purely one suggested method, it is advisory not compulsory (although he might want you to demonstrate it, just humour him and move on).
Personally, when dead-reckoning[*] I just have a look at the chart once in a while, then if I have to say "Bugger, I'm a mile off", I proceed to eyeball the new track and fly a roughly suitable heading. Sometimes there is a feature you can aim for to make life easier.
If flying under a radar service then another option is to simply ask for a vector. Then there is the GPS and other navaids, but that entails having to work buttons and dials and adds to your workload.
In summary, just use the simplest method which works for you.
[*] Pre-emptive note to IO540: I know, I know... but some of us actually like doing a bit of dead reckoning for the fun of it. Ideally in a no-radio, open cockpit biplane, for better WW1 effect
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PC:
No offence to my fellow ppruners but the best way to get your head round use of the 1:60 rule is to read the text book - Jeremy Pratt, Trevor Thom, whichever is your preference.
The basic starting point is that if you're one mile off track after flying straight for 60 miles, you will be one DEGREE off track. When in the air you can use multiples/fractions of that to work out how many degrees off track you are. But 1 in 60 has many more uses than that.
NS
No offence to my fellow ppruners but the best way to get your head round use of the 1:60 rule is to read the text book - Jeremy Pratt, Trevor Thom, whichever is your preference.
The basic starting point is that if you're one mile off track after flying straight for 60 miles, you will be one DEGREE off track. When in the air you can use multiples/fractions of that to work out how many degrees off track you are. But 1 in 60 has many more uses than that.
NS
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In my opinion the best thing to do with the 1in60 rule is not bother with it. Skills tests will load your brain fairly heavily as it is, and trying to figure out the 1in60 rule in flight doesn't help.
On my CPL test I just used closing angle corrections to regain the original track, then correct the heading for unforecast wind etc... much easier to remember.
On my CPL test I just used closing angle corrections to regain the original track, then correct the heading for unforecast wind etc... much easier to remember.
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The 1 in 60 rule is excellent over areas without visual navigational features, water, desert, unpopulated areas but for general navigation in this country most people make small corrections to map read themselves back onto track based on 5, 10 or 20 degree corrections left or right as appropriate. Practice with a map using both the rule and guestimation, you will find you will be always close to the calculation
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Try:
60 dots on the dog!
ie:
60 x Distance off track
___________________
distance gone
That then gets you parallel to original course.
Try doubling it to get back on track in the same number of miles that it took you to get off track.
But remember if getting near the Manchester low level corridor or the Kilmarnock corridor - for instance - you could then bust controlled airspace as you get back on track!
Waste of space in UK, one of those classics from the 1920s that everyone still teaches but is off little practical use.
60 dots on the dog!
ie:
60 x Distance off track
___________________
distance gone
That then gets you parallel to original course.
Try doubling it to get back on track in the same number of miles that it took you to get off track.
But remember if getting near the Manchester low level corridor or the Kilmarnock corridor - for instance - you could then bust controlled airspace as you get back on track!
Waste of space in UK, one of those classics from the 1920s that everyone still teaches but is off little practical use.
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The basic starting point is that if you're one mile off track after flying straight for 60 miles, you will be one DEGREE off track.
In real life if you are one mile to the left of where you should be, you point right "a bit" until you're back on track. The best way to do this, as others have said, is to spot something out of the window that is on the correct track, and aim at it.
The really clever trick is to have a quick look at the map and ask yourself a question like "if I am a mile to the left of where I should be, have I already busted controlled airspace, and, if not, how quickly will I do so if I carry on like this?". From this you can have a guess as to how much "a bit" is.
There's really no point (if you've got a brain like mine) trying to remember bizarre and arbitrary "one in sixty" rules. Where the "one in sixty" rule comes from is the "facts" that
- pi is three, near enough
- sin(x) is x, near enough, for small x, and I'm only ever going to be off course by a small angle, aren't I, honest guv
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Err... I assumed the original poster knew what the 1:60 rule is, and was asking about how it's applied in PPL navigation. But re-reading, maybe I was wrong.
The 1 in 60 is a rule of thumb, i.e., a simplification of some formula or principle which can be applied with minimum calculation effort. As a simplification, it's meant to be just "good enough", which is why you use them for sorting out small nav errors for example, but not for calculating TODR on a commercial flight (although you would still have a rough guesstimate in your head, to catch any gross errors).
As regards the problem at hand, your goal is to identify your track error--e.g., say you were supposed to be flying a track of 210°, but 60nm from your last waypoint, you cross-check on the map, and that feature you were expecting to overfly is not directly below the plane but, you estimate, about 1nm to one side (say on your right hand side). Now you know that whichever track you were flying, it wasn't 210° but something else, and you would like to have an idea of what that something else might have been so that you can come up with a strategy to get back on track.
This is simple trigonometry, where you have a right triangle formed by sides (a), (b), and (c), and angles (A), (B), and (C), where for the sake of argument we call (a) the hypotenuse, formed by the distance flown from your last waypoint (where your track error was zero), (b) your distance off track perpendicular to your planned track, and (A) is the 90° angle, opposite (a). If you can bear my ASCII art:
..........(B)
..........*
..........|.\
..........|..\
.....(c).|...\..(a)
..........|....\
..........|___\
.....(A)..(b)...(C)
(The dots are to stop this piece of **** of a so-called bulletin board eating up the spaces
)
Now, we know that knowing at least one side and any two other elements, we can solve for the remaining elements of a triangle. In our case, we know the two sides (a) and (b) and the one angle (A) = 90°, and our goal is to find the angle (B). From Euclidean trigonometry we have that (B) = atan(b/a). In our example: (B) = atan(1/60) ~= 0.95484° which is roughly one arc degree.
So now hopefully you see where the 1:60 rule comes from: for small angles, one arc degree subtends approximately one unit of length every sixty units of length (of course it doesn't matter which units you choose, be they nautical miles, metres, fathoms, smoots, or your maternal uncle elbow's length). This rule of thumb holds true to within about a 5% error for angles less than 8°, and within a 10% error for angles less than 20°.
Now for practical applications on a navex you've got to options: you can either wait until you've flown for 60 nautical miles to ascertain your cross track error, or you can use cross-multiplication. So if for example you have flown for 30nm and you estimate your cross-track error to be 2nm, then (1/60)/1 = (2/30)/xte => xte = (2/30)/(1/60) = 60/15 = 4. Your track was about 4° in error, and knowing this you now can come up with a course correction strategy for either getting back on track or proceeding direct to your destination. The simplest strategy is that if you now fly a track which is 4° less (if you are right of track) or more (if you are left of track) than the original track, for a distance equal to your elapsed distance from the last waypoint, you will regain your original track (at which point you should make a new course correction of 4° in the opposite sense as before, or you will overshoot). Note that, because you were flying a track 4° in error, and when you make your correction essentially you will be flying another 4° in error in the opposite sense, you will make an 8° turn.
From simple logic, it follows that if you want to regain track faster you will apply a bigger correction. E.g., 8° correction [12° turn]) and you will regain track in half your elapsed distance, and so on and so forth. Another strategy is simply to work out a new track to your next waypoint (by drawing a new line on your map), or to spot an easily identifiable feature such as a village (do not misidentify) or a valley (idem) which lies on your original track and fly to it. In every case, make sure you are not going to get in trouble by doing whatever you've decided to do (airspace, terrain, weather, etc.). If in doubt, a 90° turn might be a sensible option.
Anyhow, hopefully that's the 1:60 rule explained. I haven't got time to re-read the above so apologies for any errors or omissions. HTH.
The 1 in 60 is a rule of thumb, i.e., a simplification of some formula or principle which can be applied with minimum calculation effort. As a simplification, it's meant to be just "good enough", which is why you use them for sorting out small nav errors for example, but not for calculating TODR on a commercial flight (although you would still have a rough guesstimate in your head, to catch any gross errors).
As regards the problem at hand, your goal is to identify your track error--e.g., say you were supposed to be flying a track of 210°, but 60nm from your last waypoint, you cross-check on the map, and that feature you were expecting to overfly is not directly below the plane but, you estimate, about 1nm to one side (say on your right hand side). Now you know that whichever track you were flying, it wasn't 210° but something else, and you would like to have an idea of what that something else might have been so that you can come up with a strategy to get back on track.
This is simple trigonometry, where you have a right triangle formed by sides (a), (b), and (c), and angles (A), (B), and (C), where for the sake of argument we call (a) the hypotenuse, formed by the distance flown from your last waypoint (where your track error was zero), (b) your distance off track perpendicular to your planned track, and (A) is the 90° angle, opposite (a). If you can bear my ASCII art:
..........(B)
..........*
..........|.\
..........|..\
.....(c).|...\..(a)
..........|....\
..........|___\
.....(A)..(b)...(C)
(The dots are to stop this piece of **** of a so-called bulletin board eating up the spaces
)Now, we know that knowing at least one side and any two other elements, we can solve for the remaining elements of a triangle. In our case, we know the two sides (a) and (b) and the one angle (A) = 90°, and our goal is to find the angle (B). From Euclidean trigonometry we have that (B) = atan(b/a). In our example: (B) = atan(1/60) ~= 0.95484° which is roughly one arc degree.
So now hopefully you see where the 1:60 rule comes from: for small angles, one arc degree subtends approximately one unit of length every sixty units of length (of course it doesn't matter which units you choose, be they nautical miles, metres, fathoms, smoots, or your maternal uncle elbow's length). This rule of thumb holds true to within about a 5% error for angles less than 8°, and within a 10% error for angles less than 20°.
Now for practical applications on a navex you've got to options: you can either wait until you've flown for 60 nautical miles to ascertain your cross track error, or you can use cross-multiplication. So if for example you have flown for 30nm and you estimate your cross-track error to be 2nm, then (1/60)/1 = (2/30)/xte => xte = (2/30)/(1/60) = 60/15 = 4. Your track was about 4° in error, and knowing this you now can come up with a course correction strategy for either getting back on track or proceeding direct to your destination. The simplest strategy is that if you now fly a track which is 4° less (if you are right of track) or more (if you are left of track) than the original track, for a distance equal to your elapsed distance from the last waypoint, you will regain your original track (at which point you should make a new course correction of 4° in the opposite sense as before, or you will overshoot). Note that, because you were flying a track 4° in error, and when you make your correction essentially you will be flying another 4° in error in the opposite sense, you will make an 8° turn.
From simple logic, it follows that if you want to regain track faster you will apply a bigger correction. E.g., 8° correction [12° turn]) and you will regain track in half your elapsed distance, and so on and so forth. Another strategy is simply to work out a new track to your next waypoint (by drawing a new line on your map), or to spot an easily identifiable feature such as a village (do not misidentify) or a valley (idem) which lies on your original track and fly to it. In every case, make sure you are not going to get in trouble by doing whatever you've decided to do (airspace, terrain, weather, etc.). If in doubt, a 90° turn might be a sensible option.
Anyhow, hopefully that's the 1:60 rule explained. I haven't got time to re-read the above so apologies for any errors or omissions. HTH.
Last edited by LH2; 19th Jul 2009 at 23:17. Reason: Fixed ASCII art
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(The dots are to stop this piece of **** of a so-called bulletin board eating up the spaces )
)If you want to display something without proportional spacing either switch to courier new which is not proportionally spaced.
Code:
Or use the code button on editing
Ask your instructor to explain the 'Standard Closing Angle' technique. If he doesn't know, either ask him to find out or find a new instructor!
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Beagle's SCA is intriguing and, to be honest, more difficult to understand (application is relatively easy).
Alternatively, draw a couple of 10 deg fan lines - one from departure point, the other to arrival point. Once you ascertain your position, use the fan lines to figure how many degrees you are off track so far and how many degrees you are off track to go. Add the two numbers and this is the correction you need to apply to reach destination. Simple, expeditious and no need for a further correction (all the other methods require a second correction when you have regained your original planned track).
Alternatively, draw a couple of 10 deg fan lines - one from departure point, the other to arrival point. Once you ascertain your position, use the fan lines to figure how many degrees you are off track so far and how many degrees you are off track to go. Add the two numbers and this is the correction you need to apply to reach destination. Simple, expeditious and no need for a further correction (all the other methods require a second correction when you have regained your original planned track).
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In the real world, I reckon SCA works best and fastest to get back on track, with minimum thought having to go into it, however to learn 1:60, first practice using double track error questions, then change the 'distance to go' to a shorter distance than the one travelled - the process is the same as DTE, but will get you back earlier.
Daily flying though, Dead reckoning is the reality for VFR flight - 'it's somewhere over there on the other side of that hill - that's where I'm going'
Daily flying though, Dead reckoning is the reality for VFR flight - 'it's somewhere over there on the other side of that hill - that's where I'm going'
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Daily flying though, Dead reckoning is the reality for VFR flight - 'it's somewhere over there on the other side of that hill - that's where I'm going'
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Incidentally, is the above stuff applicable to a UK PPL? I don't recall doing any of this.
In visual nav, the trick is to pick only those waypoints that are clearly unambiguous (e.g. two lakes next to each other, rather than a single lake in an area littered with lakes), fly the computed heading accurately, and monitor progress as one is going along using similarly unambiguous landmarks along the route, and add/subtract say 5 degrees to one's heading if one is drifting off a bit. If the leg length is not excessive, say under 20nm, one can't be far wrong if one actually flies the heading accurately.
I gather that in the JAA CPL, one does all kinds of tricks but I never did the JAA one myself.
In visual nav, the trick is to pick only those waypoints that are clearly unambiguous (e.g. two lakes next to each other, rather than a single lake in an area littered with lakes), fly the computed heading accurately, and monitor progress as one is going along using similarly unambiguous landmarks along the route, and add/subtract say 5 degrees to one's heading if one is drifting off a bit. If the leg length is not excessive, say under 20nm, one can't be far wrong if one actually flies the heading accurately.
I gather that in the JAA CPL, one does all kinds of tricks but I never did the JAA one myself.
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(The dots are to stop this piece of **** of a so-called bulletin board eating up the spaces )
)
If you want to display something without proportional spacing either switch to courier new which is not proportionally spaced.
Web pages are written in HTML.
The spelling of white space is not significant in HTML - one space or a thousand spaces means the same, it's in the definition of the language.
If you want particular spacing, you can either use the non-breaking space entity or one of the tags that overrides normal HTML formatting.
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And in the most practical and simplest of methods in my opinion to use for a JAA ppl or cpl flight test is the: 'Knightson'... A circular transparent piece of plastic with 'wood rings' depicted with the major cardinals dividing the circle into four quarters (A big cross depicted over diminishing equally spaced circles). You plot the actual/forecast wind vector before flight with a "x"; so 090/10kts is 090 from the centre of the Knightson and two rings out from the centre on that radial (each ring representing 5 kts); place the "x" as the new centre of the circle (now skewed) where you are on the map, read off your heading already corrected for wind, add/sub MAG Variation and then you can count the equal distanced wood rings out from where you are to where you want to go to give an accurate ETA measured in minutes. Just make sure you align the depicted cardinals on the Knightson correctly with the map's True North when placing the 'x' over your current position on the map before reading headings etc. No fan lines needed - just wind corrected headings and ETAs measured and a lot less head down time! The size of the Knightson (and subsequently the scale of the circles) is dependent on the average cruise TAS of your aircraft. The Knighston is fixed for its respective TAS. Have used ones respectively for PA28 ppl and PA34 (Seneca) cpl skills tests.
Putting things on plastic doesn't always have to lead to debt
Good luck.
MG
Putting things on plastic doesn't always have to lead to debt
Good luck.
MG
Last edited by mountain-goat; 20th Jul 2009 at 17:43.
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Back in the real world, the real answer that this is a web page.
My opinion of the BB software generally still stands.
And who said thread drift?
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Oops. Learning all the time!
From wiki: Pilotage is frequently combined with navigation techniques such as dead reckoning. When a pilot at a known location cannot see the next visual reference on the route to a destination, he or she can use dead reckoning to get closer to the next reference point. This is the most common form of VFR navigation
I guess that's where my confusion came from, but I had honestly never heard of pilotage - I always just thought - 'if I head south for 20 mins I'll be able to see the mountain, then I'll head for that....' was DR in its entirety
From wiki: Pilotage is frequently combined with navigation techniques such as dead reckoning. When a pilot at a known location cannot see the next visual reference on the route to a destination, he or she can use dead reckoning to get closer to the next reference point. This is the most common form of VFR navigation
I guess that's where my confusion came from, but I had honestly never heard of pilotage - I always just thought - 'if I head south for 20 mins I'll be able to see the mountain, then I'll head for that....' was DR in its entirety