1:60 rule

[mikehallam]

I radian is 57.3 degrees i.e. nearly 60.
[A radian is an arc of radius R to the length R round a circle's circumference.
Near enough to a chord.

Or think of an equilateral triangle, i.e. equal sides and equal (60) degrees each inside corner.

It's simplified calc. as one of many ad hoc tools for sensibly assessing & correcting a course when map reading.

Mike Hallam.

[Gertrude the Wombat]

"Pure DR" is where you don't look out of the window at all (or, there's nothing to look at, eg over an ocean) until you get to your destination. If you look out of the window from time to time and correct your course depending on what you see that's cheating, the pilot is applying brain power to overcome the limitations of DR!

[homeguard]

The 1:60

Whilst it may be fashionable to denounce anything that requires thought and structure as a futile waste of effort; the infringements of controlled airspace, danger areas and Red Arrows displays continue and from reports are getting worse. Sadly and most important pilots also become lost and spatially disorientated flying into all sorts of things, the results of which can become tragic.

Whether some of you like it or not structured navigation training is crucial for the basis of by whatever means you navigate. There are of course many ways to skin a cat and just as many navigation techniques. That doesn’t matter; the important thing is that a methodical structure is taught. GPS is based logically using Radians, i.e. 1:60 and Descartes grid, so the pilot should have a basic understanding of the use of the rule just the same when using a GPS and should it fail.

Use of the 1:60 as a working base to navigation is perhaps the simplest available. The number 60, as said, is a rounded up Radian. The actual definition of a Radian is; that its angle subtends the length of arc. To see this; draw a circle and from the centre of the circle draw two lines 60 degrees apart. Between the two points that each line crosses the circumference take a measurement. Compare this measurement to the length of each line (radius). You will discover that the length of the arc is almost the same as the length of each of the two lines. I say almost because the circumference is of course an arc, a curving line. Reduce to angles of less than 20 degrees and discover that the difference between the arc and the straight line is impossible to measure on a standard chart. Incidentally 20 degrees is one third that of 60 so therefore the distance off track would be one third off the distance gone.

Treat one radius line as the intended track and the other as the track made good. At a point 24 miles along the intended track take a measurement between the two tracks and divide the distance gone by the distance apart which we will say equals 2 miles.. E.g. 24 miles flown is divided by 2 miles off track which equals a ratio of 12. Divide the radian 60 by the ratio 12 = 5. You are 5 degrees off track. The1:60 formulae commonly given in the text books is to divide distance off by distance gone and multiply by 60 (2\24x60 = 4.999). You may also divide the degrees off track into 60 to find the distance in miles that you are off track. 60\5 = 12 therefore 24\12 = 2 miles off track.

The simplest way is to pre-determine the points along the track where you will assess your progress known as a ‘pinpoint’ or ‘mid track fix’ which doesn’t have to be half way or quarter way, and draw 5 or 10 degree fan lines abeam the point – no need for any sums other than to double or treble the track error as appropriate to regain track. You will regain track should you double the error in exactly the same time and distance or by trebling the error in half the distance and time. You will now have a point and an ETA to regain track.

The 1:60 allows for velocity as well simple angles. Your aircraft is flying at 100kts with a wind 90 degrees across at 20kts. 100\20=5 therefore 60\5 = 12, your drift is 12 degrees. All sorts of navigation problems can be understood by understanding Radians, the 1:60 rule.

[ExSp33db1rd]

Buy a handheld GPS.

or .... draw lines at 10 deg either side of track starting from the start and back from the destination. Fan lines someone has called them earlier.

When you have fixed your position as being halfway between your desired track and the 10 deg line you have drawn from the start point, that is 5 deg off track, but the same point might only be 1/3 of the way between your track line and the 10 deg line from the destination, call that 3 deg.

If you only turn 5 deg toward track you will only parallel, but if you add the 5 and the 3 and turn 8 deg. towards track - Bingo ! Works for any distance along track, not much maths involved.

If I knew how to post diagrams to PPRuNe I'd show you.

The real trick is not to try to do a maths exam in a rattling steel cabinet, big numbers, commonsense

( Oh! and buy that GPS ! )

Used to navigate 707's with a sextant, recently flew a microlight into controlled airspace, needed a second bearing to make my report to ATC, couldn't be bothered re-programming the panel mounted GPS, pulled a handheld from my pocket - had to laugh, sextants in 707's, now 2 GPS's in a microlight !!

Use the KISS method. Keep It Simple, Stupid.

[KandiFloss]

Hi all,

Thanks for everyone's tips and advice! I've just put my brain back together after it just exploded after trying to get my head round some of techniques.

Thank you ExSp33db1rd (and anyone else who gave a simple version) for a nice simple version! Will go away and try working with that as some of the other techniques are just too cranial for me

[ExSp33db1rd]

Pilot Chick

When learning to navigate BIG aeroplanes, an old navigator ( tho' younger then than I am now ! ) once told me to pretend to be sat on the tail of the aeroplane and to just steer it across the map.

Of course you have to consider wind-drift and magnetic variation, but don't get bogged down with science.

One had a trainee co-pilot try to steer me 310 deg. from Singapore to Australia ( think about it ! ) he had done the maths and got it wrong, and totally forgot The Big Picture.

Pass your exams - then buy a GPS ! Shouldn't say that, but GPS's are OK if you first know the basics of navigation, if one removes some of the mental gymastics, and allows you more time to keep your eyes out of the cockpit - why not.

Some people enjoy the challenge of really accurate navigation, and it is fun to see how science works, but don't lose sight of what you are trying to do, have fun, get where you are going, and don't fly into mountains, other aircraft, or prohibited airspace !

Good luck

[Bigglesthefrog]

Hmmmm.... I will bet you a pound to a pinch of Pig muck that all those that have put forward an explanation for the 1 in 60 rule completely forget about it when they are navigating their aeroplanes across good old blighty. Unless you have a dedicated navigator sitting beside you that you can trust to do all the sums associated with this, I would do what I suspect 99% of pilots on here that use a chart do, and that is follow the china graph line that you drew on the half million when you planned the flight. We don’t live in the desert; we live in a land with lots of recognisable towns, motorways, railways and many other landmarks. Granted, we also have the occasional bit of bad visibility too, but if you can’t see the ground properly you should still be sitting on it!
In my view, you draw the track line on the map and then you draw on the wind vector. You do your calculation on what heading to fly and check this out regularly from the moment you take off with landmarks as you go along the track. If you are a bit to the right of the line, then steer a bit more to the left and check things again in a few minutes making more alterations if it is necessary.
Navigating like this with “Mk1 Eyeball” ensures that you get an accurate appreciation of where you are AND affords the important requirement of LOOKING OUT OF THE WINDOW!
I bet another pinch of Pig muck that the same guys I referred to at the beginning of my statement have a nice little GPS perched somewhere on the panel and Why not indeed? Because a GPS backed up with a current aviation chart provide a great navigation setup that is accurate, easy to use and takes most of the worry out of the operation allowing one to enjoy the flying.
1 in 60 rule…… straight into the waste paper basket would be my advice

[vee-tail-1]

My pennyworth. How often is the standard liquid filled compass commonly fitted to GA aircraft telling the truth? It is usually overeading, underreading, oscillating, or going round in circles. If it does stay still long enough to make an in flight correction to the DI you then have the problem that most DIs have an unknown rate of precession.
GPS and chart works for me.

[stickandrudderman]

I'm with Bigglesthefrog!

[GearDownFlaps]

apart from the atpls, RA60D , never understood it never used it and thus far never suffered as a result of this

[ExSp33db1rd]

....... and go IFR. ( I Follow Roads - or railway lines )

( Not sure that Pilot Chick really wants to know, but maybe needs to know for her exams? )

[KandiFloss]

ExSpeedBird: IFR - I follow Roads ... I like that!

It's a bit embarrasing to admit this but I do actually have a PPL, it's just that i've never got my head around the 1:60 rule. I just think that I should try to understand it now that i've clocked up the grand total of 79 hours Dual and 20 hours PIC - hey! I guess that must be a decimal fraction of your flying time?!

GearDownFlaps: I'm glad that you said "never understood it never used it and thus far never suffered as a result of this" it helps me to admit this too . As they say in 'help' groups ... "Thanks for sharing"

[Tinstaafl]

I've flown thousands of hours using 1:60. Not just across desert, farmland, bush, towns or wherever but also for tasks such as finding the height of a weather radar return, finding a lead bearing for starting a turn to intercept a radial/localiser beam, determining maximum drift for a known or estimated crosswind component etc.

Pretty much anytime you need to convert an angle to or from a cartesian coordinate that involves our hexigesimal time or angle systems.

Off track corrections can be done in your head to an acceptable level of accuracy. You only need remember '1, 2, 3, 4 & 1 and a half' and when to use those numbers. It's a three step problem: First to stop diverging from track any more, second to fly towards track, and third to maintain track again.

Step 1: Find the angle of the divergence from track (Track Error or TE) to use to adjust heading to stop any more drift.
Step 2: Find the angle needed adjust heading to close towards track, regaining track at some chosen point (Closing Angle)

Adjust heading by both those amounts ie Track Error and Closing Angle, and then:

Step 3: Remove the closing angle so you maintain the track you just regained.

Step 1: Track Error

If you find yourself off track and have flown any distance that is something like 60nm (say 55nm to 75nm or so) then multiply the distance off track by '1'. For example, flown 55 miles since last on track and fix your position 3 miles off track then multiply the distance off by '1' to find the angle by which you diverged away from the desired track. In this case 3 degrees. If you alter heading by 3 degrees towards track you will parallel track.

If you have flown somewhere around 30 nm use '2' eg flown 34 nm and find yourself 4 nm off track: 2 x 4 equates to 8 deg drift. Alter heading 8 deg towards track to parallel track.

Flown around 20 nm? Use '3 times' eg Flown 19 nm and are 2 nm off track? 3 x 2 equates to 6 deg Track Error. Alter heading 6 deg towards track to parallel.

Flown around 15 nm? Use '4 times'. 16 nm flown since last on track and 1 nm off track? 1 x 4 = 4 deg off track.

If the distance flown is about 45 nm then use 1 1/2 ie 1 x the distance off track + another half of that eg flown 42 nm and 4 nm off track: 1 x 4 = 4 degrees + an extra 'half' of that figure. 2 in this case so Track Error = 6 deg.

Step 2: Closing Angle

Choose a point where you would like to be back on track again. It could be the destination, next turning point or even just some feature that is easy to find.

Use the same method as for Step 1, but use the distance from your present position to the chosen point on track. For example, the point where you would like to regain track is 35nm away and you're 4nm off track. 2 x 4 gives 8 deg needed to alter heading to close track.

Adjust heading towards track by the amounts you just worked out in Steps 1 & 2.

Step 3: Maintain Track

Later, when back on track, adjust heading to remove the Closing Angle found in Step 2 eg Track Error was 6 deg, Closing Angle 8 deg gave total heading adjustment to get back on track of 14 deg. Now that you're back on track turn towards your original heading my 8 deg. That leaves you with your original heading corrected by the Track Error only.

Using the method requires only a few measurements : Distance Run since last on track, Distance to go to get to the back on track position, and distance off track, and only takes moments to do. It's usually possible to see ahead of time where you will fix your position off track so those measurements and even the calcuation can be done ahead of time so when you fly over the off-track fix all you need do is turn towards track by the calculated amount and log the time.

Further, the Distance Run & Distance to Go you measure can then be used to find your groundspeed and revised estimate for the destination/on track fix, killing two tasks with one set of distance measurements.

[ExSp33db1rd]

and don't forget to watch your height, apply a bit of carb/ heat, re-set the D.I., avoid cloud, keep away from that restricted area, change radio frequency, give your pax. a sick bag, tell the youngest in the back seat to shut up whilst you listen to the ATIS etc. etc.

Buy a GPS - 2 if you are worried about one failing at the most inopportune moment - as it will one day.

[Tinstaafl]

If that sort of workload balancing is too much then I'd have to think either incompetence, or the need for a licence limited to either mandatory
GPS equipment or flight with a co-pilot, flight engineer, navigator, radio operator & a flight attendant

It's just not that hard to measure 3 distances on a 1:1,000,000 or 1:500,000 or 1:250,000 scale chart and note the time & next HDG at a pinpoint or fix. Christ, I even manage to do it with my calibrated thumb & a pencil without drama. Everything else can be done looking out the window.

[ExSp33db1rd]

Preferably all of the above !

Flying my single seat microlight around NZ, it's a real hardship not getting that first cup of coffee 30 secs after lift off. ( or the Brake Dwell Cocktail after landing - but that's a secret - and my lips are sealed ! )

Read my post #26. It's Horses for Courses, put me in front of an FMS or a Glass Cockpit and I wouldn't have a clue ( at least, not much ) I don't even answer a Text message on my cellphone - too hard, but if the methods you are happy with, work for you, no problem, but if I were Pilot Chick I'd have run off screaming under the nearest passing bus by now !

I was told that I'd never make a navigator as long as I had a Hole in my A**** until I'd been over Berlin with the shells coming through the cockpit whilst I was trying to get a 3-wind drift fix with the Drift Sight. I never had to.

I watched my own Nav. students in despair sometimes, trying to cope with Sight Reduction tables and the St. Hilaire method of working out an Astro fix with a sextant - then came along INS and now GPS, and they've never had to.

Of course one must understand the basics before playing with the toys, but after that, whatever works for you, and I repeat - KISS ( Keep It Simple, Stupid )

Recently flying the microlight, I needed a cross bearing, rather than re-programme the panel mounted GPS, I pulled a handheld GPS from my pocket, I guess I could have used ' the-length-of-the-ball-point-pen-cap-equals-20 miles-and-I-can-guess-around-150-deg-relative-bearing ' method, but it was just easier.

QED

[BluntM8]

PilotChick,

If it helps, I have to think of the one in sixty in terms of dumper-trucks (don't ask why...). I know that if I go sixty dumper trucks along, and one to the side, I've made a degree. From that I can work backwards for lesser distances. 15 dumper trucks along and already one sideways? Must be 4 degrees!

I'm now a navigator on Tornado GR4....

Draw your own conclusion!

Blunty

[Dashtrash]

Pilotchick,

I'll see if i can explain this without trying to draw it. hmmmmm

1:60 was beyond me for most of my flying training. I only learned this method when I started working as an instructor for a lovely old guy who I think had entries of W.Wright in his logbook....I digress.

Take each leg of your plan on the chart. Draw 10degree splay lines on either side from start and finnish points of the leg (point A-B). What you'll end up with is a line if diamond shapes along your route. (diamonds are a chicks best friend). Apply common sense here and don't try it on short 10nm legs.

What these diamonds provide you with is a scale to make accurate guesses.

Now, picture yourself inlfight. You fix your position a little off track. With the 10degree lines you can quite accurately estimate your track error (from A) and correction angle (to B). Add the two together and alter your heading by that much.

It takes a little bit of extra time in the pre flight stage but you will be more confident about flying longer, more direct and accurate VFR legs.

The only catch is that you MUST maintain your heading. You can't apply a correction to a heading (with any method) if you've havn't maintained one to begin with.

Hope that helps. Feel free to PM if you need any help deciphering all of this.
Happy flying

[mikehallam]

Problem with lots of lines drawn on the chart extra to the route (and a few circles round danger spots) is that it clutters it up. The classic chinagraph lines are fat & obscure bits too.

If one is off course, and over ground features where reading them to chart is feasible, just change course a bit to corrrect. It really doesn't matter what angle, but gently is more efficient.

If you're, say, flying 5 degrees off track & persist with this, all other things being equal, you will be 5 miles off to one side in 60 miles. And pro rata.

So unless you're following a badly mistaken course plot, you're never going to be too far off if correlating features regularly crop up.

Now if it's another thing altogether when featureless terrain/water is crossed !

[Crash one]

Originally Posted by Pull what

The 1 in 60 rule is excellent over areas without visual navigational features, water, desert, unpopulated areas

[QUOTE-mikehallam]Now if it's another thing altogether when featureless terrain/water is crossed ! [/QUOTE]

Could you please explain how the 1-60 rule is of any use over water/featureless terrain?