Do people use the 1 in 60 rule?

[scallaghan]

Hi

Do many people use the 1 in 60 rule for DR navigation?

For example either for a diversion along with the ruler or perhaps a track correction?

When I was training I use to use a double and half rule to get me back onto track when I went off instead of 1 in 60.

Cheers

:D

[High Wing Drifter]

An alternative is to turn towards track by 40deg(90kts) or 30deg(120kts) and then fly on that correction for 1 min for every mile you are off track to get back on track. Then add 10secs to your ETA for for each of those minutes.

[Gerard123]

Hmmmmmm......shouldn't be off course in the first place :p

1 in 60 is useful learn it and use it ! remember GPS batteries are the enemy you'll always need good basic nav skills :ok:

[767bill]

Hi Scallaghan,

I've been struggling with this one ever since I was taught it for my first nav exercises. Then my instructor told me to draw 10 degree slanting lines (just intercepts) at the 1/4, 1/2 way and 3/4 points. So if at the 1/4 way point you are 10 degrees off you correct by tracking error 10 degrees and half that again = 15 (TE + 1/2), if half way when you correct then TE X 2, if 1/3 way TE + 1/3. If more or less than 10 degrees out you extrapolate and estimate the TE.

Personally I think this is easier than the pure 1 in 60 calculation - too much like mental arithmetic in the air (God forbid...though you could use your slide rule/ nav computer...). What I like about the above method is that its very visual and with the interceps on the chart you should know by the 3/4 point if it's worked.

Interested to hear any comments.

[scallaghan]

Hi 767 Bill


Basically what I have been doing is the double and half rule that I was taught or to use the 1 in 60.

That was to use those 10 degree fan lines on my chart.

If I was ever off track which has happened :D I would see if I am either 5 or 10 degress lets say within those fan lines.

Double that figure and then half it when I get back onto track.

So if I had a track of 300 and was off track by 5 degrees port, double this to 10 degrees and add to make it 310. Followed by half to 305 when I get back on track at the next way point.

[BigGrecian]

1 in 60 = oh what fun basis of quite a bit of military nav.

[Tinstaafl]

I use 1:60 all the time. Not just for off-track corrections either. Lead distances/angles for DME arc turns onto final, if Wx radar equipped it can be used to derive altitudes for radar returns (not necessary in those new-fangled 3D type radars) etc etc. Pretty much anytime I need to convert an angle to distance or vica versa.

[Astra driver]

I find I use the 1:60 for all the things tinstaafl mentioned, especially for estimating radar return heights (100ft per nm per degree) plus I find it handy for quickly estimating initial crosswind corrections on instrument approaches:
1/2 a degree for each knot of crosswind component at typical 120 knot groundspeeds
(or 1/3 degree at 180, etc)

[GRIFFIN2000]

The rule is also very fine to use to calculate TOD on an ARC...

[Jagbag]

Pretty much every flying day!

[BankAngle50]

Currently on the 737-800 and use it all the time. Very useful to work out trk miles on an arc to an ILS ect...

[Ian_Wannabe]

Hey guys - Now ive always stated on here that I suck at maths, and this shows with the simplest calculations such as the 1:60 rule.

Can someone put it in the simplest terms in the world for me? I got this question wrong on my nav written exam, and I read it through over and over in the Thoms but I instantly forget it, which makes me think I never fully got it in the first place.

I dont know why I struggle with this calculation so much - but I do.... anyone got a simpletons way of putting it? :confused:

Thanksly muchly :ok:

[BEagle]

I use a version of the 1 in 60 termed the Standard Closing Angle method:

If you realise that you are a miles off track and wish to fly b miles back on to track, then you need to turn through an angle ö whose sine is equal to a/b. Now the 1 in 60 rule tells us that ö is more or less equal to (a/b)x60 and if you fly your distance b at v miles per minute for t minutes, then ö = (60/v)x(a/t). If a and t are made numerically the same, that is you fly for the same number of minutes as your number of miles off track, then a = t and a Standard Closing Angle ö of (60/v) can be used where v is expressed in miles per minute. Hence the SCA at 360 kts is 10°, at 120 kts it is 30° and at 90 kts the SCA is 40°.

With a SCA of 40 deg, along track velocity v cos ö is 0.766 v or roughly 3/4 of the original velocity; hence what would have taken 3 minutes now takes 4. The ETA should therefore be delayed by 1/3 of the time spent flying at the SCA.

It's so easy that many dyed-in-the-wool FIs won't trust it!

How far off track? 3 miles
Turn towards by 40 deg.
Fly for 3 minutes towards track and note that ETA at the end of the leg will be + 1 minute
Return to original heading, re-check DI synchronisation and slip ball.

[High Wing Drifter]

Beagle,

Same method as wot I said above. I just didn't know what to call it :8

Ian,

I dont know why I struggle with this calculation so much - but I do.... anyone got a simpletons way of putting it?
I think of it as:

For the track error angle: Miles Off / Miles Gone * 60 or as I remeber it 60/Gone * Off. My Menomic is GoneOff

For the closing angle: Miles Off / Miles To Go * 60, or as I remeber it 60/Go * Off. My menomic is GoOff.

Correction = GoneOff+GoOff.