1. AIR NAVIGATION
Part 5
The 1 in 60 Rule

2. Introduction In modern aircraft it is often necessary
to do quick mental calculations
to check that the navigational computer
is still making sense
and that we have not fallen into the
garbage in - garbage out trap.
We have looked at progress along track
(DST and ETA);
we now need to consider
our position across track.

3. Tracks Track Required The Track Required is normally
the line drawn on the map
between the departure airfield
and the destination,
or from one turning point
to another on the route.
Track Required

4. Tracks A Pinpoint If for some reason the aircraft drifts off track
and we can establish
our position using some
unique feature (a pinpoint),
Pinpoint
Track Required

5. Tracks Track Made Good If for some reason
the aircraft drifts off track
and we can establish
our position using some
unique feature (a pinpoint),
then the line joining the
departure airfield and
the pinpoint is known as
the Track Made Good (TMG).
Track Made Good
Pinpoint
Track Required

6. Tracks Revised Track From a pinpoint, which is off the track required,
we have 2 options.
One would be to regain
the required track,
but more normally we would
draw a line from the pinpoint
to the next turning point.
This is called the Revised Track.
Track Made Good
Pinpoint
Revised Track
Track Required

7. Tracks Definitions Track Required The planned route. Track Made Good
The line joining the
departure airfield and
the pinpoint
Revised Track
A line from the pinpoint
to the next turning point.
Track Made Good
Pinpoint
Revised Track
Track Required

8. The 1 in 60 Rule The 1 in 60 rule states: If an aircraft flies
a Track Made Good
1º in error from
the Track Required,
then after 60 miles of flying
the aircraft will be one mile
off the Track Required.
Track Made Good
Track Required

9. This can be proved with trigonometry . . . .
The 1 in 60 Rule
This can be proved with trigonometry
but all we need to know is how to use the triangle.
After 60 nm the error is
1 nm for every 1° off track
For Example
Track Error of 1°
1 nm
Track Required
60 nm

10. The 1 in 60 Rule For Example After 60 nm the error is
1 nm for every 1° off track
For Example
Track Error of 10°
10 nm
Track Required
60 nm

11. The 1 in 60 Rule For Example After 60 nm the error is
1 nm for every 1° off track
For Example
Track Error of 15°
15 nm
Track Required
60 nm

12. The 1 in 60 Rule For Example After 60 nm the error is
1 nm for every 1° off track
For Example
Track Error of 10°
20 nm
Track Required
120 nm

13. The 1 in 60 Rule For Example After 60 nm the error is
1 nm for every 1° off track
For Example
Track Error of 15°
30 nm
Track Required
120 nm

14. The 1 in 60 Rule The 1 in 60 rule holds good
for track errors up to 23º
beyond that
the difference in length of the two tracks
(Track Made Good (TMG) and Track Required)
becomes too great
and the approximation will not work.

15. The 1 in 60 Rule The simplest application of the 1 in 60 rule
is when a pinpoint is taken exactly
halfway along a track.
The triangle as the aircraft drifts off track
is exactly mirrored by the triangle showing
the aircraft regaining track.
Pinpoint
Track Error
Closing Angle
Revised Track
Track Required A B

16. The 1 in 60 Rule by twice the track error
As the triangles are the same size and shape,
it is only necessary to alter heading to the right
by twice the track error
to ensure the aircraft reaches point B.
As the pinpoint is taken halfway along track,
the actual distances do not affect the results.
Pinpoint
Track Error
Closing Angle
20°
Revised Track
10°
10°
Track Required A B

17. The 1 in 60 Rule Once you understand the method
and can do the mental arithmetic,
you can omit the drawing of the triangles.
Because pinpoints are not always available
when we want them,
we are often left with awkward numbers
that do not lend themselves to mental arithmetic.
The solution is to use approximate numbers
that are easily handled,
either round numbers like 20, 30, 40
or those divisible by 6.
Pinpoint
Track Error
Closing Angle
20°
Revised Track
10°
10°
Track Required A B

18. Check Understanding Track revised Track required Track made good
What is a line on a map between
the departure airfield and the destination
known as?
Track revised
Track required
Track made good
Heading required

19. Check Understanding What is meant by the term Track Made Good?
A line joining the pinpoint
to the next turning point
A line joining the departure airfield
and the destination
A line joining the departure airfield
and the pinpoint
A line joining the next turning point
to the destination

20. Check Understanding Revised Track Required Track Renewed Track
What is a line from the pinpoint
to the next turning point called?
Revised Track
Required Track
Renewed Track
Track Made Good

21. Check Understanding 6 6° 12 degrees 9 degrees 6 degrees 3 degrees
At the fix point,
an aircraft is 6 nm off track,
What is the required closing angle? 6
Track error 6°
12 degrees 60
9 degrees
6 degrees
3 degrees

22. an aircraft is 3 nm off track.
Check Understanding
After 20 nm of flight,
an aircraft is 3 nm off track.
What is the track error? 60
2 degrees
Track error 9
6 degrees 3 9° 20
9 degrees 60
10 degrees

23. Check Understanding 3 9 2 6 3 2 If an aircraft flies for 90 nm
with a track error of 2o
how many miles off track will it be? 9 60
Track error 3 2 6 2° 90 3 2

24. Check Understanding a. 4° b. 8° c. 16° d. 24°
An aircraft flying from A to B is found to be
off track at the pinpoint shown below.
The pilot calculates the track error as 8°.
By how much does the pilot need to turn
to reach point B?
As the triangles are the same size and shape,
it is only necessary to alter heading to the right
by twice the track error
Pinpoint
TMG A B 8°
a. 4°
b. 8°
c. 16°
d. 24°

25. AIR NAVIGATION
End of Presentation