air navigation The basic principles of air navigation are identical to general navigation, which includes the process of planning, recording, and controlling the movement of a craft from one place to another. Successful air navigation involves piloting an air ...

, the 1 in 60 rule is a

rule of thumb In English, the phrase ''rule of thumb'' refers to an approximate method for doing something, based on practical experience rather than theory. This usage of the phrase can be traced back to the 17th century and has been associated with various t ...

which states that if a pilot has travelled sixty miles then an error in track of one mile is approximately a 1° error in heading, and proportionately more for larger errors. The rule is used by pilots with many other tasks to perform, often in a basic aircraft without the aid of an

autopilot An autopilot is a system used to control the path of an aircraft, marine craft or spacecraft without requiring constant manual control by a human operator. Autopilots do not replace human operators. Instead, the autopilot assists the operator' ...

, who need a simple process that can be performed in their heads. This rule is also used by

air traffic controller Air traffic control specialists, abbreviated ATCS, are personnel responsible for the safe, orderly, and expeditious flow of air traffic in the global air traffic control system. Usually stationed in air traffic control centers and control ...

s to quickly determine how much to turn an aircraft for separation purposes. The rule is based on the

small-angle approximation The small-angle approximations can be used to approximate the values of the main trigonometric functions, provided that the angle in question is small and is measured in radians: : \begin \sin \theta &\approx \theta \\ \cos \theta &\approx 1 - \ ...

(which states that, for small angles,

sin In a religious context, sin is a transgression against divine law. Each culture has its own interpretation of what it means to commit a sin. While sins are generally considered actions, any thought, word, or act considered immoral, selfish, s ...

''θ'' ≈ ''θ'', where ''θ'' is in

radian The radian, denoted by the symbol rad, is the unit of angle in the International System of Units (SI) and is the standard unit of angular measure used in many areas of mathematics. The unit was formerly an SI supplementary unit (before that c ...

s), along with the fact that one radian (which is about 57.3°) is close to 60°. In reality a 1 mile in 60 error is 0.96°, and the rule becomes increasingly inaccurate for larger errors. But since even a skilled pilot cannot manually fly with better than about 2° accuracy, and winds are constantly varying, the rule remains useful for most realistic situations. This rule of thumb is incredibly powerful in the aviation environment. It states that for each degree off (or displacement) over a distance of 60

nautical mile A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as the meridian arc length corresponding to one minute ( of a degree) of latitude. Today ...

s (NM), it will result in 1 NM off course. It can be applied in various areas of interest when flying, and is easily remembered. This proves to be valuable in many different scenarios, en route navigation, approach, and even on vertical profiles. The math behind this shows that this method is not entirely accurate, with roughly a 5% error, but the rule's objective is to get workable numbers in a dynamic environment, and it fits this purpose quite well. Here is the breakdown: A circle of 60 NM radius has a circumference of: :2 x 60 x π = 376.99 NM 376.99 divided by 360° produces: :376.99/360 = 1.047 NM (off by 4.7%) This rule is therefore very good approximation. As a coincidence, 1 NM is about 6,000 feet (6,076.1 feet) so we can use the 60:1 rule for this too. For a 1 degree shift at 1 NM, there are about 100 feet of offset. This becomes very useful for estimating or correcting vertical speed settings and flight path angles (FPA) during climb, descent, or approaches. If a gradient in % is required, the numbers work out with the same rule: :1% over 1 NM ≈ 60' It is also useful to find out the lateral deviation from a given

VOR VOR or vor may refer to: Organizations * Vale of Rheidol Railway in Wales * Voice of Russia, a radio broadcaster * Volvo Ocean Race, a yacht race Science, technology and medicine * VHF omnidirectional range, a radio navigation aid used in a ...

course or radial: Each dot on a VOR indicator represents 2° of deviation, or 200' per dot per DME. There are other applications to this rule. One such application is time drift. An hour is equal to 60 minutes, and a minute is equal to 60 seconds, so some other relationships between angle and time can be observed.

Examples

If a pilot is flying a leg of 120 miles and finds after traveling 60 miles that he is two miles to the right of track, then a correction of 4° to the left (2° to fly parallel to the intended track and another 2° to bring him to his target) will bring him to his destination. If a pilot is flying a 120-mile leg and finds after 30 miles that he is two miles left of track, then he has flown 4° left of his intended track, i.e. :2 × 60/30 left of track. Changing the heading four degrees right will now bring him to parallel the intended track. At that point he still has 90 miles to his next waypoint. He is thus two miles to the left of that and thus the waypoint is 4/3 of a degree (2 × 60/90) to the right, or approximately 1° right. The pilot then adds these two to get 5° and flies 5° right of his previous heading. One can also use the 1 in 60 rule to approximate distance from a

, by flying 90 degrees to a radial and timing how long it takes to fly 10 degrees (the limit of the

course deviation indicator A course deviation indicator (CDI) is an avionics instrument used in aircraft navigation to determine an aircraft's lateral position in relation to a course to or from a radio navigation beacon. If the location of the aircraft is to the left of th ...

). The time in seconds divided by 10 is roughly equal to the time in minutes from the station, at the current

ground speed Ground speed is the horizontal speed of an aircraft relative to the Earth’s surface. It is vital for accurate navigation that the pilot has an estimate of the ground speed that will be achieved during each leg of a flight. An aircraft diving ve ...

References

Recreational Flying Enroute
* Taylor, Richard L., ''Fair Weather Flying'', MacMillan 1981, p. 193, * Mike Roumens, "M3: The Mile, The Mach, The Minute, Mental Math For Aviators", pages 2–5, Copyright 2013, {{ISBN, 1484846427 * https://www.cnatra.navy.mil/ebrief/documents/01_Training_Air_Wing_One/references/COLUMN%204/INST%20REFERENCES/60-1%20rules%20Jan%2007.pdf Air navigation Rules of thumb