INTERNATIONAL STANDARDS
AND RECOMMENDED PRACTICES
CHAPTER 1. DEFINITIONS
When the following terms are used in the Standards and
Recommended Practices concerning the units of measurement
to be used in all aspects of international civil aviation air and
ground operations, they have the following meanings:
Ampere (A). The ampere is that constant electric current
which, if maintained in two straight parallel conductors of
infinite length, of negligible circular cross-section, and
placed 1 metre apart in vacuum, would produce between
these conductors a force equal to 2 x 1 Om7 newton per metre
of length.
Becquerel (Bq). The activity of a radionuclide having one
spontaneous nuclear transition per second.
Candela (cd). The luminous intensity, in the perpendicular
direction, of a surface of l/600 000 square metre of black
body at the temperature of freezing platinum under a
pressure of 101 325 newtons per square metre.
Celsius temperature (PC). The Celsius temperature is equal to
the difference t°C = T - Tu between two thermodynamic
temperatures T and To where To equals 273.15 kelvin.
Coulomb (C). The quantity of electricity transported in
1 second by a current of 1 ampere.
Degree Celsius (“C). The special name for the unit kelvin for
use in stating values of Celsius temperature.
Farad (F). The capacitance of a capacitor between the plates
of which there appears a difference of potential of 1 volt
when it is charged by a quantity of electricity equal to
1 coulomb.
Foot cft). The length equal to 0.304 8 metre exactly.
Gray (Gy). The energy imparted by ionizing radiation to a
mass of matter corresponding to 1 joule per kilogram.
Henry (H). The inductance of a closed circuit in which an
electromotive force of 1 volt is produced when the electric
current in the circuit varies uniformly at a rate of 1 ampere
per second.
Hertz (Hz). The frequency of a periodic phenomenon of which
the period is 1 second.
ANNEX 5
Human performance. Human capabilities and limitations
which have an impact on the safety and efficiency of
aeronautical operations.
Joule (J). The work done when the point of application of a
force of 1 newton is displaced a distance of 1 metre in the
direction of the force.
Kelvin (K). A unit of thermodynamic temperature which is the
fraction l/273.16 of the thermodynamic temperature of the
triple point of water.
K&gram (kg). The unit of mass equal to the mass of the
international prototype of the kilogram.
Knot (kt). The speed equal to 1 nautical mile per hour.
Litre (L). A unit of volume restricted to the measurement of
liquids and gases which is equal to 1 cubic decimetre.
Lumen (Im). The luminous flux emitted in a solid angle of
1 steradian by a point source having a uniform intensity
of 1 candela.
Lux (Lr). The illuminance produced by a luminous flux of
1 lumen uniformly distributed over a surface of 1 square
metre.
Metre (m). The distance travelled by light in a vacuum during
II299 792 458
of a second.
Mole (mol). The amount of substance of a system which
contains as many elementary entities as there are atoms in
0.012 kilogram of carbon-12.
Note.- When the mole is used, the elementary entities must
be specified and may be atoms, molecules, ions, electrons,
other particles or specified groups
of
such particles.
Nautical mile (NM). The length equal to 1 852 metres exactly.
Newton (N). The force which when applied to a body having
a mass of 1 kilogram gives it an acceleration of 1 metre per
second squared.
Ohm (G). The electric resistance between two points of a
conductor when a constant difference of potential of 1 volt,
applied between these two points, produces in this
1
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