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a) No termination date has yet been established for use of nautical mile
and knot. For planning purposes any termination date for these units
will not be before 31 December 1990.
b) No termination date has yet been established for use of the foot.
ANNEX 5
ATTACHMENT B. GUIDANCE ON THE APPLICATION OF THE SI
1. Introduction 1.3 The supplementary units of the SI are listed in Table
B-2 and may be regarded either as base units or as derived
1.1 The International System of Units is a complete, units.
coherent system which includes three classes of units:
a) base units;
b) supplementary units; and
Table B-2. SI supplementary units
C) derived units. Quantity Unit Symbol
1.2 The SI is based on seven units which are dimen- plane angle
sionally independent and are listed in Table B-1.
solid angle
radian rad
steradian sr
Table B-1. SI base units
Quantity Unit Symbol
1.4 Derived units of the SI are formed by combining base
units, supplementary units and other derived units according
amount of a substance mole mol to the algebraic relations linking the corresponding quantities.
electric current ampere A The symbols for derived units are obtained by means of the
mathematical signs for multiplication, division and the use of
length metre m exponents. Those derived SI units which have special names
luminous intensity candela cd and symbols are listed in Table B-3.
mass kilogram kg
thermodynamic temperature kelvin K Note.- The specific application of the derived units listed
time second s in Table B-3 and other units common to international civil
aviation operations is given in Table 3-4.
Table B-3. SI derived units with special names
Quantity Unit Symbol Derivation
absorbed dose (radiation) gray GY J/kg
activity of radionuclides becquerel Bq I/s
capacitance farad F C/V
conductance siemens S A/V
dose equivalent (radiation) sievert Sv J/kg
electric potential, potential difference, electromotive force volt V W/A
electric resistance ohm R V/A
energy, work, quantity of heat joule J N.m
force newton N kg. m/s2
frequency (of a periodic phenomenon) hertz Hz I/s
illuminance lux Ix Im/m2
inductance henry H Wb/A
luminous flux lumen Im cd.sr
magnetic flux weber Wb V.s
magnetic flux density tesla T Wb/m2
power, radiant flux watt W J/s
pressure, stress pascal Pa N/m2
quantity of electricity, electric charge coulomb C A.s
ANNEX 5 19 No 15
19/11/87
Annex 5 - Units of Measurement to be used iri Air
and Ground Ope~tions Attachment B
1.5 The SI is a rationalized selection of units from the
metric system which individually are not new. The great
advantage of SI is that there is only one unit for each physical
quantity - the metre for length, kilogram (instead of gram)
for mass, second for time, etc. From these elemental or base
units, units for all other mechanical quantities are derived.
These derived units are defined by simple relationships such as
velocity equals rate of change of distance, acceleration equals
rate of change of velocity, force is the product of mass and
acceleration, work or energy is the product of force and
distance, power is work done per unit time, etc. Some of these
units have only generic names such as metre per second for
velocity; others have special names such as newton (N) for
force, joule (J) for work or energy, watt (W) for power. The
SI units for force, energy and power are the same regardless
of whether the process is mechanical, electrical, chemical or
nuclear. A force of 1 newton applied for a distance of 1 metre
can produce 1 joule of heat, which is identical with what
1 watt of electric power can produce in 1 second.
1.6 Corresponding to the advantages of S1, which result
from the use of a unique unit for each physical quantity, are
the advantages which result from the use of a unique and welldefined
set of symbols and abbreviations. Such symbols and
abbreviations eliminate the confusion that can arise from
current practices in different disciplines such as the use of "b"
for both the bar (a unit of pressure) and barn (a unit of area).
1.7 Another advantage of S1 is its retention of the
decimal relation between multiples and sub-multiples of the
base units for each physical quantity. Prefixes are established
for designating multiple and sub-multiple units from "exa"
(10'8) down to "atto" (10-18) for convenience in writing and
speaking.
1.8 Another major advantage of SI is its coherence. Units
might be chosen arbitrarily, but making an independent choice
of a unit for each category of mutually comparable quantities
　
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