4.20 Ground effect is a phenomenon of increase of a lift force and reduction of
inductive resistance of a wing approaching a surface. The extent of this phenomenon
depends on the design of the craft but generally occurs at an altitude less than the
mean chord length of the wing.
Maximum vertical extent of ground effect hge for an actual craft
is determined experimentally or by calculations proceeding from a condition:
4.21 Length (L) means the overall length of the underwater watertight envelope of
the rigid hull, excluding appendages, at or below the design waterline in the
displacement mode with no lift or propulsion machinery active.
4.22 Lightweight is the displacement of the craft in tonnes without cargo, fuel,
lubricating oil, ballast water and fresh water in tanks, consumable stores, passengers
and crew and their effects.
4.23 Machinery spaces are spaces containing internal combustion engines with an
aggregate total power output of more than 110 kW, generators, oil fuel units, propulsion
machinery, major electrical machinery and similar spaces and trunks to such spaces.
4.24 Maximum operational weight means the overall weight up to which operation in
the intended mode is permitted by the Administration.
4.25 Maximum speed is the speed achieved through the air at the maximum
continuous propulsion power for which the craft is certified at maximum operational
weight.
4.26 Muster station is an area where passengers can be gathered in the event of
an emergency, given instructions and prepared to abandon the craft, if necessary. The
passenger spaces may serve as muster stations if all passengers can be instructed there
and prepared to abandon the craft.
4.27 Oil fuel unit is the equipment used for the preparation of oil fuel for
delivery to equipment used for the preparation for delivery of heated oil to an internal
combustion engine, and includes any oil pressure pumps, filters and heaters dealing with
oil at a pressure of more than 0.18 N/mm2.
4.28 Open vehicle spaces are spaces:
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.1 to which any passengers carried have access;
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.2 intended for carriage of motor vehicles with fuel in their tanks for their own
propulsion; and
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.3 either open at both ends or open at one end and provided with adequate natural
ventilation effective over their entire length through permanent openings in the
side plating or deckhead or from above.
4.29 Operating compartment means the enclosed area from which the navigation and
control of the craft is exercised.
4.30 Operating station means a confined area of the operating compartment
equipped with necessary means for navigation, manoeuvring and communication, and from
where the functions of navigating, manoeuvring, communication, commanding, conning and
lookout are carried out.
4.31 Operational speed is the normal operating speed at reduced level of
propulsion power in ground effect mode.
4.32 Organization means the International Maritime Organization.
4.33 Passenger is every person other than:
4.34 Passenger craft is a craft which carries more than twelve passengers.
4.35 Place of refuge is any naturally or artificially sheltered area which may be
used as a shelter by a craft under conditions likely to endanger its safety.
4.36 Public spaces are those spaces allocated for the passengers and include main
seating areas, lavatories and similar permanently enclosed spaces allocated for
passengers.
4.37 Service spaces are those enclosed spaces used for pantries containing food
warming equipment but no cooking facilities with exposed heating surfaces, lockers,
storerooms and enclosed baggage rooms.
4.38 Skeg is a vertical or inclined profiled plate or a volumetric construction,
which forms part of or is attached to a wing for the purpose of decreasing the inductive
aerodynamic resistance or increasing the effectiveness of static or dynamic air
cushions. When operating up to the ground effect mode it can be also used for sliding on
the water or other surface and for providing stability.
4.39 Special category spaces are those enclosed spaces intended for the carriage
of motor vehicles with fuel in their tanks for their own propulsion, into and from which
such vehicles can be driven and to which passengers have access for embarking and
disembarking, including spaces intended for the carriage of cargo vehicles.
4.40 Static air cushion means a high-pressure region generated by directing air
from the propulsion engine or other engine underneath the craft's body and/or wings.
4.41 System Safety Assessment (SSA) means a systematic, comprehensive evaluation
of the implemented systems to establish safety objectives and to show that the relevant
safety requirements are met. The method is described in part C.
4.42 Unassisted craft is any passenger WIG craft other than an assisted craft,
which machinery and safety systems arranged such that, in the event of damage disabling
any essential machinery and safety systems in any one compartment, the craft retains the
capability to navigate safely.
4.43 Worst intended conditions means the specified environmental conditions
within which the intended operation of the craft is provided for in the certification of
the craft. This should take into account parameters such as the worst conditions of wind
force allowable, wave height (including unfavourable combinations of length and
direction of waves), minimum air temperature, visibility and depth of water for safe
operation and such other parameters as the Administration may require in considering the
type of craft in the area of operation.
4.44 WIG craft is a multimodal craft which, in its main operational mode, flies
by using ground effect above the water or some other surface, without constant contact
with such a surface and supported in the air, mainly, by an aerodynamic lift generated
on a wing (wings), hull, or their parts, which are intended to utilize the ground effect
action.
4.45 WIG craft are categorized according to the following types:
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.1 type A: a craft which is certified for operation only in ground effect. Within
prescribed operational limitations, the structure and/or the equipment of such a
craft should exclude any technical possibility to exceed the flight altitude over
the maximum vertical extent of ground effect, as defined in 4.20;
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.2 type B: a craft which is certified for main operation in ground effect and to
temporarily increase its altitude outside ground effect to a limited height, but
not exceeding 150 m above the surface, in case of emergency and for overcoming
obstacles; and
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.3 type C: a craft which is certified for the same operation as type B; and also
for limited operation at altitude exceeding 150 m above the surface, in case of
emergency and for overcoming obstacles.
4.46 WIG craft operational modes:
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.1 Amphibian mode is the special operational mode of amphibian WIG craft
over the surface other than water, when at rest or in motion its weight is fully
or predominantly supported by appropriate combination of forces of static and
dynamic air cushion and/or by vertical forces produced on the hull or other
devices due to their contact with such a surface and/or due to sliding on it;
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.2 Displacement mode means the regime, whether at rest or in motion, where
the weight of the craft is fully or predominantly supported by hydrostatic forces;
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.3 Transitional mode denotes the transient mode from the displacement mode
to the planing mode (or amphibian mode) and vice versa;
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.4 Planing mode denotes the mode of steady state operation of a craft on
water surface by which the craft's weight is supported mainly by hydro-dynamic
forces;
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.5 Take off/landing mode denotes the transient mode from the planing mode
(or amphibian mode) to the ground effect mode and vice versa;
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.6 Ground effect mode is the main steady state operational mode of flying
the WIG craft in ground effect above water or other surface;
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.7 Fly-over mode denotes increase of the flying altitude for WIG craft of
types B and C within a limited period, which exceeds the vertical extent of the
ground effect but does not exceed the minimal safe altitude for an aircraft
prescribed by ICAO provisions; and
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.8 Aircraft mode denotes the flight of a WIG craft of type C above the
minimal safe altitude for an aircraft prescribed by ICAO regulations.
4.47 Wing denotes an air foil or other air lift generating surface to support the
weight of the craft in flight and may include the fuselage.