Definition of Cloud

a. Cirrus Detached clouds of delicate and fibrous appearance, without shading, generally white in color and often of silky appearance.

b. Cirrostratus A thin whitish veil which dies not blurs the outline of the sun or moon. This type of cloud often gives rise to halves.

c. Cirrocumulus A corridor layer or patch composed of small white flacks, or very small globular masses without shadows and arranged in groups or lines, but more often in ripples like

d. Altocumulus A layer, or patches composed of lamina or rather flattened globular masses, the smallest elements of the regularly arranged layer being fairly small and thin, with or without shading. The elements may be arranged in groups. The clouds often resembles Cirrocumulus but on a larger scale.

e. Altostratus Striated or fibrous veil, more or less gray or bluish in color. The sun or moon shine through the cloud vaguely, as through ground glass, and may eventually be completely obscured by the cloud. Altostratus is like thick Cirrostratus but does not produce a halo.

f. Nimbostratus A low, amorphous, and rainy layer of dark gray cloud and nearly uniform appearance.

g. Stratus A uniform but usually shallow layer of cloud resembling fog but with its base above the general level.

h. Stratocumulus A layer or patches composed of globular masses or rolls. The smallest of the regularly arranged elements are fairly large, they are soft and gray with darker parts. The cloudlets are often arranged in groups, lines or waves, aligned in one or two directions and the rolls may be as close that their edges join.

i. Cumulus Thick cloud with vertical development, the upper surface is dome-shape while the base is nearly horizontal.

j. Cumulonimbus Thick cloud with develop the thunderstorm, lightning, strong wind and rain which is hazardous to aircraft flying.

a. Danger Area. An airspace of defined dimension within which activities dangerous to the flight of an aircraft may exist at specified time. Aircraft may operate in Danger Area at their own risks.

b. Restricted Area. Airspace of defined dimension, which the flight of an aircraft is restricted in accordance with certain specified conditions. For instances, prior permission may be required 24 hours before the flight take places or the aircraft may be required to contact an ATC unit before entering the area.

c. Prohibited Area. Airspace of defined dimension within which the flight of an aircraft is forbidden or not allowed at all times. Examples are over a palace, place of worship, army camp etc.

For the purpose of Aviation, The international Civil Aviation Organization (ICAO) has divided the world into 8 regions as far as aviation concerned as follows:-

a. Middle East & South East Asia
b. Pacific
c. Caribbean
d. Africa
e. North America
f. South America
g. North Atlantic
h. Europe

The airspace within each of these regions has been further sub-divided into FIRs (Flight Information Region) where it has been determined that air traffic services will be provided in particular portion of the airspace or at particular airfields.

The Flight Information Region is an airspace of defined dimensions within which flight information service and alerting service is provided. The country accepting responsibility for providing air traffic services within this region of airspace shall do so in accordance with existing ICAO standards and practices.

The countries concerned in these regions shall name the authority responsibility for providing air traffic services.

Once an FIR has been designated, the state responsible for air traffic services must establish a Flight Information Centre (FIC) to provide Flight Information Service (FIS) and alerting service within this region. Usually this centre is located with an air traffic control unit.

The circuit patterns for both fix-wing and helicopter are generally the same except for direction and height. A fixed wing circuit is higher than that of helicopters.

UPWIND

The upwind leg begins at the point where the airplane leaves the ground. It continues climbing straight ahead to gain the sufficient altitude before the 90-degree left turn is made to the crosswind leg.

CROSSWIND

The crosswind leg is a flight path at a 90° angle to the takeoff direction. After making a left turn from the upwind leg one enters the crosswind leg. This turn is made at a safe height, while the climb is continued towards the indicated or cleared circuit altitude.

DOWNWIND

The downwind leg is a flight path parallel to the landing runway in the opposite of the landing direction with the runway at the left side of the aircraft.

BASE LEG

The base leg is a flight path at a 90° angle to the landing runway direction and connects the downwind leg to the final approach leg.

FINAL

The final approach leg is a flight path in the direction of landing from the base leg to the runway.

Air Traffic Control (ATC) is a service provided by ground based controllers who direct aircraft. The primary purpose of ATC is to separate aircraft to prevent collisions either aircraft on ground or in the air, to organize and expedite the flow of traffic and to provide information and other support for aircrews when able. Prevent collisions is refered to as separations, which is a term to prevent aircraft for coming too close to each other by use of lateral, vertical and longitudinal separation minima.

ATC is also provide additional services such as providing information to aircrews, weather and navigation information and NOTAMs (Notice to Airmen).