ADF (Automatic Direction Finder)

ADF (Automatic Direction Finder) is the
radio signals in the low to medium
frequency band of 190 Khz. to 1750
Khz. It was widely used today. It has
the major advantage over VOR
navigation in the reception is not limited to line of sight distance. The
ADF signals follow the curvature of the
earth. The maximum of distance is
depend on the power of the beacon.
The ADF can receives on both AM radio
station and NDB (Non-Directional Beacon). Commercial AM radio stations
broadcast on 540 to 1620 Khz. Non-
Directional Beacon operate in the
frequency band of 190 to 535 Khz.

Aircraft External Lighting System

The external lights on aircraft fall into two general categories. The first is navigation lights or beacons that are always illuminated while the aircraft is in operation. A second type includes takeoff and landing lights that are used to improve visibility when the plane is close to or on the ground. Several of these lights are discussed in greater detail below.

► Navigation lights: All aircraft are equipped with a steady light near the leading edge of each wingtip. When facing forward from the perspective of the pilot, the light on the right wingtip is green while that on the left wing is red. The different colors make it possible for an outside observer, such as the pilot of another aircraft, to determine which direction the plane is flying. These navigation lights are most useful at night when it is more difficult to tell the direction the plane is going without them.

Aviation Turbine Fuel (ATF)

Aviation Turbine Fuel (ATF) is dispensed from specially designed refuellers, which are driven up to parked airplanes and helicopters. Major airports have hydrant refuelling systems that pump the fuel right up to the filling outlets on the tarmac through underground pipelines for faster refuelling. Essentially, ATF is pumped into an aircraft by two methods: Overwing and Underwing. Overwing fuelling is used on smaller planes, helicopters, and piston-engine aircraft and is similar to automobile fuelling - one or more fuel ports are opened and fuel is pumped in with a conventional pump.

Air Traffic Control (ATC)

Air traffic control (ATC) is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC
systems worldwide is to separate
aircraft to prevent collisions, to
organize and expedite the flow of
traffic, and to provide information and other support for pilots when able.
Preventing collisions is referred to as separation, which is a term used to prevent aircraft from coming too close
to each other by use of lateral, vertical
and longitudinal separation minima;
many aircraft now have collision avoidance systems installed to act as a backup to ATC observation and
instructions. In addition to its primary
function, the ATC can provide
additional services such as providing
information to pilots, weather and
navigation information and NOTAMs (NOtices To AirMen). In many countries, ATC services are
provided throughout the majority of
airspace, and its services are available
to all users (private, military, and
commercial).

Auxiliary Power Unit (APU)

An auxiliary power unit (APU) is a device on a vehicle that provides
energy for functions other than
propulsion. They are commonly found
on large aircraft, as well as some large
land vehicles.
The primary purpose of an aircraft APU
is to provide power to start the main
engines. Turbine engines must be accelerated to a high rotational speed
in order to provide sufficient air
compression for self-sustaining
operation. Smaller jet engines are
usually started by an electric motor,
while larger engines are usually started by an air turbine motor. Before
engines are to be turned, the APU is
started, generally by a battery or hydraulic accumulator. Once the APU is running, it provides power (electric, pneumatic, or hydraulic, depending on the design) to start the aircraft's
main engines.

VERY HIGH FREQUENCY OMNI-RANGE

VOR (VHF Omni-Range) is the basic
Electronic navigation that in use
today . This VHF Omni-Range
navigation method relies on the
ground based transmitters which
emitted signals to VOR receiver. The VOR system operates in the VHF
frequency band , from 108.0 to
117.95 MHz. The reception of VHF
signals is a line of sight situation . You
must be on the minimum altitude of
1000 feet (AGL) above ground level in order to pick up an Omni signals
service range.

OPERATION
The VOR facility at ground base
transmits two signals at the same time.
One signal is constant in all directions
as a reference phase. Another signal, it
is variable-phase signal and it rotates
through 360 degrees, like the beam from the lighthouse. Both signals are
in phase when the variable signal
passes 360 degrees (reference to
magnetic north) and they are 180
degrees out of phase when the
rotating signal passes 180 degrees The aircraft equipment receives both
signals. The receiver will calculate the
difference between the two signals,
and interprets the result as a radial
from the station to pilots on the
aircraft.
RADIALS: The two signals from VOR
transmitter generate 360 lines like
spokes in a wheel . Each line is called a Radial . VOR navigation equipment on the airplane will determine which of
those 360 radials the airplane is on.

Black Box (FDR)

The flight data recorder (FDR) is designed to record the operating data
from the plane's systems. There are
sensors that are wired from various
areas on the plane to the flight-data
acquisition unit, which is wired to the
FDR. When a switch is turned on or off, that operation is recorded by the FDR
In the United States, the Federal Aviation Administration (FAA) requires that commercial airlines record a
minimum of 11 to 29 parameters,
depending on the size of the aircraft.
Magnetic-tape recorders have the
potential to record up to 100
parameters. Solid-state FDRs can record more than 700 parameters. On
July 17, 1997, the FAA issued a Code
of Federal Regulations that requires
the recording of at least 88 parameters
on aircraft manufactured after August
19, 2002. Here are a few of the parameters
recorded by most FDRs:
• Time Pressure
• Altitude
• Airspeed
• Vertical acceleration
• Magnetic heading
• Control-column position
• Rudder-pedal position
• Control-wheel position
• Horizontal stabilizer
• Fuel flow

Solid-state recorders can track more
parameters than magnetic tape
because they allow for a faster data
flow. Solid-state FDRs can store up to
25 hours of flight data. Each additional
parameter that is recorded by the FDR gives investigators one more clue
about the cause of an accident.

Pitot Static System In Aircraft

Pitot static system , device for
measuring the rate at which a fluid
flows. Among the principal
applications of the device are an
airspeed indicator for aircraft and a
distance and speed indicator for ships. The device contains a short tube with
one open end that faces directly
toward the stream of air or other fluid.
When no fluid is moving into the
opening, a minimum pressure, called
the static pressure, is exerted against it. When a stream is flowing into it, the
pressure rises by an amount that
depends on the velocity of the stream.
Behind this tube is another tube with a
number of small vents at right angles
to the direction of the first tube. When a stream raises the pressure against
the opening of the first tube, the
pressure against the vents is still equal
to the static pressure. A suitable gauge
compares these pressures, using the
static pressure as a reference, and gives a reading in units of velocity. For
an aircraft this reading is called
"indicated airspeed" ; "true airspeed"
requires a correction, made
automatically by some airspeed
indicators, for the local density of the air. Because of winds, neither reading
accurately measures the speed in
relation to a point on the surface of the
earth. That value is known as
groundspeed. Although airspeed is
normally given in knots or miles per hour, for supersonic aircraft it may be
given in Mach numbers, which give the
ratio of the aircraft's speed to the
speed of sound. For navigational
purposes Mach numbers are
converted to true airspeed.