Systems Guide

Aerosoft
Airbus A320/A321
SYSTEMS
Systems guide
Vol
4
04-03-60
28 October 2014
An ILS is autotuned when the departure runway has a ILS (during PREFLIGHT AND TAKE OFF mode) and when the
F-PLN approach mode has an ILS in all other modes.
SEATBELT/NO SMOKING
The no smoking signs should be left ON during all operational flights. The seatbelt sign behavior is semi-
automated when in AUTO and the seatbelts sign will be lit when the aircraft is below 10,000 feet. Any time the
indication for the passengers changes a chime is played in the cabin.
WEATHER RADAR
The Collins WXR (weather radar) detects precipitations by means of a high frequency radar. The radar beam
reflects of rain drops or hail and is received by the system. The radar returns are then displayed in a calibrated
gain color system. When the radar beam hits the ground (or other solid objects) it is also returned. The Collins
WXR is able to eliminate ground clutter to provide a clearer image. However the Ground Mapping option does
allow the user to scan the ground and pick up coastlines and other important ground features.
The fully automated multiscan mode sets the gain and tilt automatic to the ideal settings for each stage of the
flight, reducing pilot workload. Multiscan operates the weather radar as a highly experienced would do manual.
The pilot is advised to keep in mind that at the cold top of
clouds the water is mostly in ice crystals and super cooled
water. These so not reflect the radar very effectively.
Scanning a cloud from top to bottom using the manual scan
will reflect that as reflections will increase near the bottom
of the cloud where all the precipitation is in the form of
liquid water and the density of droplets highest.
As radar beams travel in a straight line the curvature of the
earth is important. Low clouds can be invisible at a distance
because they are hidden by the curvature of the surface
even though they are in range. In multiscan mode the radar
is able to skim the radar horizon (tilting the beam so it
remains just above the horizon). Keep in mind that over a
distance of 320 NM the curvature of the earth causes the
earth’s surface to move down approximately 65,000 feet. So
if the aircraft is at 25,000 feet the earth’s surface is about
90,000 feet below the aircraft 320 NM in front of the
aircraft. The antenna is stabilized up a 45 degree bank,
meaning the radar sweep will be level with the horizon up to 45 degrees. It is also stabilized for pitch.
AUTO MULTISCAN MODE
In auto mode (MULTISCAN switch set to AUTO) the tilt is automatically controlled. Two beams (upper and lower)
are merged together to become one picture representing weather in the possible vertical flight path of aircraft.
Also in MULTISCAN AUTO mode the GCS (ground clutter suspension) is usually in AUTO mode and so the ground
clutter will be suppressed. Only when GCS switch is set to spring loaded OFF-Position the ground clutter would be
visible but GCS is also only available in MULTISCAN AUTO mode, not in MAN mode!
MAN MULTISCAN MODE