On behalf of Megatron, I'm posting the a pic of the TCAS II used
in the B747-400 aircraft. Unlike the TCAS I. the TCAS II provides
pitch commands to the pilot.
Traffic Advisory (TA): TAs are given to the pilot
in form of the word TRAFFIC displayed in yellow on the ND, and the
aural voice annunciation "traffic, traffic". This is not the
highest alert level. Its purpose is first to call attention to a
possible conflict.
TCAS triggers a TA as soon as an intruder enters the TA specific
DMOD or tau area. If bearing information is available, the intruder
can be identified on the ND by a yellow, solid circle. Otherwise,
the circle is removed and lateral distance and relative altitude
with vertical motion arrow (if motion is detected) is displayed in
yellow numbers under the word TRAFFIC.
Resolution Advisory (RA): The highest alert level.
Its purpose is to resolve a conflict by providing the pilot with
aural and visual pitch commands. The pilot has to disengage the
autopilot immediately as the escape maneouver has to be flown
manually. Flight director commands as well as ATC advisories have
to be ignored. The pitch command of an RA has always the highest
priority.
TCAS triggers an RA when a target enters the RA specific DMOD or
tau area. If no altitude data is available from the target, an RA
will not occur.
If bearing information is available, the intruder can be identified
on the ND by a red, solid square. Otherwise, the square is removed
and lateral distance and relative altitude with vertical motion
arrow (if motion is detected) is displayed in red numbers under the
word TRAFFIC.
Other Traffic: Its a TCAS term for targets
detected within a range of 40 to 7 NM from the own aircraft and --
if the target sends altitude information -- within 2700 and 1201
feet relative altitude. These targets are represented on the ND as
outlined white diamonds. They do not represent an alarm.
Proximate Traffic: Its a TCAS term for targets
detected within a range of 6 NM from the own aircraft and -- if the
target sends altitude information -- within 1200 feet relative
altitude. These targets are represented on the ND as solid white
diamonds. They do not represent an alarm.
More info here http://www.aerowinx.de/html/tcas.html
