Figure 3B-147. TA ONLY Operational Situation
The TA-ONLY mode does not identify RA
intruders and will not generate corrective
or preventive RA displays. If an RA threat
level aircraft is present, the display will
show it as a TA target when the TA-ONLY
mode is selected.
j. Corrective RA. Figure 3B-148 shows a
corrective RA display advising immediate action to
provide maximum aircraft separation at CPA. The
indication shows the flight path correction having been
started. Your aircraft is descending through 650 fpm
to exit the vertical speeds indicated by the red arc.
Desired vertical speed is indicated by the green arc,
1500 to 2000 feet per minute, down.
The maneuver is being performed to avoid the
threat traffic indicated by the solid red square. The
traffic is at 1/2 mile and 12 o'clock, 200 feet above
your altitude and level.
At the same time this traffic was upgraded from a
TA to a RA display, the aural alert "Descent, Descent,
Descend" would have been annunciated.
Proximate traffic is also shown on this display.
The solid diamond at 11 o'clock and 3.5 miles is 300
feet above your own altitude and descending. It poses
no present threat, but is within the 6-mile, ±1200 feet
relative altitude range. The other proximate traffic is at
2 o'clock and 4 miles, 500 feet below your altitude and
climbing. It does not pose a present threat.
Two corrective commands may be issued if the
initial corrective command does not provide the
desired aircraft separation. When the threat aircraft
maneuvers in a direction that results in a conflict if
your own aircraft continues with the previously
recommended maneuver these will occur.
An increase advisory, either climb or descend at
2500 fpm to 3000 fpm, will occur if the previous 1500
fpm to 2000 fpm rate of climb or descent is no longer
adequate. This display will be accompanied by an
aural annunciation of, "Increase Climb, Increase
Climb" or "Increase Descent, Increase Descent" as
appropriate for the advisory.
A reversal advisory, a climb advisory after a
descend advisory, or a descend advisory after a climb
advisory will occur if the TCAS determines that the
initial advisory should be reversed. An example of
when this advisory would occur would be when the
intruder causing the initial climb advisory was above
you descending into your aircraft's flight path, then
alerted its flight path to present a new conflict if your
aircraft were to continue to climb.