4 Operating Procedures
4.1 TCAS
Rev. No. Rev. Date Page No.
ATR72-500
SUPPLEMENTARY
OPERATIONS MANUAL
1 30 Sep 2010 2
Original Date Issued: 17 March 2010
4.1.2.2 Resolution Advisory
A. The Resolution advisory is an appropriate vertical avoidance maneuver. The RA
display is incorporated into the vertical speed indicator RA/ VSI. By illuminating red
and green areas around the dial it displays the required rate, or limitation of climb
or descent to avoid a possible collision.
B. Some of the typical Resolution Advisories, which are shown on the RA/ VSI, will
require a maneuver by the crew while others will warm against maneuvering.
C. Resolution advisories are grouped as Corrective advisories or preventive
advisories. Corrective Advisories require a positive action by the crew
accompanied by a green arc on the RA/ VSI showing Fly To guidance. Preventive
Advisories require that NO action be taken to alter the flight path of the aircraft.
Symbol used: + <<CORRECTIVE ACTION TO DO>>
D. With the resolution advisory, the TCAS triggers an aural synthesized voice alert
describing the avoidance maneuver required at the same time.
RESOLUTION
ADVISORY
DOWNWARD UPWARD
VERTICAL SPEED
REQUIRED (VS)
INITIAL PREVENTIVE
RA
Monitor vertical speed Monitor vertical speed 0
CORRECTIVE RA Descent, descent Climb, climb Monitor
ANY
STRENGTHENING OF
AN RA
Increase descent,
Increase descent
Increase climb,
increase climb
+/ - 2500 ft/min
ANY WEAKENING OR
SOFTENING OF AN
RA
Adjust vertical speed,
Adjust
Adjust vertical speed,
Adjust
+/ - 1500 ft/min
OPPOSITE RA Descent, descent
NOW
Climb, climb NOW Adjust
CROSSOVER RA Descend, crossing,
descend, descend,
crossing, descend
Climb, crossing climb,
climb, crossing climb
+/ - 2500 ft/min
MAINTAIN EXISTING
VERTICAL SPEED RA
Maintain vertical Speed,
Maintain
Maintain vertical
Speed, Maintain
+/ - 1500 ft/min
MAINTAIN EXISTING
VERTICAL SPEED
WHILE CROSSING
THREATS ALTITUDE
Maintain vertical
Speed, crossing
maintain
Maintain vertical
Speed, crossing
maintain
Maintain
+/ - 4400 ft/min
> Vs > +/ -
1500 ft/min
VERTICAL SPEED
RESTRICTED
Adjust vertical speed,
Adjust
Adjust vertical speed,
Adjust
Adjust
END OF RA Clear of conflict 0
UNCONTROLLED
CD COPY