Instructor User Guide
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13 Oct 2017
Page 255
16.4.1.1.3.6 Reversal Resolution Advisory (Single Threat) Perform Above
FL210
Scenario Specifics:
• TCAS generates an RA requiring the crew to climb or descent to avoid conflict.
• Number of intruders specified in this scenario is 1.
• Own aircraft V/S recommended max limit +/-1000 fpm.
In this scenario, the crew is required to perform a reversal climb/descent maneuver
following the initial RA/maneuver in order to clear the conflict due to a maneuver
done by the intruder.
The scenario starts with the intruder approaching from the location selected in the
Horizontal Position pane and at the same level as the own aircraft.
The path of the intruder is continuously re-computed to mirror that of the own aircraft
until the first resolution advisory is issued by the own aircraft.
As the TCAS detects that the intruder does not dis-engage (in other words, it is still
approaching the own a/c at the same level), the own a/c will issue a second RA (this
is the reversal RA).
As the own a/c tries to maneuver to avoid conflict after the reversal RA, the intruder
dis-engages (i.e, stops mirroring the actions of the own a/c) and follows its own
trajectory at that point.
For example at FL150, during the scenario:
• TCAS will issue a TA advisory "TRAFFIC TRAFFIC" approximately at 45
sec, at which time the intruder meets the TA range test and TA altitude test.
• Subsequently, TCAS will issue a RA advisory "CLIMB CLIMB" or
"DESCEND DESCEND" at approximately 30 sec, at which time it meets the
RA range test ant RA altitude test.
• TCAS will issue a RA reverse advisory such as “DESCEND, DESCEND
NOW" or "CLIMB, CLIMB NOW" at approximately 20 sec before the CPA.
The success of this scenario requires that the flight crew’s response to resolution
advisory is rapid and smooth.
Note: It should be noted that while the acceleration response to the initial RA is
approximately 0.25g, the acceleration response to the reversal RA is
approximately 0.35g.
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