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1 Dec 2003
34-45-4
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MAINTENANCE MANUAL
CAS-100 COLLISION AVOIDANCE SYSTEM
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These two conditions cause a Traffic Advisories (TAs) problem:
1. TCAS calculates that at the current closure rate and distance, the time separating
own aircraft and intruder aircraft is less than TA Alarm Time
AND
the altitude difference between own aircraft and intruder aircraft is less than the TA
Relative Altitude Threshold.
2. The separation in slant range between own aircraft and intruder aircraft is less than
minimum TA Protection Volume.
These two conditions cause Resolution Advisories (RAs) to be issued:
1. TCAS calculates that at the current closure rate and distance, the time separating
own aircraft and intruder aircraft is less than RA Alarm Time.
AND
the altitude difference between own aircraft and intruder aircraft is less than the RA
Relative Altitude Threshold.
2. The separation in slant range between own aircraft and intruder aircraft is less than
minimum RA Protection Volume.
Determining if the Resolution Advisory is Corrective or Preventive:
The resolution advisory is corrective if the altitude difference between own aircraft and
the intruder aircraft is less than the Corrective RA Relative Altitude Threshold.
Typical Resolution Advisory and Traffic Advisory Volumes for Sensitivity Levels
Figure 3 (Sheet 2 of 2)
