Owner's manual

ABBREVIATIONS AND DEFINITIONS (CONT’D)

NAR Non-Altitude Reporting traffic.

Non-Threat Intruder An aircraft that has entered the TCAS sur-

veillance volume at a distance greater than

6 miles or altitude greater than 1200 feet

above or below your own aircraft.

Pressure Altitude Indicated altitude when barometric pressure

is set to 29.92” Hg. (1013mb). Pressure alti-

tude is used by TCAS to determine the rela-

tive altitude of traffic.

Proximity Intruder An aircraft that is within 6 miles range and

within 1200 feet above or below your own

aircraft but does not meet the TCAS defini-

tion of a threat.

Rad Alt Radio Altitude. Altitude received from a

radio altimeter and used by TCAS to deter-

mine distance to the surface.

RA Resolution Advisory. An audio and visual

indication recommending a vertical maneu-

ver to achieve separation from an intruding

aircraft.

RAs are made up of preventive and correc-

tive maneuvers described in this manual.

RA/VSI Resolution Advisory/Vertical Speed

Indicator. A flight instrument that gives stan-

dard VSI indication plus RA climb and

descend requirements.

Relative Altitude The difference in altitude between two air-

craft.

TCAS calculates relative altitude as the dif-

ference between your own aircraft’s pres-

sure altitude and the encoded pressure alti-

tude of the intruder.

006-08499-0000 Rev 7Effective Date 2/04

Appendix