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ACAS X MOPS
§220.127.116.11.2.1.5 and in §18.104.22.168.2.1.6, even if a portion of the information is masked by the
edge of the active display area.
On shared displays (see §22.214.171.124.2.7), the off scale symbology described in this paragraph
shall (1528) be used unless the symbology is inconsistent with that used for other
functions of the shared display. In these cases, a message of either “TRAFFIC OFF-
SCALE”, “OFFSCALE”, or “OFF-SCALE” shall (1529) be used. These messages shall
(1530) be written in the colors specified in §126.96.36.199.2.1.3 which correspond to the traffic's
188.8.131.52.2.1.5 Altitude Data Tag
A data tag shall (1531) indicate the relative altitude, if available, of the intruder aircraft
and shall (1532) consist of two digits indicating the altitude difference in hundreds of
feet. For an intruder above ownship, the tag shall (1533) be placed above the traffic
symbol and preceded by a “+” sign; for one below ownship, the tag shall (1534) be
placed below the traffic symbol and preceded by a “-” sign.
Note: It is recommended that the “+” or “-” character be emphasized by using a
slightly larger character set than that used for the digits.
The tag for co-altitude traffic shall (1535) be displayed as the digits “00”. The “00”
characters should be placed above the symbol if the intruder aircraft closed from above;
below the symbol if the intruder aircraft closed from below. If no trend information is
available, the co-altitude “00” symbol should be placed below the traffic symbol.
The color of the data tag shall (1536) be the same as the symbol.
The display shall (1537) be capable of displaying relative altitudes of up to a maximum
of ±9900 feet.
As an option, the data tag may indicate the intruder's reported altitude instead of the
relative altitude between the two aircraft. If this option is implemented, a switch shall
(1538) be provided to permit a pilot to select this type of altitude data tag. If the actual
altitude is to be shown on a continuous basis after selection by the flight crew, it shall
(1539) be corrected for the local barometric pressure using the same correction used by
the flight crew. If the actual altitude is not corrected for the local barometric pressure, the
display of this type of data tag shall (1540) be limited to a maximum of 30 seconds if the
ownship is below 18,000 feet (FL180) before it automatically reverts back to the display
of relative altitude. When the display of the actual altitude is selected, it shall (1541) be
clearly annunciated on the traffic display. If implemented, the actual altitude shall
(1542) be displayed as a three digit number representing hundreds of feet, MSL. For
example, 007 represents 700 feet MSL and 250 represents 25,000 feet MSL (FL250).
Actual altitude tags shall (1543) be positioned above or below the traffic symbol in a
manner consistent with the relative altitude data tags. As with the display of relative
altitude, the display shall (1544) be capable of displaying tracked traffic up to a
maximum of ±9900 feet of the ownship.
184.108.40.206.2.1.6 Intruder Vertical Speed Arrow
A vertical arrow shall (1545) be placed to the immediate right of the traffic symbol if the
vertical speed of the intruder (as determined by the ACAS X tracker) is equal to or
greater than 500 fpm, with the arrow pointing up for climbing traffic and down for
descending traffic. The color of the arrow shall (1546) be the same as the traffic symbol.
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