ZAON PCAS XRX - Example 2: Prioritizing

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UNDERSTANDING PCAS28
Example 2: Prioritizing
If another aircraft is added to
create this scenario, the first
thought might be the new,
“closer” aircraft might be the
greatest threat, and thus be
priority 1. But upon further study,
notice the aircraft is 500 feet
below, whereas the other aircraft
is only 300 feet above.
XRX prioritizes based on altitude
first, but does take into consider-
ation the ascent/descent rate, as
shown in the next scenario, as
well as range in certain circum-
stances. However, the obvious
notion that accidents only occur
at your altitude holds true, and
the aircraft with the least amount
of vertical separation will take
priority over others.
RELATIVE ALTITUDE
RANGE
2600’
2400’
2200’
2000’
1800’
1600’
1400’
2.0 NM 1.0 NM 0 NM 1.0 NM 2.0 NM
RANGE
DIRECTION
0.5 NM
1.0 NM
1.5 NM
2.0 NM
2.5 NM
XRX
PRIMARY AIRCRAFT
PRIMARY AIRCRAFT
XRX
SECONDARY AIRCRAFT
RANGE
RANGE
RELATIVE ALTITUDE
SECONDARY AIRCRAFT