Owner’s Manual | PCAS XRX
STRENGTHS AND LIMITATIONS 35
Visually Identifying Aircraft
Please be aware of what you can and can’t visually identify. Many pilots will experience a situation where the unit will
show an aircraft and attempts to visually identify it are unsuccessful. The following is a short list of visual impairments
to consider:
> Even to a well-trained eye, general aircraft beyond 1 5 to 2 miles away are too small to see
> Visual effects, such as ground clutter, optical myopia, and haze can obscure aircraft
> Only a relatively small “slice” of the 360° area around the cockpit is within the pilot’s scan. Aircraft above, below,
and behind may be blocked by your aircraft and much more difficult to see.
> Aircraft at or about your same altitude tend to appear 200 feet lower for every half mile of distance between you
and the aircraft. This is an optical illusion which is caused by the curvature of the earth (the horizon) combined
with your aircraft angle of attack.
Recognition & Reaction Time
The importance of early
warning cannot be stressed
enough when it comes to
detecting a potential
threatening aircraft. These
charts indicate how
combined aircraft speed
and distance play a role in
determining your reaction
time.
According to the FAA, a
typical response time is 12 5
seconds. This translates to a
one- to three-mile
minimum response
distance from an incoming
aircraft. PCAS will help you
increase awareness and
response time.
The data presented is from
FAA AC 90-48C.
Seconds to Impact
Range 600 MPH* 360 MPH*
10 miles 60 secs. 100 secs.
6 miles 36 secs. 60 secs.
5 miles 30 secs. 50 secs.
4 miles 24 secs. 40 secs.
3 miles 18 secs. 30 secs.
2 miles 12 secs. 20 secs.
1 mile 6 secs. 10 secs.
0 5 mile 3 secs. 5 secs.
Table F: Time to Closest Approach Point (CAP)
*Combined A/C speeds. BOLD times mark when insufficient time remains to alter course.
Running time Action Seconds
00:00 See object 0.1
00:00 Recognize aircraft 1.0
00:01 Become aware of collision course 5.0
00:06 Decision to turn left or right 4.0
00:10 Muscular reaction 0.4
00:10 Aircraft lag time 2.0
00:12 TOTAL TIME 12.5
Table E: Recognition & Reaction Time
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