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6/17/21 

AIM 

2. 

The cockpit equipment functionality required 

by a TIS client aircraft to receive the service consists 
of the following (refer to FIG 4

5

6): 

(a) 

Mode S data link transponder with 

altitude encoder. 

(b) 

Data link applications processor with TIS 

software installed. 

(c) 

Control

display unit. 

(d) 

Optional equipment includes a digital 

heading source to correct display errors caused by 
“crab angle” and turning maneuvers. 

NOTE

 

Some of the above functions will likely be combined into 
single pieces of avionics, such as (a) and (b). 

3. 

To be visible to the TIS client, the intruder 

aircraft must, at a minimum, have an operating 
transponder (Mode A, C or S). All altitude 
information provided by TIS from intruder aircraft is 
derived from Mode C reports, if appropriately 
equipped. 

4. 

TIS will initially be provided by the terminal 

Mode S systems that are paired with ASR

9 digital 

primary radars. These systems are in locations with 
the greatest traffic densities, thus will provide the 
greatest initial benefit. The remaining terminal 
Mode S sensors, which are paired with ASR

7 or 

ASR

8 analog primary radars, will provide TIS 

pending modification or relocation of these sites. See 
FIG 4

5

5, Terminal Mode S Radar Sites, for site 

locations. There is no mechanism in place, such as 
NOTAMs, to provide status update on individual 
radar sites since TIS is a nonessential, supplemental 
information service. 

The FAA also operates en route Mode S radars (not 
illustrated) that rotate once every 12 seconds. These 
sites will require additional development of TIS 
before any possible implementation. There are no 
plans to implement TIS in the en route Mode S radars 
at the present time. 

c.  Capabilities. 

1. 

TIS provides ground

based surveillance 

information over the Mode S data link to properly 
equipped client aircraft to aid in visual acquisition of 
proximate air traffic. The actual avionics capability of 
each installation will vary and the supplemental 
handbook material must be consulted prior to using 

TIS. A maximum of eight (8) intruder aircraft may be 
displayed; if more than eight aircraft match intruder 
parameters, the eight “most significant” intruders are 
uplinked. These “most significant” intruders are 
usually the ones in closest proximity and/or the 
greatest threat to the TIS client. 

2. 

TIS, through the Mode S ground sensor, 

provides the following data on each intruder aircraft: 

(a) 

Relative bearing information in 6

degree 

increments. 

(b) 

Relative range information in 1/8 NM to 

1 NM increments (depending on range). 

(c) 

Relative altitude in 100

foot increments 

(within 1,000 feet) or 500

foot increments (from 

1,000

3,500 feet) if the intruder aircraft has operating 

altitude reporting capability. 

(d) 

Estimated intruder ground track in 

45

degree increments. 

(e) 

Altitude trend data (level within 500 fpm 

or climbing/descending >500 fpm) if the intruder 
aircraft has operating altitude reporting capability. 

(f) 

Intruder priority as either an “traffic 

advisory” or “proximate” intruder. 

3. 

When flying from surveillance coverage of 

one Mode S sensor to another, the transfer of TIS is 
an automatic function of the avionics system and 
requires no action from the pilot. 

4. 

There are a variety of status messages that are 

provided by either the airborne system or ground 
equipment to alert the pilot of high priority intruders 
and data link system status. These messages include 
the following: 

(a)  Alert. 

Identifies a potential collision 

hazard within 34 seconds. This alert may be visual 
and/or audible, such as a flashing display symbol or 
a headset tone. A target is a threat if the time to the 
closest approach in vertical and horizontal coordi-
nates is less than 30 seconds and the closest approach 
is expected to be within 500 feet vertically and 
0.5 nautical miles laterally. 

(b)  TIS Traffic. 

TIS traffic data is displayed. 

(c)  Coasting. 

The TIS display is more than 

6 seconds old. This indicates a missing uplink from 
the ground system. When the TIS display information 
is more than 12 seconds old, the “No Traffic” status 
will be indicated. 

Surveillance Systems 

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