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direct result of a TIS-B target being displayed in the
2. While TIS-B is a useful aid to visual traffic
avoidance, its inherent system limitations must be
understood to ensure proper use.
(a) A pilot may receive an intermittent TIS-B
target of themselves, typically when maneuvering
(e.g., climbing turns) due to the radar not tracking
the aircraft as quickly as ADS-B.
(b) The ADS-B-to-radar association pro-
cess within the ground system may at times have
difficulty correlating an ADS-B report with
corresponding radar returns from the same aircraft.
When this happens the pilot may see duplicate traffic
symbols (i.e., "TIS-B shadows") on the cockpit
(c) Updates of TIS-B traffic reports will
occur less often than ADS-B traffic updates. TIS-B
position updates will occur approximately once
every 3-13 seconds depending on the type of radar
system in use within the coverage area. In
comparison, the update rate for ADS-B is nominally
once per second.
(d) The TIS-B system only uplinks data
pertaining to transponder-equipped aircraft. Aircraft
without a transponder will not be displayed as TIS-B
(e) There is no indication provided when any
aircraft is operating inside or outside the TIS-B
service volume, therefore it is difficult to know if one
is receiving uplinked TIS-B traffic information.
3. Pilots and operators are reminded that the
airborne equipment that displays TIS-B targets is for
pilot situational awareness only and is not approved
as a collision avoidance tool. Unless there is an
imminent emergency requiring immediate action,
any deviation from an air traffic control clearance in
response to perceived converging traffic appearing
on a TIS-B display must be approved by the
controlling ATC facility before commencing the
maneuver, except as permitted under certain
conditions in 14CFR §91.123. Uncoordinated
deviations may place an aircraft in close proximity to
other aircraft under ATC control not seen on the
airborne equipment and may result in a pilot
deviation or other incident.
e. Reports of TIS-B Malfunctions.
Users of TIS-B can provide valuable assistance in the
correction of malfunctions by reporting instances of
undesirable system performance. Since TIS-B
performance is monitored by maintenance personnel
rather than ATC, report malfunctions to the nearest
Flight Service Station (FSS) facility by radio or
telephone. Reporters should identify:
1. Condition observed.
2. Date and time of observation.
3. Altitude and location of observation.
4. Type and call sign of the aircraft.
5. Type and software version of avionics
4-5-9. Flight Information Service-
FIS-B is a ground broadcast service provided
through the ADS-B Services network over the
978 MHz UAT data link. The FAA FIS-B system
provides pilots and flight crews of properly equipped
aircraft with a cockpit display of certain aviation
weather and aeronautical information. FIS-B recep-
tion is line-of-sight within the service volume of the
ground infrastructure. (See FIG 4-5-8 and
b. Weather Products.
FIS-B does not replace a preflight weather briefing
from a source listed in Paragraph 7-1-2, FAA
Weather Services, or inflight updates from an FSS or
ATC. FIS-B information may be used by the pilot for
the safe conduct of flight and aircraft movement;
however, the information should not be the only
source of weather or aeronautical information. A
pilot should be particularly alert and understand the
limitations and quality assurance issues associated
with individual products. This includes graphical
representation of next generation weather radar
(NEXRAD) imagery and Notices to Airmen
(NOTAM)/temporary flight restrictions (TFR).
AIM, Paragraph 7-1-11 , Flight Information Services
Advisory Circular AC 00-63, "Use of Cockpit Displays of Digital
Weather and Aeronautical Information"
Surveillance Systems 4-5-19