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AIM

10/12/17

4−5−19

Surveillance Systems

altitudes near some airports, with subsequently

limited TIS−B service volume coverage. If there is

no radar coverage in a given area, then there will be

no TIS−B coverage in that area.

d. TIS−B Limitations.

1. TIS−B is NOT intended to be used as a

collision avoidance system and does not relieve the

pilot’s responsibility to “see and avoid” other aircraft,

in accordance with 14CFR §91.113b. TIS−B must

not be used for avoidance maneuvers during times

when there is no visual contact with the intruder

aircraft. TIS−B is intended only to assist in the visual

acquisition of other aircraft.

NOTE−

No aircraft avoidance maneuvers are authorized as a

direct result of a TIS−B target being displayed in the

cockpit.

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

display.

(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

traffic.

(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

system.

4−5−9. Flight Information Service−

Broadcast (FIS−B)

a. Introduction.

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

FIG 4−5−9.)