NFC Learning

“traffic information” means information issued by an air traffic services unit to alert a pilot
to other known or observed air traffic which may be in proximity to the position or
intended route of flight and to help the pilot avoid a collision

Traffic information service – broadcast (TIS-B) IN. A surveillance function that receives and processes surveillance data from
TIS-B OUT data sources.

Traffic information service – broadcast (TIS-B) OUT. A function on the ground that periodically broadcasts the surveillance
information made available by ground sensors in a format suitable for TIS-B IN capable receivers.

Note.— This technique can be achieved through different data links. The requirements for Mode S extended squitters are
specified in Annex 10, Volume IV, Chapter 5. The requirements for VHF digital link (VDL) Mode 4 and universal access
transceiver (UAT) are specified in Annex 10, Volume III, Part I.
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Transfer of control point. A defined point located along the flight path of an aircraft, at which the responsibility for
providing air traffic control service to the aircraft is transferred from one control unit or control position to the next.

Transit delay. In packet data systems, the elapsed time between a request to transmit an assembled data packet and an
indication at the receiving end that the corresponding packet has been received and is ready to be used or forwarded.

“transition altitude” means the altitude above which the vertical position of an
aircraft is controlled by reference to flight levels instead of altitudes.

“transition level” means the altitude below which the vertical position of an
aircraft is controlled by reference to altitudes instead of flight levels

Travel document. A passport or other official document of identity issued by a State or organization, which may be used by
the rightful holder for international travel.

Tributary station. An aeronautical fixed station that may route receive or transmit messages and/or digital data but which does not relay except for the purpose of serving similar
stations connected through it to a communication centre.

Trigger NOTAM

When an AIP Amendment or an AIP Supplement is published in accordance with AIRAC procedures, a “trigger” NOTAM is originated and promulgated. The intent of this NOTAM is to serve as a reminder in the pre-flight information bulletin (PIB) by signalling the coming into effect of operationally significant permanent or temporary changes to the AIP, thus ensuring that users are aware of changes that may affect their flights. It also serves as a reminder to AIS officers responsible for updating AIP to insert a new AIP Amendment or AIP Supplement in the affected AIP on the amendment or supplement effective date.

Tropical cyclone. Generic term for a non-frontal synoptic-scale cyclone originating over tropical or sub-tropical waters with
organized convection and definite cyclonic surface wind circulation.