ICAO Annex 11 states that Traffic Information Broadcasts by Aircraft "are intended to permit reports and relevant supplementary information of an advisory nature to be transmitted by pilots on a designated VHF radiotelephone (RTF) frequency for the information of pilots of other aircraft in the vicinity" in the absence of air traffic service. It notes that TIBAs "should be made only when necessary and only as a temporary measure.
Designation of TIBA Areas
ICAO envisages that TIBA procedures should only apply in designated airspace where either it is necessary "to supplement collision hazard information provided by air traffic services outside controlled airspace" or "there is a temporary disruption of normal air traffic services". In the former case, if more than one Member State is involved in a designation, it is expected that it will be promulgated in ICAO Doc 7030. Airspace and frequency designation for TIBA is considered to be the responsibility of the Member State and should be promulgated by means of a NOTAM which details the message formats and procedures to be used. ICAO also expects that TIBA designations will be reviewed at intervals "not exceeding 12 months". It is accepted that if a TIBA procedure is being introduced because of a temporary disruption to the provision of ATS in controlled airspace, then one or more frequencies normally used for that purpose in the designated airspace may be used for TIBA.
Typical Aircraft Procedures
These involve the maintenance of a listening watch on the TIBA frequency from 10 minutes prior to entering the designated airspace until leaving it. If an aircraft is departing from an aerodrome within or beneath the designated airspace, the listening watch should begin as soon as appropriate after takeoff.
An initial 'All Stations' broadcast should normally be made 10 minutes before the ETA at the boundary of the designated airspace (or as soon as appropriate if taking off within or below it) and further broadcasts, similarly addressed, should then be made at any time the pilot considers necessary and specifically:
- prior to crossing any reporting point or joining an ATS route
- at not less than 20 minute intervals
- where possible 2-5 minutes prior to an intended change of flight level
- as a flight level change is commenced
It is not expected that 'All Stations' broadcasts will be acknowledged unless it appears that there may be a risk of collision. It is also usually recommended to maintain the established cruising level unless traffic conflict or adverse weather avoidance is necessary.
Unless a potential conflict can be resolved in accordance with the standard right-of-way provisions and unless an alternative manoeuvre appears more appropriate, an immediate descent of 500 feet (or 1000 feet if above FL290 in an area where a 2000 feet vertical separation minimum applies) should be made with a broadcast to the other traffic of the action taken. A return to the pre-manoeuvre flight level should be made as soon as practicable.
The action taken and the return to the pre-manoeuvre flight level should be advised to the appropriate ATS frequency and the display all available aircraft lighting which might improve the visual acquisition of the manoeuvring aircraft is recommended.
Transponders should be operated as per ICAO PANS OPS Doc 8168, using Code 2000 even if outside radar coverage so that TCAS is enabled.
Prevalence of TIBA Designated Areas
Improvements in ATS mean that with one exception - large parts of the ICAO Africa Indian Ocean (AFI) Region - TIBA procedures are now more likely to be encountered as temporary rather than long term arrangements. The AFI situation has been dealt for many years now by promulgation of the IATA In-Flight Broadcast Procedure (IFBP), which is endorsed by ICAO. The IATA AFI IFBP advises the application of IFBP when flying in any of the following group of contiguous FIRs in Africa using frequency 126.9 MHz:
IATA regularly reviews whether the included FIRs remain appropriate and notifies any changes to them. It is noted that the Libyan authorities have mandated IFBP throughout the Tripoli FIR i.e. to include that part of it north of 30° N.
Other applications by IATA of their IFBP procedure have included in the Yangon FIR (Myanmar) since 2003 due to numerous reports indicating that Myanmar’s fixed and mobile communications had been operating below the appropriate level of reliability.
TIBA as a contingency measure was briefly implemented in New Zealand after the 2011 earthquake which resulted in the evacuation of the Christchurch ACC and the procedure has been used on various occasions in Australia since 2008 due to temporary controller shortages and more recently in Class G airspace within the Kota Kinabalu FIR (Malaysia).