Chapter 2
Annex 11 — Air Traffic Services
Note 4.— The schedule of the predetermined, internationally agreed AIRAC common effective dates at intervals of 28 days, including 6 November 1997, and guidance for the AIRAC use are contained in the Aeronautical Information Services Manual (Doc 8126, Chapter 3, 3.1 and Chapter 4, 4.4).
safe conduct of the flight shall continue to be transmitted and necessary action shall be taken to expedite the conduct of all phases of the flight, especially the safe landing of the aircraft.
2.23 In-flight contingencies 2.23.1 2.21
Note 1.— The terms “strayed aircraft” and “unidentified aircraft” in this paragraph have the following meanings:
Minimum flight altitudes shall be determined and promulgated by each Contracting State for each ATS route and control area over its territory. The minimum flight altitudes determined shall provide a minimum clearance above the controlling obstacle located within the areas concerned.
Strayed aircraft. An aircraft which has deviated significantly from its intended track or which reports that it is lost. Unidentified aircraft. An aircraft which has been observed or reported to be operating in a given area but whose identity has not been established.
Note.— The requirements for publication by States of minimum flight altitudes and of the criteria used to determine them are contained in Annex 15, Appendix I. Detailed obstacle clearance criteria are contained in PANS-OPS (Doc 8168), Volume I, Part VI and Volume II, Part III and Part VI.
2.22
Strayed or unidentified aircraft
Minimum flight altitudes
Note 2.— An aircraft may be considered, at the same time, as a “strayed aircraft” by one unit and as an “unidentified aircraft” by another unit. 2.23.1.1 As soon as an air traffic services unit becomes aware of a strayed aircraft it shall take all necessary steps as outlined in 2.23.1.1.1 and 2.23.1.1.2 to assist the aircraft and to safeguard its flight.
Service to aircraft in the event of an emergency
2.22.1 An aircraft known or believed to be in a state of emergency, including being subjected to unlawful interference, shall be given maximum consideration, assistance and priority over other aircraft as may be necessitated by the circumstances.
Note.— Navigational assistance by an air traffic services unit is particularly important if the unit becomes aware of an aircraft straying, or about to stray, into an area where there is a risk of interception or other hazard to its safety.
Note.— To indicate that it is in a state of emergency, an aircraft equipped with an appropriate data link capability and/ or an SSR transponder might operate the equipment as follows:
2.23.1.1.1 If the aircraft’s position is not known, the air traffic services unit shall: a) attempt to establish two-way communication with the aircraft, unless such communication already exists;
a) on Mode A, Code 7700; or b) use all available means to determine its position; b) on Mode A, Code 7500, to indicate specifically that it is being subjected to unlawful interference; or
c) inform other ATS units into whose area the aircraft may have strayed or may stray, taking into account all the factors which may have affected the navigation of the aircraft in the circumstances;
c) activate the appropriate emergency and/or urgency capability of ADS; or d) transmit the appropriate emergency message via CPDLC.
d) inform, in accordance with locally agreed procedures, appropriate military units and provide them with pertinent flight plan and other data concerning strayed aircraft;
2.22.1.1 Recommendation.— In communications between ATS units and aircraft in the event of an emergency, Human Factors principles should be observed.
e) request from the units referred to in c) and d) and from other aircraft in flight every assistance in establishing communication with the aircraft and determining its position.
Note.— Guidance material on Human Factors principles can be found in the Human Factors Training Manual (Doc 9683). 2.22.2 When an occurrence of unlawful interference with an aircraft takes place or is suspected, ATS units shall attend promptly to requests by the aircraft. Information pertinent to the
Note.— The requirements in d) and e) apply also to ATS units informed in accordance with c). 2-9
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