ENR 1.12  Interception of civil aircraft

ENR 1.12.1.   Interception procedures

The following procedures and visual signals apply over the territory and territorial waters of the Republic of Croatia in the event of interception* of an aircraft. An aircraft which is intercepted by another aircraft shall immediately:
  1. follow the instructions given by the intercepting aircraft, interpreting and responding to visual signals in accordance with the specifications in Appendix 1 of ICAO Annex 2;
  2. notify, if possible, the appropriate air traffic services unit;
  3. attempt to establish radiocommunication with the intercepting aircraft or with the appropriate intercept control unit, by making a general call on the emergency frequency 121.500 MHZ and/or 243.000 MHZ, giving his call sign, position of the aircraft and the nature of the flight;
  4. if equipped with SSR transponder, select Mode A, Code 7700, unless otherwise instructed by the appropriate air traffic services unit.

* The word “interception” in this context does not include intercept and escort service provided, on request, to an aircraft in distress, in accordance with the Search and Rescue Manual (Doc 7333).

If radio contact is established during interception but communication in a common language is not possible, attempts shall be made to convey instructions, acknowledgement of instructions and essential information by using the phrases and pronunciations in the following table, transmitting each phrase twice:
PhrasePronunciation*Meaning
CALL SIGN(call sign)*KOL SA-INMy call sign is (call sign)
WILCOVILL-KOUnderstood. Will comply!
CAN NOTKANN NOTTUnable to comply!
REPEATREE-PEETRepeat your instruction!
AM LOSTAM LOSSTPosition unknown!
MAYDAYMAYDAYI am in distress!
HIJACK*HI-JACKI have been hijacked!
LAND (place name)LAAND (place name)I request to land at (place name)!
DESCENDDEE-SENDI require descent!
The phrases shown in the table below shall be used by the intercepting aircraft and transmitted twice in the circumstances described in the preceding paragraph.
If any instructions received by radio from any sources conflict with those given by the intercepting aircraft by visual signals, the intercepted aircraft shall request immediate clarification while continuing to comply with the visual instructions given by the intercepting aircraft.
If instructions received by radio from any sources conflict with those given by the intercepting aircraft by radio, the intercepted aircraft shall request immediate clarification while continuing to comply with the radio instructions given by the intercepting aircraft.
During the intercepting procedure, the pilot of an interceptor equipped with an SSR transponder shall suspend transmission of information on an altitude which is at a distance of 20 NM (37 KM) from an aircraft he intends to intercept (whichever occurs earlier), in order to prevent undesirable resolution information at the intercepted aircraft that is equipped with an ACAS.
The visual signals for use in the event of interception are detailed on page ENR 1.12-2.
PhrasePronunciation*Meaning
CALL SIGNKOL SA-INWhat is your call sign?
FOLLOWFOL-LOFollow me!
DESCENDDEE-SENDDescend for landing!
YOU LANDYOU LAANDLand at this aerodrome!
PROCEEDPRO-SEEDYou may proceed!

ENR 1.12.2.   Signals for use in the event of interception


1. Signals initiated by intercepting aircraft and responses by intercepted aircraft
SeriesINTERCEPTING Aircraft SignalsMeaningINTERCEPTED Aircraft RespondsMeaning
1DAY or NIGHT - Rocking aircraft andflashing navigational lights at irregularintervals (and landing lights in the case of a helicopter) from a position slightly above and ahead of, and normally to the left of, the intercepted aircraft (or to the right if the intercepted aircraft is a helicopter) and, after acknowledgement, a slow level turn, normally to the left, (or to the right in the case of a helicopter) on the desired heading.

Note 1: Meteorological conditions or terrain may require the intercepting aircraft to reverse the positions and direction of turn given above in Series 1.

Note 2: If the intercepted aircraft is notable to keep pace with the interceptingaircraft, the latter is expected to fly aseries of race-track patterns and rock the aircraft each time it passes the intercepted aircraft.		You have beenintercepted.Follow me.DAY or NIGHT - Rocking aircraft,flashing navigational lights at irregularintervals and following.

Note: Additional action required to betaken by intercepted aircraft is prescribed in Annex 2., Chapter 3, 3.8		Understood, will comply.
2DAY or NIGHT - An abrupt break-away manoeuvre from the intercepted aircraft consisting of a climbing turn of 90 degrees or more without crossing the line of flight of the intercepted aircraft.You may proceed.DAY or NIGHT - Rocking the aircraft.Understood, will comply.
3DAY or NIGHT - Lowering landing gear (if fitted), showing steady landing lights and overflying runway in use or, if the intercepted aircraft is a helicopter, overflying the helicopter landing area. In the case of helicopters, the intercepting helicopter makes a landing approach, coming to hover near to the landing area.Land at this aerodrome.DAY or NIGHT - Lowering landing gear, (if fitted), showing steady landing lights and following the intercepting aircraft and, if, after overflying the runway in use or helicopter landing area, landing is considered safe, proceeding to land.Understood, will comply.

2. Signals initiated by intercepted aircraft and responses by intercepting aircraft
SeriesINTERCEPTED Aircraft SignalsMeaningINTERCEPTING Aircraft RespondsMeaning
4DAY or NIGHT - Raising landing gear (if fitted) and flashing landing lights while passing over runway in use or helicopter landing area at a height exceeding 300 M (1 000 FT) but not exceeding 600 M (2 000 FT) (in the case of a helicopter, at a height exceeding 50 M (170 FT) but not exceeding 100 M (300 FT) above the aerodrome level, and continuing to circle runway in use or helicopter landing area. If unable to flash landing lights, flash anyother lights available.Aerodrome you have designated is inadequate.DAY or NIGHT - If it is desired that the intercepted aircraft follow intercepting aircraft to an alternate aerodrome, the intercepting aircraft raises its landing gear (if fitted) and uses the Series 1 signals prescribed for intercepting aircraft.

If it is decided to release the intercepted aircraft, the intercepting aircraft uses the Series 2 signals prescribed for intercepting aircraft.		Understood, follow me.
5DAY or NIGHT - Regular switching on and off of all available lights but in such a manner as to be distinct from flashing lights.Cannot comply.DAY or NIGHT - Use Series 2 signals prescribed for intercepting aircraft.Understood.
6DAY or NIGHT - Irregular flashing of all available lights.In distress.DAY or NIGHT - Use Series 2 signals prescribed for intercepting aircraft.Understood.