ENR 1.13  Unlawful interference

ENR 1.13.1   General

ENR 1.13.1.1 An aircraft which is being subjected to unlawful interference shall endeavour to set the transponder to Code 7500 and notify the appropriate ATS unit of, any significant circumstances associated therewith and any deviation from the current flight plan necessitated by the circumstances, in order to enable the ATS unit to give priority to the aircraft and to minimise conflict with other aircraft.
ENR 1.13.1.2 If an aircraft is subjected to unlawful interference, the pilot-in-command shall attempt to land as soon as practicable at the nearest suitable aerodrome or at a dedicated aerodrome assigned by the appropriate authority unless considerations aboard the aircraft dictate otherwise.

ENR 1.13.2   Transponder operations - unlawful interference with aircraft in flight

ENR 1.13.2.1 If there is unlawful interference with an aircraft in flight, the pilot-in-command shall attempt to set the transponder to Mode A Code 7500 in order to indicate the situation. If circumstances so warrant, Code 7700 should be used instead.
ENR 1.13.2.2 If a pilot has selected Mode A Code 7500 and has been requested to confirm this code by ATC, the pilot shall, according to circumstances, either confirm this or not reply at all.

Note: If the pilot does not reply, ATC will take this as confirmation that the use of Code 7500 is not an inadvertent false code selection.

ENR 1.13.3   Procedures

  1. The following procedures are intended as guidance for use by aircraft when unlawful interference occurs and the aircraft is unable to notify an ATS unit of this fact.
  2. If the pilot-in-command cannot proceed to an aerodrome in accordance with the ENR 1.13.1.2, he/she should attempt to continue flying on the assigned track and at the assigned cruising level at least until able to notify an ATS unit or until within radar coverage.
  3. When an aircraft subjected to an act of unlawful interference must depart from its assigned track or its assigned cruising level without being able to make radiotelephony contact with ATS, the pilot-in command should, whenever possible:
    1. Attempt to broadcast warnings on the VHF emergency frequency and other appropriate frequencies, unless considerations aboard the aircraft dictate otherwise. Other equipment such as on board transponders, data links, etc. should also be used when it is advantageous to do so and circumstances permit; and
    2. proceed at a level which differs from the cruising levels normally used for IFR flight by:
      • 150 M (500 FT) in airspace between FL 290 and FL 410 inclusive (RVSM airspace within the FIR ZAGREB) or
      • 300 M (1000 FT) in airspace below FL 290 and above FL 410 (NON RVSM airspace within the FIR ZAGREB).

    Note: If the pilot does not reply, ATC will take this as confirmation that the use of Code 7500 is not an inadvertent false code selection.

ENR 1.13.4   Aircraft hijacking

  1. When a hijacking attempt or a criminal act of hijacking an aircraft occurs during a flight, the aircraft crew shall, depending on circumstances, undertake the necessary measures for the safety of aircraft and the persons on board.
  2. When possible, the aircraft pilot shall inform the ATC unit about the hijacking, and shall act in accordance with provisions of item ENR 1.13.2 and ENR 1.13.3 herein, and report the aircraft call sign and current position, circumstances and nature of danger, as well as his/her further actions.

Note: The ATC unit shall verify without delay by radio communication whether the SSR transponder setting as stipulated by the procedure from Paragraph b. of this item was deliberate or accidental, and shall provide all available assistance to the aircraft.