ENR 1.13  Unlawful interference

1 General

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, and ATS personnel reacting to acts of unlawful interference.

2 Aircrew Procedures
2.1 Unless considerations aboard the aircraft dictate otherwise, the pilot-in-command 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 within radar coverage.

Note: An aircraft equipped with a SSR transponder is expected to operate the transponder on Mode A Code 7500 to indicate specifically that it is the subject of unlawful interference. The aircraft may operate the transponder on Mode A Code 7700, to indicate that it is threatened by grave and imminent danger and requires immediate assistance.

2.2 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:
a) 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 and data links should also be used when it is advantageous to do so and circumstances permit; and
b) Proceed at a level, which differs from the cruising levels normally used for IFR flight by:
1) 150 m (500 ft) in an area where a vertical separation minimum of 300 m (1 000 ft) is applied; or
2) 300 m (1 000 ft) in an area where a vertical separation minimum of 600 m (2 000 ft) is applied.

Note: Action to be taken by an aircraft, which is intercepted while being subject to an act of unlawful interference is prescribed in ENR 1.12.

3 ATS Procedures
3.1 Whenever unlawful interference with an aircraft is known or suspected, or a bomb threat warning has been received, controllers shall promptly attend to requests by, or to anticipated needs of, the aircraft, including requests for relevant information relating to air navigation facilities, procedures and services along the trajectory and at any aerodrome of intended landing, and shall take such action as is necessary to expedite the conduct of all phases of the flight.
3.2 ATSUs or Sectors shall:
a) Transmit, and continue to transmit, information pertinent to the safe conduct of the flight, without expecting a reply from the aircraft. No reference shall be made to the nature of the emergency unless it has first been referred to in communications from the aircraft involved and it is certain that such reference will not aggravate the situation.
b) Monitor and plot the progress of the flight with the means that are available, and co-ordinate transfer of control with adjacent ATS units or sectors without requiring transmissions or other responses from the aircraft, unless communication with the aircraft remains normal;
c) Inform and continue to keep informed, appropriate ATS units and sectors, including those in adjacent FIRs, which may be concerned with the progress of the flight;

Note: In applying this provision, account must be taken of all the factors, which may affect the progress of the flight, including fuel endurance and the possibility of sudden changes in route and destination. The objective is to provide, as far in advance as is practicable in the circumstances, each ATSU or sector with appropriate information as to the expected or possible penetration of the aircraft into its area of responsibility.

d) Notify:
1) The operator or its designated representative;
2) The appropriate rescue co-ordination centre in accordance with appropriate alerting procedures;
3) The designated security authority;

It is assumed that the designated security authority and/or the operator will in turn notify other parties concerned in accordance with pre-established procedures.

e) Relay appropriate messages, relating to the circumstances associated with the unlawful interference, between the aircraft and designated authorities.
3.3 The following additional procedures shall apply if a threat is received indicating that a bomb or other explosive device has been placed on board a known aircraft. The ATSU receiving the threat information shall:
a) If in direct communication with the aircraft, advise the flight crew without delay of the threat and the circumstances surrounding the threat; or
b) If not in direct communication with aircraft, advise the flight crew by the most expeditious means through other ATS units, sectors or other channels.
3.4 The ATSU in communication with the aircraft shall ascertain the intentions of the flight crew and report those intentions to other ATSUs or sectors, which may be concerned with the flight.
3.5 The aircraft shall be handled in the most expeditious manner whilst ensuring, to the extent possible, the safety of other aircraft and that personnel and ground installations are not put at risk.
3.6 Aircraft in flight shall be given a re-clearance to a requested new destination without delay. Any request to climb or descend for the purpose of equalizing or reducing the differential between the outside air pressure and cabin air pressure shall be approved as soon as possible.
3.7 Controllers shall not provide any advice or suggestions concerning action to be taken by the flight crew in relation to an explosive device.
3.8 An aircraft on the ground should be advised to remain as far away from other aircraft and installations as possible, and if appropriate, to vacate the runway. The aircraft should be instructed to taxi to a designated or isolated parking area. Should the flight crew disembark passengers and crew immediately, other aircraft, vehicles and personnel should be kept at a safe distance from the threatened aircraft.
3.9 An aircraft known or believed to be the subject of unlawful interference or which for other reasons needs isolation from normal aerodrome activities shall be cleared to the designated isolated parking position.
3.10 Where such an isolated parking position has not been designated, or if the designated position is not available, the aircraft shall be cleared to a position within the area or areas selected by prior agreement with the aerodrome authority.
3.11 The taxi clearance shall specify the taxi route to be followed to the parking position. This route shall be selected with a view to minimize any security risks to the public, other aircraft and installations at the aerodrome.