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North Atlantic (NAT)

International Operations Regional

Regional differences from the ICAO standard can be found in ICAO Document 7030 and your Jeppesen Airway Manual. Both of the sources, however, can be out of date. See Regional Introduction for ideas about getting up-to-date information.


Communications

There are a lot of communications procedures that we assume are required worldwide. In truth, about the only place you will find these specified are in NAT Doc 007. So they best practices just about everywhere in the world and they are mandatory in the North Atlantic.

ATS Communications

[NAT Doc 007, ¶6.1.1] It is important that pilots appreciate that routine air/ground ATS Voice communications in the NAT Region are conducted via aeradio stations staffed by communicators who have no executive ATC authority. Messages are relayed by the ground station to/from the air traffic controllers in the relevant OAC. This is the case, whether communications are via HF, GP/VHF or SATCOM Voice.

[NAT Doc 007, ¶6.1.2] There are six radio stations in the NAT: Bodø Radio (Norway), Gander Radio (Canada), Iceland Radio (Iceland), New York Radio (USA), Santa Maria Radio (Portugal) and Shanwick Radio (Ireland).

[NAT Doc 007, ¶6.1.3] Even with the growing use of data link communications a significant volume of NAT air/ground communications are conducted using voice on SSB HF frequencies and GP VHF frequencies. To support air/ground ATC communications in the North Atlantic region, twenty-four HF frequencies have been allocated, in bands ranging from 2.8 to 18 MHz. Additionally, Shanwick Radio, Santa Maria Radio, and Iceland Radio operate a number of Regional and Domestic Air Route Area (RDARA) frequencies in accordance with operating requirements and agreements between the stations.

[NAT Doc 007, ¶6.1.4] There are a number of factors which affect the optimum frequency for communications over a specific path. The most significant is the diurnal variation in intensity of the ionisation of the refractive layers of the ionosphere. Hence frequencies from the lower HF bands tend to be used for communications during night-time and those from the higher bands during day-time. Generally in the North Atlantic frequencies of less than 6 MHz are utilised at night and frequencies of greater than 5 MHz during the day.

[NAT Doc 007, ¶6.1.5] The 24 NAT frequencies are organized into six groups known as Families. The families are identified as NAT Family A, B, C, D, E and F. Each family contains a range of frequencies from each of the HF frequency bands. A number of stations share families of frequencies and co-operate as a network to provide the required geographical and time of day coverage. A full listing of the frequencies operated by each NAT radio station is contained in the “HF Management Guidance Material for the North Atlantic Region” (NAT Doc 003), available at https://www.icao.int/EURNAT/Pages/welcome.aspx following “EUR & NAT Documents”, then “NAT Documents”, in folder “NAT Doc 003”.

[NAT Doc 007, ¶6.1.6] Each individual flight may be allocated a primary and a secondary HF frequency before the oceanic boundary.

[NAT Doc 007, ¶6.1.7] Radio operators usually maintain a listening watch on more than one single frequency therefore it is useful for flight crews to state the frequency used when placing the initial call to the radio station.

SELCAL

[NAT Doc 007, ¶6.1.19] When using HF, SATVOICE, or CPDLC, flight crews should maintain a listening watch on the assigned frequency, unless SELCAL equipped, in which case they should ensure the following sequence of actions:

  • provide the SELCAL code in the flight plan; (any subsequent change of aircraft for a flight will require passing the new SELCAL information to the OAC);
  • check the operation of the SELCAL equipment, at or prior to entry into Oceanic airspace, with the appropriate aeradio station. (This SELCAL check must be completed prior to commencing SELCAL watch); and
  • maintain thereafter a SELCAL watch.

SATVOICE Communications

[NAT Doc 007, ¶6.1.28] The Aeronautical Mobile Satellite (Route) Service (AMS(R)S), more commonly referred to as SATVOICE, can be used as a supplement to HF & CPDLC communications throughout the NAT region for any routine, non-routine or emergency ATS air/ground communications. NAT ATS provider State AIPs contain the necessary telephone numbers and/or short-codes for air-initiated call access to radio stations and/or direct to OACCs. Since oceanic traffic typically communicates with ATC through radio facilities, routine SATVOICE calls should be made to such a facility rather than the ATC Centre. Only when the urgency of the communication dictates otherwise should SATVOICE calls be made to the ATC Centre. SATVOICE communication initiated due to HF propagation difficulties does not constitute urgency and should be addressed to the air-ground radio facility. The use of SATVOICE is described in The SATVOICE Operations Manual (ICAO Doc 10038).

[NAT Doc 007, ¶6.1.29] The provisions governing the use of SATVOICE for ATS communications in the NAT region are contained in Doc.7030. These provisions include that even when using SATVOICE, flight crews must simultaneously operate SELCAL or maintain a listening watch on the assigned HF/VHF frequency.

[NAT Doc 007, ¶6.1.30] Operators must also recognise that they are bound by their own State of Registry’s regulations regarding carriage and use of any and all long-range ATS communications equipment. Some States do not authorise the carriage of SATVOICE as redundancy for HF equipage. However, in other instances MMEL remarks for HF systems do provide relief for SATVOICE equipped aircraft, thereby making the requirement for the carriage of fully serviceable/redundant HF communications equipment less of an issue (See also Section 6.6 regarding the use of SATVOICE in the event of “HF Communications Failure”).

Data Link Communications

[NAT Doc 007, ¶6.1.31] Data link communications have been gradually introduced into the NAT for position reporting (via ADS-C & CPDLC) and air/ground ATC communications using FANS 1/A CPDLC. Operational procedures are specified in ICAO Doc 10037, “Global Operational Data Link (GOLD) Manual”. AIS publications of the NAT ATS provider States should be consulted to determine the extent of current implementation in each of the North Atlantic OCAs.

[NAT Doc 007, ¶6.1.32] When operating CPDLC, the aircraft data link system provides indication to flight crews of any degraded performance which results from a failure or loss of connectivity. The flight crew should then notify the ATS unit of the failure as soon as practicable. Timely notification is essential to ensure that the ATS unit has time to assess the situation and apply a revised separation standard, if necessary.

[NAT Doc 007, ¶6.1.33] Similar to SATVOICE usage, flight crews electing to use Data link communications for regular ATS communications in the ICAO NAT region remain responsible for operating SELCAL (including completion of a SELCAL Check), or maintaining a listening watch on the assigned HF frequency outside VHF coverage. As stated in section 2.1.4 of the ICAO Global Operational data Link (GOLD) Manual (Doc 10037) ANSPs are required to notify operators, using the AIP or other appropriate AIS, the detail of all the supported data link services. Such notification will include advice when the aircraft SATCOM system is not serviceable. In such circumstances, when the planned route of flight is to extend beyond VHF coverage, the ANSP may restrict the use of CPDLC and ADS-C, even within VHF coverage areas, if so Operators should then ensure that the relevant CPDLC/ADS-C descriptors (J5/P2/D1) are not filed.

[NAT Doc 007, ¶6.1.34] Flights equipped with CPDLC and /or ADS-C should ensure that the data link system is logged on to the appropriate OACC. This applies even when the aircraft is provided with ATS Surveillance services. With the introduction of PBCS separation, establishing and maintaining a data link connection becomes even more important since an active data link connection is one of the requirements for the application of the separation. CPDLC provides communication redundancy and controllers will in many cases use CPDLC for communication even though the flight crew is maintaining a listening watch on the assigned DCPC VHF frequency. ADS-C furthermore enables ATC to perform route conformance monitoring for downstream waypoints.

The MNPS has been replaced by the North Atlantic High Level Airspace (NAT HLA) but ICAO Doc 7030 hasn't caught up yet. For now, you can just associate NAT HLA with MNPS.

More about this: North Atlantic Airspace (NAT HLA).

This region is moving from a mix of navigation requirements to the system of Performance Based Navigation outlined in ICAO Document 9613. Current navigation requirements are available on Jeppesen Airway Manual Air Traffic Control pages and Chapter 4 of each region covered by ICAO Document 7030.

RNAV 10 (RNP 10)

[ICAO Doc 7030 Amendment 1, §NAT, ¶4.1.1.1.]

  • A lateral separation minimum of 93 km (50 NM) may be applied between flights operating within the control area of the New York Oceanic FIR.
  • The aircraft and operator must be approved RNP 10 or RNP 4 by the State of the Operator or the State of Registry, as appropriate. RNP 10 is the minimum navigation specification for the application of 93 km (50 NM) lateral separation.

More about this:Required Navigation Performance-10 (RNP-10).

Keep in mind RNP 10 is an exception to the rule of Required Navigation Performance standards, "RNAV 10" retains the "RNP 10" designation for matters of convenience.

Minimum Navigation Performance Specifications (MNPS)

[ICAO Doc 7030 Amendment 1, §NAT, ¶4.1.1.5.1.]

  • The MNPS shall be applicable in that volume of airspace between FL 285 and FL 420 within the Oceanic Control Areas of Santa Maria, Shanwick, Reykjavik, Gander Oceanic and New York Oceanic, excluding the area west of 60°W and south of 38°30′N.
  • For flights within the volume of airspace specified in 4.1.1.5.1.1 aircraft shall have lateral navigation performance capability such that:
    1. the standard deviation of lateral track errors shall be less than 11.7 km (6.3 NM);
    2. the proportion of the total flight time spent by aircraft 56 km (30 NM) or more off the cleared track shall be less than 5.3 × 10-4; and
    3. the proportion of the total flight time spent by aircraft between 93 and 130 km (50 and 70 NM) off the cleared track shall be less than 1.3 × 10-5.

WGS-84 Compliance

All three countries listed in the NAT region, the Azores, Greenland, and Iceland are listed as WGS-84 in the Jeppesen WGS-84 website, but Greenland is listed only as partially compliant in their Jeppesen Airway Manual ATC page, dated 16 Aug 2013.

More about this: World Geodetic System 84 (WGS-84).

Surveillance

Operation of your transponder is standard with the exception of the need to wait 30 minutes before switching to Code 2000.

[NAT Doc 007, ¶6.8] OPERATION OF TRANSPONDERS

  • All aircraft operating as IFR flights in the NAT Region shall be equipped with a pressure altitude reporting SSR transponder. Unless otherwise directed by ATC, pilots flying in the NAT FIRs will operate transponders continuously in Mode A/C Code 2000, except that the last assigned code will be retained for a period of 30 minutes after entry into NAT airspace or after leaving a radar service area. Pilots should note that it is important to change from the last assigned domestic code to the Mode A/C Code 2000 since the original domestic code may not be recognised by the subsequent Domestic Radar Service on exit from the oceanic airspace. One exception to this requirement should be noted. Because of the limited time spent in the NAT HLA, when flying on Route Tango 9, the change from the last assigned domestic code to Code 2000 should be made Northbound 10 minutes after passing BEGAS and Southbound 10 minutes after passing LASNO.
  • It should be noted that this procedure does not affect the use of the special purpose codes (7500, 7600 and 7700) in cases of unlawful interference, radio failure or emergency. However, given the current heightened security environment crews must exercise CAUTION when selecting Codes not to inadvertently cycle through any of these special purpose codes and thereby possibly initiate the launching of an interception.
  • Reykjavik ACC provides a radar control service in the south-eastern part of its area and consequently transponder codes issued by Reykjavik ACC must be retained throughout the Reykjavik OCA until advised by ATC.
  • RVSM

    [ICAO Doc 7030 Amendment 1, §NAT, ¶4.2.1.] RVSM shall be applicable in that volume of airspace between FL 290 and FL 410 inclusive in all FIRs of the NAT Region.

    Altimeter Procedures

    Transition altitude and level procedures vary by country.

    Special Routings

    The Organized Track System (OTS) carries with it all the restrictions of flying in the NAT HLA plus a few more. You must also be careful in that there are several layers of authorizations involved. You could be permitted the lower altitudes and standard spacing, all altitudes with the chance of decreased longitudinal spacing, and all altitudes with the chance of decreased longitudinal and lateral spacing.

    images

    Photo: Example of Daytime Westbound NAT Organized Track System, NAT Doc 007, Figure 2.

    Click photo for a larger image

    See: Airspace / NAT HLA.

    ICAO Differences

    Each country departs in some ways with the ICAO standard and common US practices. Pilots should always refer to the Jeppesen Airway Manual, Air Traffic Control, State Rules and Procedures pages for each country on their itineraries for differences with ICAO Standards, Recommended Practices and Procedures. More about this: US versus ICAO.

    The following are a sampling of some of the differences, there are many more. You should check the Jeppesen Airway Manual State pages for every country you takeoff, overfly, or land.

    Lost Communications

    [NAT Doc 007, ¶6.6.1] Rules and procedures for the operation of an aircraft following a radio communications failure (RCF) are established to allow ATC to anticipate that aircraft’s subsequent actions and thus for ATC to be able to provide a service to all other flights within the same vicinity, so as to ensure the continued safe separation of all traffic. The general principles of such rules and procedures are set out in Annexes 2 and 10 to the ICAO Convention. States publish in their AIPs specific RCF rules and regulations to be followed within their particular sovereign airspace.

    [NAT Doc 007, ¶6.6.2] It must be recognised that there is in general an underlying premise in “normal” radio communications failure procedures that they are for use when a single aircraft suffers an on-board communications equipment failure. Within the NAT Region and some adjacent domestic airspace (e.g. Northern Canada), where HF Voice is used for air-ground ATC communications, ionospheric disturbances resulting in poor radio propagation conditions can also interrupt these communications. While it is impossible to provide guidance for all situations associated with an HF communications failure, it is, however, extremely important to differentiate between two distinct circumstances: - firstly, an on-board communications equipment failure, resulting in an individual aircraft losing HF communications with ATC and; secondly, the occurrence of poor HF propagation conditions (commonly referred to as “HF Blackouts”), which can simultaneously interrupt HF air-ground communications for many aircraft over a wide area.

    [NAT Doc 007, ¶6.6.3] In the case of an on-board communications equipment failure, even though ATC loses contact with that aircraft, it can anticipate that aircraft’s actions and, if necessary, modify the profiles of other aircraft in the same vicinity in order to maintain safe separations.

    [NAT Doc 007, ¶6.6.4] However, the occurrence of poor HF propagation conditions can simultaneously interrupt HF air-ground communications for many aircraft over a wide area and ATC may then be unable to make any interventions to assure safe traffic separations using HF. Notwithstanding the growing use of Data link and SATVOICE for regular air-ground ATS communications in the NAT region, all flight crews must recognise that, pending the mandatory carriage and use of such means, an HF blackout will impact the ability of ATC to ensure the safe separation of all traffic. Hence, even if using other than HF for regular communications with ATC, flight crews should still exercise appropriate caution when HF blackout conditions are encountered.

    [NAT Doc 007, ¶6.6.5] The following procedures are intended to provide general guidance for aircraft which experience a communications failure while operating in, or proposing to operate in, the NAT region. These procedures are intended to complement and not supersede State procedures/regulations.

    General Provisions

    1. The flight crew of an aircraft experiencing a two-way ATS communications failure should operate the SSR Transponder on identity Mode A Code 7600 and Mode C.
    2. When so equipped, an aircraft should use SATVOICE to contact the responsible radio station via special telephone numbers/short codes published in State AIPs (see also NAT Doc 003, “High Frequency Management Guidance Material for the NAT Region” which can be downloaded from the www.icao.int/EURNAT/, following “EUR & NAT Documents”, then “NAT Documents”). However, it must be appreciated that pending further system developments and facility implementations the capability for Ground (ATC)-initiated calls varies between different NAT OACCs.
    3. If the aircraft is not equipped with SATVOICE then the flight crew should attempt to use VHF to contact any (other) ATC facility or another aircraft, inform them of the difficulty, and request that they relay information to the ATC facility with which communications are intended.
    4. The inter-pilot air-to-air VHF frequency, 123.450 MHz, may be used to relay position reports via another aircraft. (N.B. The emergency frequency 121.5 MHz should not be used to relay regular communications, but since all NAT traffic is required to monitor the emergency frequency, it may be used, in these circumstances, to establish initial contact with another aircraft and then request transfer to the inter-pilot frequency for further contacts).
    5. In view of the traffic density in the NAT region, flight crews of aircraft experiencing a two-way ATS communications failure should broadcast regular position reports on the inter-pilot frequency (123.450 MHz) until such time as communications are re-established.

    Communications Procedures for Use in the Event of an On-board HF Equipment Failure

    [NAT Doc 007, ¶6.6.6] Use SATVOICE communications, if so equipped. (See General Provisions 2. above).

    [NAT Doc 007, ¶6.6.7] If not SATVOICE equipped try VHF relay via another aircraft (See 6.6.5).

    Communications Procedures for Use during Poor HF Propagation Conditions

    [NAT Doc 007, ¶6.6.8] Poor HF propagation conditions are the result of ionospheric disturbances. These are usually caused by sun-spot or solar flare activity creating bursts of charged particles in the solar wind which can spiral down around the Earth’s magnetic lines of force and distort or disturb the ionised layers in the stratosphere which are utilised to refract HF radio waves. As with the Aurora Borealis, which is of similar origin, these ionospheric disturbances most commonly occur in regions adjacent to the Magnetic Poles. Since the Earth’s North Magnetic Pole is currently located at approximately 87N 150W, flights through the North Atlantic and Northern Canada regions can, on occasion, experience resulting HF communications difficulties.

    [NAT Doc 007, ¶6.6.9] SATVOICE communications are unaffected by most ionospheric disturbances. Therefore, when so equipped, an aircraft may use SATVOICE for ATC communications (See 6.6.5).

    [NAT Doc 007, ¶6.6.10] If not SATVOICE equipped, in some circumstances it may be feasible to seek the assistance, via VHF, of a nearby SATVOICE equipped aircraft to relay communications with ATC (See 6.6.5).

    [NAT Doc 007, ¶6.6.11] Whenever aircraft encounter poor HF propagation conditions that would appear to adversely affect air-ground communications generally, it is recommended that all flight crews then broadcast their position reports on the air-to-air VHF frequency 123.450 MHz. Given the density of traffic in the NAT region and the fact that in such poor propagation conditions ATC will be unable to maintain contact with all aircraft, it is important that even those aircraft that have been able to establish SATVOICE contact also broadcast their position reports.

    [NAT Doc 007, ¶6.6.12] If for whatever reason SATVOICE communications (direct or relayed) are not possible, then the following procedures may help to re-establish HF communications. Sometimes these ionospheric disturbances are very wide-spread and HF air-ground communications at all frequencies can be severely disrupted throughout very large areas (e.g. simultaneously affecting the whole of the NAT region and the Arctic.). However, at other times the disturbances may be more localised and/or may only affect a specific range of frequencies.

    [NAT Doc 007, ¶6.6.13] In this latter circumstance, HF air-ground communications with the intended radio station may sometimes continue to be possible but on a frequency other than either the primary or secondary frequencies previously allocated to an aircraft. Hence, in the event of encountering poor HF propagation conditions flight crews should first try using alternative HF frequencies to contact the intended radio station.

    [NAT Doc 007, ¶6.6.14] However, while the ionospheric disturbances may be severe, they may nevertheless only be localized between the aircraft’s position and the intended radio station, thus rendering communications with that station impossible on any HF frequency. But the radio stations providing air-ground services in the NAT region do co-operate as a network and it may, even then, still be possible to communicate with another radio station in the NAT network on HF and request that they relay communications. Efforts should therefore be made to contact other NAT radio stations via appropriate HF frequencies.

    [NAT Doc 007, ¶6.6.15] Nevertheless, as previously indicated, there are occasions when the ionospheric disturbance is so severe and so widespread that HF air-ground communications with any radio station within the NAT region network are rendered impossible.

    Rationale for Lost Communications Operational Procedures

    [NAT Doc 007, ¶6.6.16] Because of the density of oceanic traffic in the NAT region, unique operational procedures have been established to be followed by flight crews whenever communications are lost with ATC. If communications with the relevant OACC are lost at any time after receiving and acknowledging a clearance then the aircraft must adhere strictly to the routing and profile of the last acknowledged clearance until exiting the NAT region. Flight crews must not revert to their filed flight plan.

    Operational Procedures following Loss of HF Communications Prior to Entry into the NAT

    On-Board HF Communications Equipment Failure

    [NAT Doc 007, ¶6.6.17] Due to the potential length of time in oceanic airspace, it is strongly recommended that a flight crew, experiencing an HF communications equipment failure prior to entering the NAT, while still in domestic airspace and still in VHF contact with the domestic ATC Unit, does not enter NAT airspace but adopts the procedure specified in the appropriate domestic AIP and lands at a suitable airport. Should the flight crew, nevertheless, elect to continue the flight then every effort must be made to obtain an oceanic clearance and the routing, initial level and speed contained in that clearance must be maintained throughout the entire oceanic segment. Any level or speed changes required to comply with the oceanic clearance must be completed within the vicinity of the oceanic entry point.

    [NAT Doc 007, ¶6.6.18] If, however, an oceanic clearance cannot be obtained, the individual aircraft suffering radio communications equipment failure should enter oceanic airspace at the first oceanic entry point, level and speed contained in the filed flight plan and proceed via the filed flight plan route to landfall. The initial oceanic level and speed included in the filed flight plan must be maintained until landfall. Any subsequent climbs included in the filed flight plan must not be executed.

    HF Blackout

    [NAT Doc 007, ¶6.6.19] In the case of aircraft that lose ATC communications as a result of poor propagation conditions (HF Blackouts) when approaching NAT airspace through domestic airspace where ATC communications are also conducted via HF (e.g. entering the NAT through Northern Canadian airspace into the Reykjavik OCA), it is probably less advisable to execute unscheduled landings. These poor propagation conditions are very likely to affect many aircraft simultaneously and multiple diversions of “lost comms” aircraft might create further difficulties and risks.

    [NAT Doc 007, ¶6.6.20] As with the equipment failure situation, aircraft approaching the NAT and losing ATC communications as a result of poor HF radio propagation conditions should, if already in receipt of an oceanic clearance, follow the routing specified in that clearance and maintain the initial cleared level and speed throughout the oceanic segment i.e. through to landfall.

    [NAT Doc 007, ¶6.6.21] However, in these HF Blackout circumstances, if no oceanic clearance has been received, the aircraft must remain at the last cleared domestic flight level, not only to the ocean entry point but also throughout the whole subsequent oceanic segment (i.e. until final landfall). This is in stark contrast to the equipment failure case. In such HF Blackouts, flight crews must not effect level changes to comply with filed flight plans. Such aircraft should, maintain the last cleared level and, enter oceanic airspace at the first oceanic entry point and speed contained in the filed flight plan, then proceed via the filed flight plan route to landfall.

    [NAT Doc 007, ¶6.6.22] The rationale here must be appreciated. In such circumstances it is likely that ATC will have simultaneously lost HF communications with multiple aircraft in the same vicinity. Should flight crews then wrongly apply the “normal” radio failure procedures and “fly the flight plan”, there is a possibility that two such aircraft may have filed conflicting flight paths/levels through the subsequent oceanic airspace, and without communications with either aircraft, ATC would then be unable to intervene to resolve the conflict. Since safe aircraft level separation assurance has already been incorporated into the current domestic clearances, it is consequently imperative that under such (domestic and oceanic) HF-blackout circumstances, all aircraft electing to continue flight into NAT oceanic airspace without a received and acknowledged oceanic clearance, should adhere to the flight level in the last received domestic clearance. No level changes should be made to comply with a filed oceanic level that is different from that of the domestic clearance in effect at the time that ATC air-ground communications were lost.

    Operational Procedures following Loss of HF Communications after Entering the NAT

    [NAT Doc 007, ¶6.6.23] If the HF communications equipment failure occurs or HF Blackout conditions are encountered after entering the NAT then : -

    The flight crew must proceed in accordance with the last received and acknowledged oceanic clearance, including level and speed, to the last specified oceanic route point (normally landfall). After passing this point, the flight crew should conform with the relevant AIP specified State procedures/regulations and if necessary rejoin the filed flight plan route by proceeding, via the published ATS route structure where possible, to the next significant point contained in the filed flight plan. Note: the relevant State procedures/regulations to be followed by an aircraft in order to rejoin its filed flight plan route are specified in detail in the appropriate State AIP.

    [NAT Doc 007, ¶6.6.24] Aircraft with a destination within the NAT region should proceed to their clearance limit and follow the ICAO standard procedure to commence descent from the appropriate designated navigation aid serving the destination aerodrome at, or as close as possible to, the expected approach time. Detailed procedures are promulgated in relevant State AIPs.

    Summary of Operational Procedures Required following Loss of Air/Ground ATS Communications in the NAT Region

    [NAT Doc 007, ¶6.6.25] The foregoing detailed operational procedures can be simply summarised as follows:

    • Equipment Failure before receiving an oceanic clearance:- Divert or fly the flight plan route, speed and initial planned oceanic level to landfall.
    • Blackout encountered (in an HF comms Domestic ATC environment) before receiving an oceanic clearance:- Continue at Domestic cleared level and follow flight planned route and speed to landfall.
    • Equipment Failure or Blackout after receiving an oceanic clearance:- Fly that clearance to landfall.

    In all cases, after landfall rejoin, or continue on, the flight planned route, using appropriate State AIP specified procedures for the domestic airspace entered.

    These are exceptions to ICAO Lost Comm procedures.

    More about this: Lost Communications.

    Strategic Lateral Offset Procedure (SLOP)

    [NAT Doc 007, ¶8.5.10] Distributing aircraft laterally and equally across the three available positions adds an additional safety margin and reduces collision risk. SLOP is now a standard operating procedure for the entire NAT Region and pilots are required to adopt this procedure as is appropriate. In this connection, it should be noted that:

    1. Aircraft without automatic offset programming capability must fly the centreline.
    2. If you have automatic offset programming capability, you MUST SLOP in the North Atlantic. If you do not have automatic offset programming capability, you MAY NOT SLOP.

    3. To achieve an equal distribution of flying the centreline or 1 NM (one nautical mile) right or 2 NM (two nautical miles) right of centerline, it is recommended that pilots of aircraft capable of programming automatic offsets should randomly select flying centreline or an offset. (See Note in 8.5.2 a) above) In order to obtain lateral spacing from nearby aircraft (i.e. those immediately above and/or below), pilots should use whatever means are available (e.g. ACAS/TCAS, communications, visual acquisition, GPWS) to determine the best flight path to fly.
    4. An aircraft overtaking another aircraft should offset within the confines of this procedure, if capable, so as to create the least amount of wake turbulence for the aircraft being overtaken.
    5. For wake turbulence purposes, pilots should fly one of the three positions shown above. Pilots should not offset to the left of centreline nor offset more than 2 NM right of centreline. Pilots may contact other aircraft on the air-to-air channel, 123.45 MHz, as necessary; to coordinate the best wake turbulence mutual offset option. (Note. It is recognized that the pilot will use his/her judgement to determine the action most appropriate to any given situation and that the pilot has the final authority and responsibility for the safe operations of the aeroplane. See also Chapter 13, paragraph 13.5.) As indicated below, contact with ATC is not required.
    6. Pilots may apply an offset outbound at the oceanic entry point and must return to centreline prior to the oceanic exit point unless otherwise authorized by the appropriate ATS authority or directed by the appropriate ATC unit.
    7. Aircraft transiting ATS Surveillance-controlled airspace mid-ocean should remain on their already established offset positions.
    8. There is no ATC clearance required for this procedure and it is not necessary that ATC be advised.
    9. Voice Position reports should be based on the waypoints of the current ATC clearance and not the offset positions.
    10. Aircraft shall not apply SLOP below F285 in the Reykjavik CTA.

    If you have automatic offset capability, SLOP is mandatory for you in the North Atlantic.

    More about this: Strategic Lateral Offset Procedure (SLOP).

    See Also

    Airspace: North Atlantic High Level Airspace (NAT HLA)

    Oceanic Clearance

    Book Notes

    Portions of this page can be found in the book International Operations Flight Manual, Part III, Chapter 7.

    References

    ICAO Doc 7030 - Regional Supplementary Procedures, International Civil Aviation Organization, 2008

    ICAO Doc 7030, Amendment 1, International Civil Aviation Organization, 8 January 2009

    ICAO Doc 7030, Amendment 9, International Civil Aviation Organization, 2 October 2017

    Jeppesen Airway Manual

    ICAO NAT Doc 007, North Atlantic Operations and Airspace Manual, v 2018-1

    Revision: 20190224
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