HF COMMUNICATIONS

Most NAT air/ground communications are conducted on single side-band HF frequencies. Pilots communicate with OACs via aeradio stations staffed by communicators who have no executive ATC authority. Messages are relayed, from the ground station to the relevant OAC for action. Aeradio stations and OACs are not necessarily co-located. For example in the case of Shanwick operations, the OAC is located at Prestwick in Scotland whilst the associated aeradio station is at Ballygirreen in the Republic of Ireland. The allocation of the families of SSB frequencies (A, B, C, D, E and F) is by State of Registry of the aircraft and according to the route to be flown. AIPs list the families to be used and additionally, the aeradio stations may advise individual aircraft as to which frequencies are to be used, after initial contact by the pilot.
 

VHF COMMUNICATIONS

The carriage of HF communications equipment is mandatory for flight in the Shanwick OCA. Aircraft with only functioning VHF communications equipment should plan their route outside the Shanwick OCA and ensure that they remain within VHF coverage of appropriate ground stations throughout the flight. Theoretical VHF coverage charts are included in ICAO NAT Doc 001, T13.5N. Details of communication requirements are published in State AIPs and ICAO publications.
 

TIME AND PLACE OF POSITION REPORTS

Unless otherwise requested by Air Traffic Control, position reports from flights on routes which are not defined by designated reporting points should be made at the significant points listed in the flight plan.

Air Traffic Control may require any flight operating in a North/South direction to report its position at any intermediate parallel of latitude when deemed necessary.

In requiring aircraft to report their position at intermediate points, ATC is guided by the requirement to have positional information at approximately hourly intervals and also by the need to cater for varying types of aircraft and varying traffic and MET conditions.

Pilots must always report to ATC as soon as possible on reaching any new cruising level.
 

CONTENTS OF POSITION REPORTS

For flights outside the PTS and domestic ATS route network, position should be expressed in terms of latitude and longitude except when flying over named reporting points. For flights whose tracks are predominantly east or west, latitude should be expressed in degrees and minutes, longitude in degrees only. For flights whose tracks are predominantly north or south, latitude should be expressed in degrees only, longitude in degrees and minutes. All times should be expressed in four digits giving both the hour and the minutes UTC.

In respect of the above, where the need to report degrees and minutes is referred to, it should be noted that when such minutes are zero then the position report may refer solely to degrees (as per examples below).

Within the PTS, the position reporting procedure is as described in Chapter 3.
 

STANDARD MESSAGE TYPES

Standard air/ground message types and formats are used within the NAT Region and are published in State AIPs and Atlantic Orientation charts. To enable ground stations to process messages in the shortest possible time, pilots should observe the following rules:

(1) use the correct type of message applicable to the data transmitted;
(2) state the message type in the contact call to the ground station or at the start of the message;
(3) adhere strictly to the sequence of information for the type of message;
(4) all times in any of the messages should be expressed in hours and minutes UTC.

The message types are shown below with examples:
 

• POSITION

• REQUEST CLEARANCE

or if a position report is not required

"Request Clearance, Speedbird 212, Request Flight Level 370"
 

• REVISED ESTIMATE

• MISCELLANEOUS

ADDRESSING OF POSITION REPORTS

Position reports made by aircraft operating within an OCA at a distance of 60 nm or less from the common boundary with an adjacent OCA, including aircraft operating on tracks through successive points on each boundary, should also be made to the ACC serving the adjacent OCA. (In practice this only requires an addition to the address. e.g. "Shanwick copy Santa Maria".)
 

"WHEN ABLE HIGHER" (WAH) REPORTS

Prior advice to ATC of the time or position that a flight will be able to accept the next higher level can assist ATC in ensuring optimal usage of available altitudes. These reports can also be used to help plan the altitudes for flights as they transition from RVSM to conventional altitudes. A WAH Report must be provided by all flights entering the MNPS Airspace portion of the New York OCA and entering the Santa Maria OCA. Provision of WAH Reports on entering other NAT OCAs is optional or they may be requested by any OAC.

When required or when otherwise provided, upon entering an oceanic FIR, pilots should include in the initial position report the time or location that the flight will be able to accept the next higher altitude. The report may include more than one altitude if that information is available.

Example: "Global Air 543, 40 North 40 West at 1010, Flight Level 350, Estimating 40 North 50 West at 1110, 40 North 60 West Next. Able Flight Level 360 at 1035, Able Flight Level 370 at 1145,Able Flight Level 390 at 1300"

Information thus provided of the aircraft’s future altitude "ability" will not automatically be interpreted by ATC as an advance "request" for a step climb. It will be used as previously indicated to assist ATC in planning airspace utilization. However, should the pilot wish to register a request for one or more future step climbs, this may be incorporated in the WAH report by appropriately substituting the word "Request" for the word "Able".

Example: "Global Air 543, 42 North 40 West at 1215, Flight Level 330, Estimating 40 North 50 West at 1310, 38 North 60 West Next. Request Flight Level 340 at 1235, Able Flight Level 350 at 1325,Request Flight Level 360 at 1415"

Although optimal use of the WAH reports is in conjunction with a Position Report, a WAH report can be made or updated separately at any time.

Example: "Global Air 543, Able Flight Level 360 at 1035, Request Flight Level 370at 1145, Able Flight Level 390 at 1300"

METEOROLOGICAL REPORTS

From among the aircraft intending to operate on the organized track system, OACs designate those which will be required to report routine meteorological observations at, and midway between, each prescribed reporting point. The designation is made by the OAC when issuing the Oceanic Clearance using the phrase "SEND MET REPORTS", and is normally made so as to designate one aircraft per track at approximately hourly intervals, unless otherwise requested by the associated MET Office. Pilots flying tracks partly or wholly off the OTS should include routine Met observations with every prescribed report. The midpoint observation should be recorded then transmitted at the next designated reporting point.
 

SELCAL

When using HF communications, pilots should maintain a listening watch on the assigned frequency, unless SELCAL is fitted, in which case they should ensure the following sequence of actions:

Twelve Tone SELCAL

Flight management staffs and crews of aircraft equipped with 12-tone SELCAL equipment should be made aware that SELCAL code assignment is predicated on the usual geographical area of operation of that aircraft. If the aircraft is later flown in geographical areas other than as originally specified by the aircraft operator, the aircraft may encounter a duplicate SELCAL code situation. Whenever an aircraft is to be flown routinely beyond the area of normal operations or is changed to a new geographic operating area, the aircraft operator should contact the SELCAL Registrar and request a SELCAL code appropriate for use in the new area.

When acquiring a previously owned aircraft equipped with SELCAL, many aircraft operators mistakenly assume that the SELCAL code automatically transfers to the purchaser or lessee. This is not true. As soon as practical, it is the responsibility of the purchaser or lessee to obtain a SELCAL code from the Registrar, or, if allocated a block of codes for a fleet of aircraft, to assign a new code from within the block of allocated codes. In the latter instance, if 12-tone equipment is involved, the Registrar should be consulted when there is any question as to the likely geographical area of operation and the possibility of code duplication.

The registrar can be contacted via the AFTN address KDCAXAAG, and by including "ATTN. OPS DEPT. (forward to SELCAL Registrar)" as the first line of message text.
 

GENERAL PURPOSE VHF COMMUNICATIONS (GP/VHF)

Aeradio stations are also responsible for the operation of GP/VHF outlets. These are especially valuable in the vicinity of Iceland, Faroes and Greenland since VHF is not as susceptible to sunspot activity as HF. Outlets are situated at Prins Christian Sund, which is remotely controlled from Gander Aeradio station, and at Qaqatoqaq, Kulusuk and the Faroes, via Iceland Radio. When using GP/VHF frequencies in areas of fringe coverage however, care should be taken to maintain a SELCAL watch on HF thus ensuring that if VHF contact is lost the aeradio station is still able to contact the aircraft. It is important for the pilot to appreciate that when using GP/VHF communications they are with an aeradio station and not by direct contact with ATC. However Direct Controller/Pilot Communications (DCPC) can be arranged if necessary on some GP/VHF frequencies.

DATA LINK COMMUNICATIONS

Data link communications are gradually being introduced into the NAT environment for position reporting. AIS publications of the NAT ATS Provider States should be consulted to determine the extent of their implementation and any associated procedures.
 

HF COMMUNICATIONS FAILURE

Each aeradio station continuously listens out on its appropriate family/families of NAT HF frequencies. In the event of failure of HF communications every effort should be made by the pilot to relay position reports through other aircraft. An air-to-air VHF frequency for the Region has been agreed; when out of range of VHF ground stations on the same or adjacent frequencies, 131.8 MHz may be used to relay position reports. If necessary initial contact for such relays can be established on 121.5 MHz - although great care must be exercised should this be necessary, as the frequency 121.5 MHz is monitored by all aircraft operating in the NAT Region, in case it is being used by aircraft experiencing emergencies. Therefore in order to minimise unnecessary use of 121.5 MHz, it is recommended that aircraft additionally monitor 131.8 MHz when flying through NAT airspace.

Solely when flying in the Shanwick OCA, pilots of aircraft which are Satellite Communications (SATCOM) equipped, who have experienced total HF failure and are unable to relay by any other means, may, as a last resort, make contact with the Shanwick HF aeradio station at Ballygirreen on the special SATCOM number shown in the UK AIP and AIP Ireland for that purpose.

The following procedures are intended to provide general guidance for aircraft operating in or proposing to operate in the NAT Region, which experience communications failure. These procedures are intended to complement and not supersede State procedures/regulations. It is impossible to provide guidance for all situations associated with a communications failure.
 

General

If so equipped, the pilot of an aircraft experiencing a two way communications failure should operate the SSR Transponder on identity Mode A Code 7600 and Mode C.

The pilot should attempt to contact any ATC facility or another aircraft and inform them of the difficulty and request they relay information to the ATC facility with whom communications are intended.
 

Communications Failure Prior to Entering NAT Region

Due to the potential length of time in oceanic airspace, it is strongly recommended that a pilot experiencing communications failure whilst still in domestic airspace does not enter the OCA but adopts the procedure specified in the appropriate domestic AIP and lands at a suitable airport. However, if the pilot elects to continue, then, to allow ATC to provide adequate separation, one of the following procedures should be followed:

Communications Failure After Entering NAT Region

If cleared on the filed flight plan route, the pilot 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) then continue on the filed flight plan route. After passing the last specified oceanic route point, the flight should conform with the relevant State procedures/regulations.

If cleared on other than the filed flight plan route, the pilot 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 pilot should conform with the relevant State procedures/regulations, rejoining 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.

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.
 

OPERATION OF TRANSPONDERS

Unless otherwise directed by ATC, pilots of aircraft equipped with SSR transponders 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 min after entry into NAT airspace. 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 recognized by the subsequent Domestic Radar Service on exit from the oceanic airspace.

Note: this procedure does not affect the use of the special purpose codes (7500, 7600 and 7700) in cases of: unlawful interference, radio failure, emergency.

It should, however, be noted that 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.
 

AIRBORNE COLLISION AVOIDANCE SYSTEMS (ACAS)

Pilots should report all ACAS Resolution Advisories which occur in the NAT Region to the controlling authority for the airspace involved.

(C) HANKE-Aviation GmbH 2014