Chapter 8. CommunicationGeneral Earlier we mentioned that VHF radio coverage is very limited in the NAT. Charts 2 and 3, (pages 23 and 24), depict theoretical VHF coverage at FL100 and FL200. Since the coverage is so limited, IT IS REQUIRED THAT YOU HAVE AN HF TRANSCEIVER ON YOUR AIRCRAFT. Radio equipment should be tested prior to departure. For VHF equipment this is best done by calling the tower or ACC on the proper frequency for a ground radio check. HF equipment shall be tested by calling the nearest Aeronautical Radio or Flight Service Station for a ground radio check. If a contact cannot be made on the initial test frequency, try others. If no contact can be made, have your equipment checked. Do not leave the ground until everything is working satisfactorily. Pilots should be aware that on most occasions when they communicate with Oceanic Air Traffic Control Centers on HF and, on rare occasions VHF, they do not talk directly to controllers. Radio Communicator staff, i.e., Aeronautical Radio Inc. (ARINC) or an international flight service station (IFSS), relay incoming messages and may not always be co-located with an ACC. For example, Shanwick Radio is in the Republic of Ireland while Shanwick Control is based at Prestwick, Scotland. Also, it is important to mention that controller workload on low level IGA flights is usually high, so expect a short delay to your request for a change of flight level, route, etc. An HF SELCAL device will ease the strain of a continuous listening watch on the designated HF R/T Frequency, Ensure the SELCAL code selected in the aircraft is valid for the Fight Information Region(s) in which you plan to fly. Remember, if you operate above FL060 you must operate under IFR procedures and therefore you must maintain a continuous listening watch with ATC. IF NOT IN VHF COVERAGE, IT IS YOUR RESPONSIBILITY TO HAVE A SERVICEABLE HF. Contingencies Although HF coverage exists throughout the NAT, there are a few associated problems. Depending on atmospheric conditions, it can be relatively noisy with the signal fading in and out. Sometimes several attempts are required to successfully transmit or receive a single message. Additionally, sunspot activity can completely disrupt HF communications for considerable periods of time, varying from a few minutes to several hours. Notices are published whenever disruptive sunspot activity is expected. You may be able to relay VHF or UHF communications through other aircraft operating in the NAT. 131.8 MHz should be used for air-to-air communications. Do not plan to use other aircraft as your primary means of communication. There is no guarantee there will be another aircraft within range when you need it. Consider this an emergency procedure and plan accordingly. VHF radios for North Atlantic crossings shall include 121.5 MHz capability. A listening watch should be maintained on this frequency unless communications on another frequency prevents it. 121.5 MHz is not authorized for routine use. NOTE-
Position Reporting Unless otherwise authorized by ATC, predominantly North/South NAT flights shall make position reports on the appropriate frequencies at each significant point listed in the flight plan. Eastbound and westbound flights are required to report at every 10 degrees of longitude. Position reports are to be forwarded to air traffic control at least at approximately hourly intervals. However, in the event of low ground speed a position report may be required every 5 degrees of longitude. Where the position relates to geographical coordinates, the contents of the position report shall be expressed by the latitude and longitude. For generally eastbound or westbound aircraft, latitude is to be expressed in degrees and minutes, longitude in degrees only. For generally northbound or southbound aircraft, latitude is to be expressed in degrees only, longitude in degrees and minutes. The pilot is required to identify the subsequent position to report as the significant point at which the aircraft is next required to report its position. The next succeeding reporting point along the route of flight is also to be included. If the estimated time over the next significant point is found to be in error by 3 minutes or more, a revised estimated time shall be transmitted to the appropriate ATC unit as soon as possible. When making position reports all times are to be expressed in UTC, giving both the hour and minutes. A position report example follows: POSITION--N1234D 53 NORTH 25 WEST 1237, FLIGHT LEVEL 090, ESTIMATE 53 NORTH 20 WEST 1356, NEXT 53 NORTH 15 WEST" The relevant AIPs contain detailed information concerning communication while operating in the NAT. Common Procedures for Radio Communications Failure The following procedures are intended to provide general guidance for NAT aircraft experiencing a communications failure. These procedures/regulations are intended to complement and not supersede State procedures/regulations. It is not possible to provide guidance for all situations associated with communications failure. General If so equipped, the pilot of an aircraft experiencing a two-way radio communications failure shall operate the secondary radar transponder identity Mode A, Code 7600, and Mode C. The pilot shall also 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 communications are intended. Communications failure prior to entering NAT oceanic airspace If operating with a received and acknowledged oceanic clearance, the pilot shall enter oceanic airspace at the cleared oceanic entry point, level and speed and proceed in accordance with the received and acknowledged oceanic clearance. Any level or speed changes required to comply with the oceanic clearance shall be completed within the vicinity of the oceanic entry point. If operating without a received and acknowledged oceanic clearance, the pilot shall enter oceanic airspace at the first oceanic entry point, level and speed, as contained in the filed flight plan and proceed via the filed flight plan route to landfall. That first oceanic level and speed shall be maintained to landfall. Communications failure prior to exiting NAT oceanic airspace Cleared on flight plan route The pilot shall proceed in accordance with the last received and acknowledged oceanic clearance to the last specified oceanic route point, normally landfall, then continue on the flight plan route. Maintain the last assigned oceanic level and speed to landfall. After passing the last specified oceanic route point, conform with the relevant State procedures/regulations. Cleared on other than flight plan route The pilot shall proceed in accordance with the last received and acknowledged oceanic clearance, normally landfall. After passing this point, rejoin the filed flight plan route by proceeding directly to the next significant point ahead of the track of the aircraft as contained in the filed flight plan. Where possible use published ATS route structures, then continue on the flight plan route. Maintain the last assigned oceanic level and speed to the last specified oceanic route point. After passing this point conform with the relevant State procedures/regulations. Chart #2
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Chart #3
NOTE 1: The VHF cover depicted in the transition area between the NAT and the EUR Regions has only been shown to complete the picture of the communication cover. The VHF air/ground communication stations at Stavanger, Scottish, London, Brest, Bordeaux, and Lisboa do not form part of the communication system serving the NAT Region. NOTE 2: The VHF cover provided by the Qaqatoqaq and Kulusuk stations in Greenland (Sondrestrom) serves Sondrestrom FIC only (below FL195). Chart #4
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| Chapter 9, Surveillance |
