Guidance concerning Air Navigation in and above the NAT MNPSA
periodic reports, unlike event reports, contain wind and temperature data and thereby satisfy the MET authorities requirements for the provision of MET data. Similarly, “FMC Waypoint position reports” sent via datalink also include wind and temperature data and aircraft participating in such a datalink programme are deemed to meet the MET authorities requirements. However, it must be appreciated that any such automated MET Reports do not include information on any turbulence or any other unusual meteorological phenomena. Therefore any pilot providing position reports via datalink, who encounters turbulence, etc, should report this information via voice or, if appropriate, via a CPDLC free text downlink message.
HF COMMUNICATIONS FAILURE
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.
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 primarily 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.
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.
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. Notwithstanding the gradual introduction of Datalink and SATCOM Voice for regular air-ground ATS communications in the NAT Region, all pilots 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.
communications with ATC, conditions are encountered.
Hence, even if using
other than HF for regular caution when HF blackout
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.
The pilot of an aircraft experiencing a two-way ATS communications failure should operate the SSR Transponder on identity Mode A Code 7600 and Mode C.
When so equipped, an aircraft should use Satellite Voice Communications to contact the responsible aeradio station via special telephone numbers/short codes published in State AIPs
NAT Doc 007