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.
The VHF air-to-air frequency is 123.45 mHz.
Datalink communications are gradually being introduced into the NAT environment for position reporting and other air/ground ATXS exchanges via FANS (Future Air Navigation System) & CPDLC (Controller Pilot Data Link Communication) and also, for position reporting only, through the FMC Waypoint Position Reporting (WPR) ACARS link.
On first contact with the initial aeradio stations crews of participating aircraft should expect to receive the instruction "VOICE POSITION REPORTS NOT REQUIRED".
If datalink is used, a prior agreement is required.
Mode A 2000 with height reporting should be selected 30 minutes after entering the OCA.
In Reykjavik OCA when under radar control you may be instructed to set other squawks.
The emergency codes 7700, 7600 and 7500 are still valid in oceanic airspace.
For unrestricted operation in the MNPS Airspace an aircraft must be equipped with two fully serviceable Long Range Navigation Systems (LRNSs).
Long Range Navigation Systems may be INS, IRS/FMS or GPS.
So far as GPS is concerned, the rules are quite specific on which systems are acceptable.
Each LRNS must be capable of providing to the flight crew a continuous indication of the aircraft position relative to desired track.
A number of special routes, called Blue Spruce Routes, have been developed for aircraft equipped with only one LRNS and carrying normal short-range navigation equipment (VOR, DME, ADF).
Additional special routes designated G3 and G11 can be used by aircraft that only have VOR, DME and ADF.
These routes are within MNPS airspace and still require approval from the National Authority.
It is the responsibility of pilots with limited certification to reject clearances which would otherwise divert them from officially permitted routes.