State aviation authorities should consider limiting the validity period of approvals; and
State aviation authorities should maintain detailed records of all NAT MNPS and RVSM approvals.
Guidance concerning Air Navigation in and above the NAT MNPSA
HORIZONTAL NAVIGATION REQUIREMENTS FOR UNRESTRICTED MNPS AIRSPACE OPERATIONS
Longitudinal separations between subsequent aircraft following the same track (in-trail) and
between aircraft on intersecting tracks in the NAT MNPS Airspace are assessed in terms of differences in ATAs/ETAs at common waypoints. The longitudinal separation minima currently used in the NAT MNPS Airspace are thus expressed in clock minutes. The maintenance of in-trail separations is aided by the application of the Mach Number Technique (See Chapter 7 – “Application of Mach Number Technique”). However, aircraft clock errors resulting in waypoint ATA errors in position reports can lead to an erosion of actual longitudinal separations between aircraft. It is thus vitally important that the time-keeping device intended to be used to indicate waypoint passing times is accurate, and is synchronised to an acceptable UTC time signal before commencing flight in MNPS Airspace. In many modern aircraft, the Master Clock can only be reset while the aircraft is on the ground. Thus the pre-flight procedures for any NAT MNPS operation must include a UTC time check and resynchronisation of the aircraft Master Clock (typically the FMS). Lists of acceptable time sources for this purpose have been promulgated by NAT ATS Provider States. A non-exhaustive list is shown in Chapter 8 of this Document.
There are two navigational equipment requirements for aircraft planning to operate in MNPS
Airspace. One refers to the navigation performance that should be achieved, in terms of accuracy. The second refers to the need to carry standby equipment with comparable performance characteristics (ICAO
Annex 6, Parts I and II, Chapter 7 refer).
In terms of accuracy, an aircraft which is approved for operations within NAT MNPS
Airspace shall have a navigation performance capability such that:
the standard deviation of lateral track errors shall be less than 6.3 NM (11.7 km);
the proportion of total flight time spent by the aircraft 30 NM (56 km) or more off the
cleared track shall be less than 5.3 x 10-4;
the proportion of total flight time spent by the aircraft between 50 and 70 NM (93 and 130 km) off the cleared track shall be less than 13 x 10-5.
In most cases, Operators will be able to select equipment for which performance capability
has already been established to the satisfaction of a State of Registry. However, where a completely new navigation system is proposed for use, or where major changes have been made in the technology of an existing system, an evaluation will be necessary, to establish its quality of performance, before authorisation for use as a primary means system can follow. Currently, it has been demonstrated that the requisite accuracies may be achieved using Long Range Navigation Systems, namely INS, IRS or GNSS. Consequently, State approval of unrestricted operation in the MNPS Airspace may presently be granted to an aircraft equipped as follows:
NAT Doc 007