PART 1......................................................................................................................................................................... 1-1 1. CONCEPTS AND DEFINITION OF THE AIRSPACE WITHIN THE NAT REGION ............................ 1-1 1.1 Airspaces Within the NAT Region 1.2 Required Navigation Performance ................................................................................................................1-2 1.3 The MNPS Concept ......................................................................................................................................1-2 1.4 MNPS Operations .........................................................................................................................................1-2 1.5 Minimum Aircraft System Performance Specification ..................................................................................1-3 1.6 Flight at RVSM Levels 1.7 Carriage and Operation of Pressure-Altitude Reporting SSR Transponders .................................................1-4 1.8 Carriage and Operation of Airborne Collision Avoidance System (ACAS) II ..............................................1-4 1.9 Use of an Air-to-Air Frequency 1.10 Use of Satellite Communications (SATCOM) ..............................................................................................1-5 1.11 Time Keeping 1.12 The Route Structure ......................................................................................................................................1-5 Characteristics of the Airspace .....................................................................................................................1-5 The Organized Track System The Polar Track Structure ............................................................................................................................1-7 1.13 Other Routes and Route Structures Within or Adjacent to NAT MNPS.......................................................1-7 General .........................................................................................................................................................1-7 Routes for Aircraft With only One Long Range Navigation System (LRNS).................................................1-7 The West Atlantic Route System ....................................................................................................................1-8 Supersonic Transport Route Structure ..........................................................................................................1-8 Routes for Aircraft with Short Range Navigation Equipment only ...............................................................1-8