World Air Ops | NAT | Doc 007 MNPS Guidance

Guidance concerning Air Navigation in and above the NAT MNPSA CHAPTER 88.1.13 Maintenance of a high standard of navigation performance is absolutely essential to themaintenance of safety in the NAT MNPS Airspace.8.2 GENERAL PROCEDURESPresentation of Navigation Information8.2.1 A significant proportion of navigation errors result from the use of incorrect data. Tominimize the problem, source data must be clearly legible under the worst cockpit lighting conditions andpresented in a format suitable for error-free use in the cockpit environment. In this context, the followingconsiderations apply:a) on navigation charts, all position co-ordinates, e.g. ramp position, ATC waypoints, radionavaid positions, etc., should ideally be printed in dark blue or black numerals against awhite background. Where such co-ordinates would normally appear against a locally tintedbackground, they should be enclosed in a white box. Absolutely no information should beoverprinted on top of position co-ordinates. In situations where groups of position coordinatesmust appear in close proximity to each other, the position to which each set of coordinatesapplies should be clearly indicated by means of a leader;b) navigational documents, such as track messages or flight plans, should be double-spaced or"boxed", to minimize the possibility of line slippage when the information is read; andc) it is advisable to provide pilots with a simple plotting chart of suitable scale (1 inch equals120 NM has been used successfully on NAT routes) in order to facilitate a visualpresentation of the intended route that, otherwise, is defined only in terms of navigational coordinates.Importance of Accurate Time8.2.2 It must be recognised that proper operation of a correctly functioning LRNS will ensure thatthe aircraft follows its cleared track. ATC applies standard separations between cleared tracks and therebyassures the safe lateral separation of aircraft. However, longitudinal separations between subsequent aircraftfollowing the same track and between aircraft on intersecting tracks are assessed in terms of differences inETAs/ATAs at common waypoints. Aircraft clock errors resulting in position report time errors cantherefore lead to an erosion of actual longitudinal separations between aircraft. It is thus vitally importantthat prior to entry into the NAT MNPS Airspace the time reference system to be used during the flightis accurately synchronised to UTC and that the calculation of waypoint ETAs and the reporting ofwaypoint ATAs are always referenced to this system. Many modern aircraft master clocks (typically theFMS) can only be reset while the aircraft is on the ground. Thus the Pre-flight Procedures for any NATMNPS flight must include a UTC time check and resynchronisation of the aircraft master clock. Lists ofacceptable time sources for this purpose have been promulgated by NAT ATS Provider States.8.2.3 The following are examples of acceptable time standards:• GPS (Corrected to UTC) - Available at all times to those crews who can access time via approvedon-board GPS (TSO-C129) equipment.• WWV - National Institute of Standards (NIST - Fort Collins, Colorado). WWV operates continuallyH24 on 2500, 5000, 10,000, 15,000 and 20,000 kHz (AM/SSB) and provides UTC (voice) onceevery minute.NAT Doc 007 46 Edition 2010