Guidance concerning Air Navigation in and above the NAT MNPSA
Maintenance of a high standard of navigation performance is absolutely essential to the
maintenance of safety in the NAT MNPS Airspace.
Presentation of Navigation Information
A significant proportion of navigation errors result from the use of incorrect data. To
minimize the problem, source data must be clearly legible under the worst cockpit lighting conditions and presented in a format suitable for error-free use in the cockpit environment. In this context, the following
on navigation charts, all position co-ordinates, e.g. ramp position, ATC waypoints, radio navaid positions, etc., should ideally be printed in dark blue or black numerals against a white background. Where such co-ordinates would normally appear against a locally tinted background, they should be enclosed in a white box. Absolutely no information should be overprinted on top of position co-ordinates. In situations where groups of position co- ordinates must appear in close proximity to each other, the position to which each set of co- ordinates applies should be clearly indicated by means of a leader;
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; and
it is advisable to provide pilots with a simple plotting chart of suitable scale (1 inch equals 120 NM has been used successfully on NAT routes) in order to facilitate a visual presentation of the intended route that, otherwise, is defined only in terms of navigational co- ordinates.
Importance of Accurate Time
It must be recognised that proper operation of a correctly functioning LRNS will ensure that
the aircraft follows its cleared track. ATC applies standard separations between cleared tracks and thereby assures the safe lateral separation of aircraft. However, longitudinal separations between subsequent aircraft
following the same track ETAs/ATAs at common
and between waypoints.
aircraft on intersecting Aircraft clock errors
tracks are assessed in resulting in position
of differences in time errors can
therefore lead to an that prior to entry
erosion of actual longitudinal separations between aircraft. into the NAT MNPS Airspace the time reference system
is thus vitally important be used during the flight
is accurately synchronised waypoint ATAs are always
to UTC and that referenced to this
the calculation of waypoint ETAs and the system. Many modern aircraft master clocks
reporting of (typically the
FMS) can only be MNPS flight must
reset while the aircraft is on the ground. Thus the Pre-flight Procedures for any NAT include a UTC time check and resynchronisation of the aircraft master clock. Lists of
acceptable time sources for this purpose have been promulgated by NAT ATS Provider States.
The following are examples of acceptable time standards:
GPS (Corrected to UTC) - Available at all times to those crews who can access time via approved on-board GPS (TSO-C129) equipment.
WWV - National Institute of Standards (NIST - Fort Collins, Colorado). WWV operates continually H24 on 2500, 5000, 10,000, 15,000 and 20,000 kHz (AM/SSB) and provides UTC (voice) once every minute.
NAT Doc 007