Guidance concerning Air Navigation in and above the NAT MNPSA
For a flight plan received from an aircraft in flight, total estimated elapsed time starts from the first point of the route to which the flight plan applies.
Alternate Aerodrome(s) (4 characters)
Insert the ICAO four-letter location indicator(s) of not more than two alternate aerodromes, SEPARATED BY A SPACE.
If no location indicator has been assigned to an alternate aerodrome insert ZZZZ and specify in Item 18 the name of the aerodrome preceded by ALTN/.
The use of spurious names for unnamed fixes (typically extracted from navigation data bases) is to be avoided. In addition to being undefined the names fail to adhere to the format specified for fixes (five alphabetical characters) and so cause a syntax error in addition to the logical error. ARINC 424 type position reports are not to be used.
When specifying speeds in knots a leading zero is required if the speed is less than 1000 knots. No blank spaces are to be inserted between speed and level.
The ICAO convention for specifying latitude and longitude in flight plan related messages differs from that used by data base vendors in that the hemisphere indicators (N/S, E/W) should follow, not precede, the numeric component. Therefore specifying a position as “N60W010” represents an error.
The use of FIR designators as fix names is invalid, these designators should only be used in the EET sub-field of Item 18. Some flight plans contain such designators in Item 15 to indicate the transition between two FIRs at an unnamed fix. This is a syntax error. The latitude and longitude should be used.
Field 18: Other Information
Insert the following information, in the preferred sequence shown below, which should always be included for North Atlantic flights. Additional information, as contained in ICAO Doc. 4444, appendix 3, may be included as appropriate.
Note: The preface to the description of this Item in ICAO Doc. 4444 specifically states that only those sub- fields for which there is data to report should be included in Item 18. A sub-field header with no content constitutes a syntax error and will fail automatic processing.
Followed by waypoints or FIR Boundary designators plus accumulated estimated elapsed times from take-off to such points.
For flights conducted in the NAT Region on random routes, accumulated estimated elapsed times will be required for:
The last domestic reporting point prior to ocean entry.
The oceanic entry point.
Each significant point described in Item 15. (see note 2)
The oceanic exit point.
The first reporting point on the domestic track.
NAT Doc 007