(b)
in Fields Type 5 (Description of Emergency), 15 (Route), 18 (Other Information), 19 (Supplementary Information), 20 (Alerting Search and Rescue Information), 21 (Radio Failure Information) and 22 (Amendment), whenever it is necessary to begin a new line on page copy (see Note). In such cases, the Alignment Function shall be inserted between two data elements and shall not divide an element.
Note.— Annex 10 prescribes that a line of teletypewriter copy shall not contain more than 69 characters.
Data conventions
Most of the conventions to be used in the expression of ATS data in the messages are prescribed in the field tables on pages A3-5 to A3-29, but the conventions for the expression of level, position and route data are given below.
The expression of level data
Four alternative conventions are available for the expression of level data:
(a)
“F” followed by 3 decimal numerics: indicates a Flight Level Number, i.e. Flight Level 340 is expressed as “F340”;
(b)
“S” followed by 4 decimal numerics: indicates a Standard Metric Level in tens of metres, i.e. Standard Metric Level 11 300 m (Flight Level 370) is expressed as “S1130”;
(c)
“A” followed by 3 decimal numerics: indicates altitude in hundreds of feet, i.e. an altitude of 4 500 feet is expressed as “A045”;
(d)
“M” followed by 4 decimal numerics: indicates altitude in tens of metres, i.e. an altitude of 8 100 metres is expressed as “M0810”.
The expression of position or route
The following alternative data conventions shall be used for the expression of position or route:
(a)
from 2 to 7 characters, being the coded designator assigned to an ATS route to be flown;
(b)
from 2 to 5 characters, being the coded designator assigned to an en-route point;
(c)
4 numerics describing latitude in tens and units of degrees and tens and units of minutes, followed by “N” (meaning “North”) or “S” (South), followed by 5 numerics describing longitude in hundreds, tens and units of degrees and tens and units of minutes, followed by “E” (East) or “W” (West). The correct number of numerics is to be made up, where necessary, by insertion of zeros, e.g. “4620N07805W”;
(d)
2 decimal numerics describing latitude in degrees, followed by “N” (North) or “S” (South), followed by 3 decimal numerics describing longitude in degrees, followed by “E” (East) or “W” (West). Again, the correct number of numerics is to be made up, where necessary, by insertion of zeros, e.g. “46N078W”;
(e)
2 or 3 characters being the coded identification of a navigation aid (normally a VOR), followed by 3 decimal numerics giving the bearing from the point in degrees magnetic followed by 3 decimal numerics giving the distance from the point in nautical miles. The correct number of numerics is to be made up, where necessary, by insertion of zeros, e.g. a point at 180° magnetic at a distance of 40 nautical miles from VOR “FOJ” would be expressed as “FOJ180040”.
The detail of the fields
The elements of data prescribed or permitted to be included in each type of field, together with a prescription of the conditions or options permitted, are shown on pages A3-5 to A3-29.
A key appears at the right-hand side of each of the field pages; this key permits the sequence of fields in each type of message to be followed.
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