TWY [Taxiway [TWY]]
(ICAO) A defined path at an aerodrome/heliport established for the taxiing of aircraft/helicopters and intended to provide a link between one part of the aerodrome and another, including aircraft/helicopter stand taxilines, apron taxiways, rapid exit taxiways, air taxiways etc..
Attributes
TXT_DESIG [Designator] mandatory
The textual designator of the taxiway.
Domain: TXT_DESIG
CODE_TYPE [Type] mandatory
A code indicating the type of taxiway.
For example, normal taxiway, apron taxiway, air taxiway, etc..
Domain: CODE_TYPE_TWY
VAL_WID [Width] optional
The value of the physical width of the taxiway.
Rules:
  1. If VAL_WID is specified, then UOM_WID is mandatory.
Domain: VAL_DIST_HORZ
UOM_WID [Unit of measurement [width]] optional
The unit of measurement of the taxiway dimensions.
Domain: UOM_DIST_HORZ
[CODE_COMPOSITION] DEPRECATED-4.5 [Surface composition] optional
A code indicating the composition of the taxiway surface.
For example, asphalt, concrete etc..
Rules:
  1. If CODE_COMPOSITION is 'WATER', then CODE_COND_SFC, CODE_STRENGTH and TXT_DESCR_STRENGTH may not be specified.
Domain: CODE_COMPOSITION_SFC
[CODE_COND_SFC] DEPRECATED-4.5 [Surface condition] optional
A code indicating the condition of the taxiway surface.
Domain: CODE_COND_SFC
[CODE_STRENGTH] DEPRECATED-4.5 [Surface strength method] optional
A code indicating the method used to measure the surface strength.
Rules:
  1. If CODE_STRENGTH has the value 'PCN', then the value of TXT_DESCR_STRENGTH shall conform to the rules for the PCN-ACN method, as specified in ICAO Annex 14, item 2.6.
    Examples:
    - '80/R/B/W/T'
    - '40/ F/ B /0.80 MPa /T'
    - '50/F/A/Y/U Note: - Composite construction'
    - '50/F/A/Y/U Note: - The reported PCN is subject to a B747-400 all-up mass limitation of 390 000 kg.'
    If no method is indicated in the 'Surface strength method' field, then there are no restrictions with regard to the content of this field. For example: 'LCN 72, h= 56'.
Domain: [CODE_STRENGTH_SFC]
[TXT_DESCR_STRENGTH] DEPRECATED-4.5 [Surface strength] optional
The surface strength, in character format, according to the value of the CODE_STRENGTH attribute.
For example, 80/R/B/W/T for a PCN type value.
Domain: TXT_DESCR
CODE_STS [Operational status] optional
A code indicating the operational status of a taxiway.
For example, serviceable, unserviceable, closed, work in progress, etc.
Domain: CODE_STS_SFC
TXT_MARKING [Marking system description] optional
A textual description of the marking system on the taxiway.
Domain: TXT_DESCR
TXT_RMK [Remark] optional
Domain: TXT_RMK
TWY_CLINE_POINT [Position on the centre line of a TWY]
A position on the centre line of a taxiway.
Rules:
  1. The position given by GEO_LAT, GEO_LONG must be plausibly close (less than 20 KM) to that of the ARP of the related AD_HP.
Attributes
NO_SEQ [Sequence number] mandatory
A number indicating the order of the TWY_CLINE_POINTs making up the centre line of a TWY.
Domain: NO_SEQ
GEO_LAT [Latitude] mandatory
The latitude of the position of the centre line point.
Domain: GEO_LAT
GEO_LONG [Longitude] mandatory
The longitude of the position of the centre line point.
Domain: GEO_LONG
CODE_DATUM [Datum] mandatory
A code indicating the geodetic datum in which the geographical co-ordinates are expressed.
Rules:
  1. All geographical coordinates should be expressed in the WGS 84 system.
Domain: CODE_DATUM
VAL_GEO_ACCURACY [Geographical accuracy] optional
The horizontal distance from the stated geographical position within which there is a defined confidence of the true position falling.
Rules:
  1. If VAL_GEO_ACCURACY is specified, then UOM_GEO_ACCURACY is mandatory.
Domain: VAL_DIST_HORZ
UOM_GEO_ACCURACY [Unit of measurement [geographical accuracy]] optional
The unit of measurement for the value expressing the accuracy of the geographical co-ordinates.
Domain: UOM_DIST_HORZ
VAL_ELEV [Elevation] optional
The vertical distance of the position from Mean Sea Level. The geoidal height of the position.
Rules:
  1. If VAL_ELEV is specified, then UOM_DIST_VER is mandatory.
Domain: VAL_DIST_VER
VAL_ELEV_ACCURACY [Elevation accuracy] optional
The vertical distance from the stated elevation within which there is a defined confidence of the true position falling.
Rules:
  1. VAL_ELEV_ACCURACY may be specified only if VAL_ELEV has been specified.
Domain: VAL_DIST_VER
VAL_GEOID_UNDULATION [Geoid undulation] optional
A distance separating the geoid and the ellipsoid at that position. In respect of WGS-84 geodetic datum, the difference between the WGS-84 ellipsoidal height and geoidal height represents geoidal undulation.
Rules:
  1. VAL_GEOID_UNDULATION may be specified only if VAL_ELEV has been specified.
Domain: VAL_DIST_VER
UOM_DIST_VER [Unit of measurement [vertical distance]] optional
The unit of measurement for vertical distances: elevation, geoidal undulation.
Domain: UOM_ELEV
VAL_CRC [Cyclic redundancy check] optional
Hexadecimal value of a 32-bit polynominal cyclic redundancy check (CRC) over the values of a selected set of attributes that model critical, essential and routine data, according to ICAO Annex 15, item 3.2.10.
Notes:
Applications implementing the model shall decide and notify the specific attributes which are used for the CRC calculations, taking into consideration the requirements of the ICAO Annex 15.
Domain: VAL_HEX
TXT_VER_DATUM [Vertical Datum] optional
Attribute to take the "Vertical Datum" (viz. the tide gauge to determine MSL - for example, "AMSTERDAM GAUGE", "NEWLYN" etc.).
Domain: TXT_DESCR
TXT_RMK [Remark] optional
Domain: TXT_RMK
TWY_HOLDING_POSITION [TWY holding position]
A position on a taxiway where aircraft may hold for various reasons including navigation facility checkpoints and runway end holding positions.
Attributes
TXT_MARKING [Marking system description] optional
A textual description of the marking used to indicate the holding position on the taxiway.
Domain: TXT_DESCR
TXT_LGT [Lighting system description] optional
A textual description of the lighting used to indicate the holding position on the taxiway.
Domain: TXT_DESCR
TXT_RMK [Remark] optional
Domain: TXT_RMK
TWY_INTERSECTION [Intersection of a TWY with another TWY, RWY or FATO]
The intersection of a taxiway with another taxiway, runway or FATO.
Notes:
1. The presence of this entity in the model must be regarded just as a starting point for further work.
Rules:
  1. A taxiway may not intersect itself.
  2. A taxiway may not intersect twice the same taxiway, runway or FATO.
Attributes
TXT_RMK [Remark] optional
Domain: TXT_RMK
TWY_LGT_SYS [TWY lighting system]
... a type of
SURFACE_LGT_SYS
The lighting system provided for a taxiway at an aerodrome/heliport.
Attributes
... see as well the attributes of the super-type entity
CODE_PSN [Part] mandatory
A code indicating the part of the TWY surface the lighting system is serving.
For example, centre line, edge, etc..
Domain: CODE_PSN_TWY
UNIT [Organisation unit providing services]
A generic term meaning variously all types of 'units' providing all types of services. This includes particularly Air Traffic Management (ATM) Units but also units which are not express verbs included in ATM such as SAR, MET, COM etc. .
Rules:
  1. For every UNIT there must be at least one postal address and one telephone number defined.
Attributes
TXT_NAME [Name] mandatory
The full textual name of a 'unit'. This name must be established according to the rules specified by ICAO, viz.: in the official language of the country, transposed into the Latin Alphabet where necessary.
Notes:
Since the attribute will be formed by 'text' (meaning in free format), it might not always be possible to assure 'uniqueness'. In a first approach, the unit name as provided in the AIP will be used.
For example, Berlin ACC, Malmoe TMC.
More global solutions will have to be found.
Domain: TXT_NAME
CODE_TYPE [Type] mandatory
A code indicating the 'type' of unit available in as much detail as possible.
E.g. Approach Control Office dealing with departures only or Aeronautical Information Services Briefing Office.
Domain: CODE_TYPE_UNIT
CODE_CLASS [Classification] mandatory
A code indicating a general 'classification' of a unit.
For example, ICAO,OTHER.
Domain: CODE_CLASS_UNIT
CODE_ID [Coded Identifier] optional
A coded identifier associated with the Unit. For example, the ICAO Location Indicator of an ACC, as listed in DOC 7910.
Domain: CODE_ID_ORG
GEO_LAT [Latitude] optional
The latitude of the position where the unit is located.
Domain: GEO_LAT
GEO_LONG [Longitude] optional
The longitude of the position where the unit is located.
Domain: GEO_LONG
CODE_DATUM [Datum] optional
A code indicating the geodetic datum in which the geographical co-ordinates are expressed.
Rules:
  1. All geographical coordinates should be expressed in the WGS 84 system.
Domain: CODE_DATUM
TXT_RMK [Remark] optional
Domain: TXT_RMK
UNIT_ASSOC [Unit association]
This entity type serves to realize the different 'two-way associations' (Bill of Material, explosion-implosion) which may exist between UNITs of the same and/or different types. These associations could easily be represented as many-to-many relationships. Since there are however, quite a number of possibilities according to which the UNITs concerned are associated, this entity must have the attributes necessary to control these associations.
Examples:
a) a unit might be co-located with another one (for example, an FMP with an ACC);
b) a given unit might furnish information to another one (for example, an MWO to an ACC);
c) a unit might be dependent on another one (for example, an ACC on an RSR or a COM unit);
d) a unit might be subordinated to another one (for example, an FMP to the/a CFMU);
etc.
Rules:
  1. If a unit having CODE_TYPE='RSC' ('rescue sub-centre') is part of a subordinate association (CODE_TYPE of UNIT_ASSOC is 'SUB') with a UNIT with CODE_TYPE='RCC' ('rescue co-ordination centre') or 'SAR' ('search and rescue centre'), it takes always the role of the child.
Attributes
CODE_TYPE [Type] mandatory
A code indicating the type of association between two UNIT occurrences.
Rules:
  1. If CODE_TYPE='CL' ('co-located'), than the geographical position of the two units, if specified using the GEO_LAT and GEO_LONG attributes, have to be plausibly close (less than 5 KM).
Domain: CODE_TYPE_ASSOC_UNIT
TXT_RMK [Remark] optional
Domain: TXT_RMK
VOR [VHF omnidirectional radio range beacon [VOR]]
(ICAO) A VHF omnidirectional radio range beacon. A short-range, very-high-frequency omnidirectional beacon which provides an indication in the aircraft of the bearing of the beacon, or left-right track indication.
Attributes
CODE_ID [Identification] mandatory
The coded identification of the radio navigation aid.
Rules:
  1. CODE_ID shall not be duplicated within 600 NM of the location of the VOR (see Annex 11, Appendix 2, paragraph 2.2.2).
Domain: CODE_ID_NAV_AID
GEO_LAT [Latitude] mandatory
The latitude of the position of the VOR.
Domain: GEO_LAT
GEO_LONG [Longitude] mandatory
The longitude of the position of the VOR.
Domain: GEO_LONG
TXT_NAME [Name] optional
The full textual name of the radio navigation aid.
Domain: TXT_NAME
CODE_TYPE [Type] mandatory
A code indicating the type of VOR.
For example, conventional or Doppler.
Domain: CODE_TYPE_VOR
VAL_FREQ [Frequency] mandatory
The value of the frequency.
Rules:
  1. The value of the VAL_FREQ must be in the interval 108.000 to 117.975 MHz.
  2. The value of the VAL_FREQ must be multiple of 50 kHz (e.g. 117.950 is a correct value while 117.975 is not)
    (see ICAO Annex 10, Vol. 1, section 3.3.2.1).
Domain: VAL_FREQ
UOM_FREQ [Unit of measurement [frequency]] mandatory
The unit of measurement of the frequency.
Domain: UOM_FREQ
CODE_TYPE_NORTH [North reference] mandatory
A code indicating the direction of the 'zero bearing' provided by the station. For example: magnetic north, true north.
Domain: CODE_TYPE_NORTH
VAL_DECLINATION [Station declination] optional
The angular difference between the direction of the 'zero bearing' indicated by the station and the direction of the True North.
Domain: VAL_ANGLE_MAG_VAR
VAL_MAG_VAR [Magnetic variation] optional
The local angular difference between the True North and the Magnetic North.
Rules:
  1. If VAL_MAG_VAR is specified, then DATE_MAG_VAR is mandatory.
Domain: VAL_ANGLE_MAG_VAR
DATE_MAG_VAR [Magnetic variation date] optional
The year the magnetic variation was measured.
Domain: DATE_YEAR
CODE_EM [Emission] optional
A code indicating the type of emission, as defined at the 1979 ITU World Administrative Radio Conference.
For example, A3E, NONA2a, G1D, etc..
Domain: CODE_EM_RDO
CODE_DATUM [Datum] mandatory
A code indicating the geodetic datum in which the geographical co-ordinates are expressed.
Rules:
  1. All geographical coordinates should be expressed in the WGS 84 system.
Domain: CODE_DATUM
VAL_GEO_ACCURACY [Geographical accuracy] optional
The horizontal distance from the stated geographical position within which there is a defined confidence of the true position falling.
Rules:
  1. If VAL_GEO_ACCURACY is specified, then UOM_GEO_ACCURACY is mandatory.
Domain: VAL_DIST_HORZ
UOM_GEO_ACCURACY [Unit of measurement [geographical accuracy]] optional
The unit of measurement for the value expressing the accuracy of the geographical co-ordinates.
Domain: UOM_DIST_HORZ
VAL_ELEV [Elevation] optional
The vertical distance of the position from Mean Sea Level. The geoidal height of the position.
Rules:
  1. If VAL_ELEV is specified, then UOM_DIST_VER is mandatory.
Domain: VAL_DIST_VER
VAL_ELEV_ACCURACY [Elevation accuracy] optional
The vertical distance from the stated elevation within which there is a defined confidence of the true position falling.
Rules:
  1. VAL_ELEV_ACCURACY may be specified only if VAL_ELEV has been specified.
Domain: VAL_DIST_VER
VAL_GEOID_UNDULATION [Geoid undulation] optional
A distance separating the geoid and the ellipsoid at that position. In respect of WGS-84 geodetic datum, the difference between the WGS-84 ellipsoidal height and geoidal height represents geoidal undulation.
Rules:
  1. VAL_GEOID_UNDULATION may be specified only if VAL_ELEV has been specified.
Domain: VAL_DIST_VER
UOM_DIST_VER [Unit of measurement [vertical distance]] optional
The unit of measurement for vertical distances: elevation, geoidal undulation.
Domain: UOM_ELEV
VAL_CRC [Cyclic redundancy check] optional
Hexadecimal value of a 32-bit polynominal cyclic redundancy check (CRC) over the values of a selected set of attributes that model critical, essential and routine data, according to ICAO Annex 15, item 3.2.10.
Notes:
Applications implementing the model shall decide and notify the specific attributes which are used for the CRC calculations, taking into consideration the requirements of the ICAO Annex 15.
Domain: VAL_HEX
TXT_VER_DATUM [Vertical Datum] optional
Attribute to take the "Vertical Datum" (viz. the tide gauge to determine MSL - for example, "AMSTERDAM GAUGE", "NEWLYN" etc.).
Domain: TXT_DESCR
TXT_RMK [Remark] optional
Domain: TXT_RMK
VOR_USAGE_LIMIT [VOR usage limitation]
All limitations of the same type (such as, coverage, usability, out of tolerance, etc.) of a VOR, described using circular sector volumes.
Attributes
CODE_TYPE [Limitation type] mandatory
A code indicating the type of radio navigation aid limitation.
Rules:
  1. If CODE_TYPE='CVR' ('coverage'), then VAL_DIST_OUTER is mandatory.
  2. If CODE_TYPE='SCL' ('scalloping'), then VAL_ANGLE_SCALLOP is mandatory.
Domain: CODE_TYPE_NAV_AID_LIMIT
TXT_RMK [Remark] optional
Domain: TXT_RMK
[AIRSPACE_ASSOC] DEPRECATED-4.0 [Airspace association]
This type of entity serves to realise the different 'two-way associations' (Bill of Material, explosion-implosion) which may exist between 'airspaces' of the same and/or different types. These associations could easily be represented as many-to-many relationships. Since there are however, quite a number of 'operations' according to which the airspaces may be associated, this entity must take the attributes necessary to control these operations.
Examples:
a) an airspace may consist of any number of other airspaces;
b) an airspace may be contained within any number of other airspaces;
c) an airspace may be the intersection of or difference between any number of other airspaces;
d) an airspace may consist of any combination of the foregoing;
e) TIMETABLES related to associated AIRSPACES must not 'overlap'; etc.
Rules:
  1. An AIRSPACE that appears as child in an AIRSPACE_ASSOC with CODE_TYPE='BOM', cannot appear as child in an another AIRSPACE_ASSOC with CODE_TYPE='ABOVE-BELOW' (i.e., one AIRSPACE cannot be in the same time the result of a Bill Of Material aggregation and also being indicated as using the same horizontal border as another airspace).
  2. In any set of AIRSPACE_ASSOCIATION occurences with CODE_TYPE = 'BOM' and having the same child AIRSPACE, there must exist one and only one occurence with CODE_OPR = 'BASE'.
  3. AIRSPACE with CODE_TYPE='FIR' cannot appear as child in an AIRSPACE_ASSOCIATION of type 'BOM' or 'ABOVE-BELOW'.
Attributes
[CODE_TYPE] DEPRECATED-4.0 [Association type] mandatory
A code indicating the type of association between two AIRSPACE occurrences.
Notes:
Some values of the CODE_TYPE attribute (such as 'BOM'= Bill Of Material) are further detailed using the CODE_OPR and NO_SEQ attribute.
Rules:
  1. If CODE_TYPE = 'BOM', then CODE_OPR and NO_SEQ_OPR are mandatory. Otherwise, they cannot be specified.
Domain: [CODE_TYPE_ASSOC_AS]
[CODE_OPR] DEPRECATED-4.0 [Association operation] optional
A code used, in conjunction with attributes CODE_TYPE and NO_SEQ_OPR, to further detail some types of AIRSPACE associations.
Notes:
For example, to indicate that an airspace A results from the reunion of airspace B and C from which airspace D is subtracted, the following occurrences of the AIRSPACE_ASSOCIATION are necessary:
- B as parent, A as child, CODE_TYPE = 'BOM', CODE_OPR = 'BASE', NO_SEQ_OPR = 1;
- C as parent, A as child, CODE_TYPE = 'BOM', CODE_OPR = 'UNION', NO_SEQ_OPR = 2;
- D as parent, A as child, CODE_TYPE = 'BOM', CODE_OPR = 'SUBTR', NO_SEQ_OPR = 3.
Rules:
  1. If CODE_OPR = 'BASE', then NO_SEQ_OPR must be '1' (first).
Domain: CODE_OPR
[NO_SEQ_OPR] DEPRECATED-4.0 [Association operation order] optional
A sequence number used to indicate the order of the operations indicated by the CODE_OPR in a Bill Of Material ('BOM') airspace association.
Domain: NO_SEQ
[TXT_RMK] DEPRECATED-4.0 [Remark] optional
Domain: TXT_RMK