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Class FasDatablock

FAS Data Block - Encoder and Decoder for SBAS and GBAS

Inheritance
System.Object
BaseObject
FpAssistantCore.GeneralAviation.BaseObjectFasDataBlock
FasDatablock
Namespace: FpAssistantCore.GeneralAviation
Assembly: FpAssistantCoreScl.dll
Syntax
public class FasDatablock : BaseObjectFasDataBlock

Properties

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AirportIdentifier

The three- or four-letter designator used to designate an airport

Declaration
public string AirportIdentifier { get; set; }
Property Value
Type Description
System.String

Airport identifier

Remarks

The four-character ICAO location identifier assigned to an airport. Where there is a national airport identifier but no ICAO location identifier, the three- or four-character national identifier is used

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BlockType

Holds the type of the FAS data block

Declaration
public BlockTypes BlockType { get; set; }
Property Value
Type Description
BlockTypes

The type of the data block

Remarks

Can be assigned to a type when encoding to create a data block or will be assigned when decoding a data block file or byte array

See Also
BlockTypes
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CourseWidthTHR

Semi-width (in metres) of the lateral course width at the LTP/FTP

Declaration
public LinearDistance CourseWidthTHR { get; set; }
Property Value
Type Description
LinearDistance

Angle of the glide path

Remarks

Angle of the FAS path with respect to the horizontal plane tangent to the WGS-84 ellipsoid at the LTP/FTP

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DeltaFpap

Difference of latitude/longitude of the runway FPAP from the LTP/FTP

Declaration
public GeoCoordinate DeltaFpap { get; set; }
Property Value
Type Description
GeoCoordinate

Delta FPAP latitude/longitude as a GeoCoordinate

Remarks

Positive value denotes the FPAP latitude north of LTP/FTP latitude/longitude east of LTP/FTP longitude. Negative value denotes the FPAP latitude south of the LTP/FTP latitude/longitude west of LTP/FTP longitude.

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DeltaFpapLatitude

Difference of latitude of the runway FPAP from the LTP/FTP

Declaration
public Angle DeltaFpapLatitude { get; set; }
Property Value
Type Description
Angle

Delta FPAP Latitude

Remarks

Positive value denotes the FPAP latitude north of LTP/FTP latitude. Negative value denotes the FPAP latitude south of the LTP/FTP latitude

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DeltaFpapLongitude

Difference of longitude of the runway FPAP from the LTP/FTP

Declaration
public Angle DeltaFpapLongitude { get; set; }
Property Value
Type Description
Angle

Delta FPAP Longitude

Remarks

Positive value indicates the FPAP longitude east of LTP/FTP longitude. Negative value indicates the FPAP longitude west of LTP/FTP longitude

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Fpap

Flight path alignment point (FPAP)

Declaration
public GeoCoordinate Fpap { get; set; }
Property Value
Type Description
GeoCoordinate

Geo coordinate of FPAP position

Remarks

A point located on a geodesic line or an extension of a geodesic line calculated between the LTP and the designated centre of the opposite runway-landing threshold

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GbasApproachPerformanceDesignator

GBAS Approach Performance Designator

Declaration
public GbasApproachPerformanceDesignators GbasApproachPerformanceDesignator { get; set; }
Property Value
Type Description
GbasApproachPerformanceDesignators

Value of GBAS approach performance designator

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GbasOperationType

Holds the type of operation for the GBAS procedure

Declaration
public GbasOperationTypes GbasOperationType { get; set; }
Property Value
Type Description
GbasOperationTypes

GBAS operation type

See Also
GbasOperationTypes
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GlidePathAngle

Glide Path Angle (GPA) of the FAS path

Declaration
public Angle GlidePathAngle { get; set; }
Property Value
Type Description
Angle

Angle of the glide path

Remarks

Angle of the FAS path with respect to the horizontal plane tangent to the WGS-84 ellipsoid at the LTP/FTP

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HorizontalAlertLimit

Horizontal Alert Limit (HAL)

Declaration
public LinearDistance HorizontalAlertLimit { get; set; }
Property Value
Type Description
LinearDistance

Radius of the circle (HAL)

Remarks

The HAL is the radius of a circle in the horizontal plane, with its centre being at the true position, that describes the region which is required to contain the indicated horizontal position with the required probability for a particular navigation mode assuming the probability of a GPS satellite integrity failure being included in the position solution is less than or equal to 10–4 per hour. The range of values is 0 to 50.8m with a 0.2m resolution. The HAL, for LPV procedures, is a fixed value at 40.0m

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LengthOffset

Distance from the stop end of the runway to the FPA

Declaration
public LinearDistance? LengthOffset { get; set; }
Property Value
Type Description
System.Nullable<LinearDistance>

Length offset distance

Remarks

It defines the location where lateral sensitivity changes to the missed approach sensitivity. The value is in metres with the limits being 0 to 2032 m. The actual distance is rounded up to the nearest value divisible by 8. If the FPAP is located at the designated centre of the opposite runway end, the distance is zero. For offset procedures, the Δ length offset is coded as zero

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LtpFtp

Landing threshold point (LTP)/Fictitious threshold point (FTP)

Declaration
public GeoCoordinate LtpFtp { get; set; }
Property Value
Type Description
GeoCoordinate

Geo coordinate of LTP / FTP position

Remarks

Represents the latitude and longitude of the threshold defined in WGS-84 coordinates and entered to five ten thousandths of an arc second

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LtpFtpHeight

LTP/FTP height relative to the ellipsoid (HAE)

Declaration
public LinearDistance LtpFtpHeight { get; set; }
Property Value
Type Description
LinearDistance

Height

Remarks

The height expressed in metres referenced to the WGS-84 ellipsoid

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ReferencePathDataSelector

The numeric identifier that is used to select the FAS data block (desired approach)

Declaration
public int ReferencePathDataSelector { get; set; }
Property Value
Type Description
System.Int32

Reference path data selector (RPDS)

Remarks

This field is reserved for use by GBAS and is not used by SBAS

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ReferencePathIdentifier

The three or four alphanumeric characters used to uniquely designate the reference path

Declaration
public string ReferencePathIdentifier { get; set; }
Property Value
Type Description
System.String

Reference path identifier

Remarks

A four-character identifier that is used to confirm selection of the correct approach procedure. For circling only procedures, the two digit runway number should be encoded as the procedure final approach course rounded to the nearest 10° and truncated to two characters

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RouteIndicator

Used to differentiate between multiple approaches to the same runway or heliport

Declaration
public string RouteIndicator { get; set; }
Property Value
Type Description
System.String

A single alpha character

Remarks

Must be A to Z or blank, omitting I and O

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RunwayLetter

Runway one-letter designator

Declaration
public RunwayLetters RunwayLetter { get; set; }
Property Value
Type Description
RunwayLetters

Runway letter designator

Remarks

Coding: 0 = no letter, 1 = R (right), 2 = C (centre), 3 = L (left)

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RunwayNumber

The approach runway number

Declaration
public int RunwayNumber { get; set; }
Property Value
Type Description
System.Int32

Runway number

Remarks

Coding: 0 = Heliport, 1 to 36 = runway number

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SbasApproachPerformanceDesignator

SBAS Approach Performance Designator

Declaration
public SbasApproachPerformanceDesignators SbasApproachPerformanceDesignator { get; set; }
Property Value
Type Description
SbasApproachPerformanceDesignators

Value of SBAS approach performance designator

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SbasOperationType

Holds the type of operation for the SBAS procedure

Declaration
public SbasOperationTypes SbasOperationType { get; set; }
Property Value
Type Description
SbasOperationTypes

SBAS operation type

See Also
SbasOperationTypes
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SbasProviderIdentifier

Holds the service provider identifier for the SBAS procedure

Declaration
public SbasProviderIdentifiers SbasProviderIdentifier { get; set; }
Property Value
Type Description
SbasProviderIdentifiers

Service provider identifier

Remarks

A number from 0 to 15 that associates the approach procedure to a particular satellite-based approach system service provide

See Also
SbasProviderIdentifiers
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ThresholdCrossingHeight

Threshold Crossing Height (TCH)

Declaration
public LinearDistance ThresholdCrossingHeight { get; set; }
Property Value
Type Description
LinearDistance

Geo coordinate of FPAP position

Remarks

The height of the FAS path above the LTP/FTP defined in either feet or metres as indicated by the TCH units selector

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VerticalAlertLimit

Vertical Alert Limit (VAL)

Declaration
public LinearDistance VerticalAlertLimit { get; set; }
Property Value
Type Description
LinearDistance

Half the length of a segment

Remarks

VAL is half the length of a segment on the vertical axis, with its centre being at the true position, that describes the region which is required to contain the indicated vertical position with a probability of 1.0  10–7 per approach, assuming the probability of a GPS satellite integrity failure being included in the position solution is less than or equal to 10–4 per hour. The range of values is 0 to 50.8m with a 0.2m resolution

Methods

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AsHexString(Byte[])

Declaration
public string AsHexString(byte[] block)
Parameters
Type Name Description
System.Byte[] block
Returns
Type Description
System.String
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CrcChecksum()

Computes the CRC checksum value based on the parameters of the FAS object

Declaration
public byte[] CrcChecksum()
Returns
Type Description
System.Byte[]

Byte array of the 32-bit CRC calculated value (4 bytes)

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DecodeDatablock(Byte[])

Encodes a data block array property based on values assigned in properties

Declaration
public bool DecodeDatablock(byte[] dataBlock)
Parameters
Type Name Description
System.Byte[] dataBlock

Byte array of the database block to be decoded into parameters

Returns
Type Description
System.Boolean

True is successful, otherwise false

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EncodeDatablock()

Encodes a data block array property based on values assigned in properties

Declaration
public byte[] EncodeDatablock()
Returns
Type Description
System.Byte[]

Data block with last 4 bytes including the 32-bit CRC calculated value

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