Class FasDatablock

FAS Data Block - Encoder and Decoder for SBAS and GBAS

Inheritance

object

BaseObject

BaseObjectFasDataBlock

FasDatablock

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: FpAssistantCore.GeneralAviation

Assembly: FpAssistantCoreScl.dll

Syntax

public class FasDatablock : BaseObjectFasDataBlock

Properties

AirportIdentifier

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

Declaration

public string AirportIdentifier { get; set; }

Property Value

Type	Description
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

Exceptions

Type	Condition
ArgumentNullException	Null Value tried to be assigned
ArgumentException	Airport Identifier may only consist of 3 to 4 alphanumeric characters

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

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

Exceptions

Type	Condition
ArgumentOutOfRangeException	Course width at THR must have a value between 80m and 143.75m
ArgumentException	Course width must be in Metres

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.

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

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

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

GbasApproachPerformanceDesignator

GBAS Approach Performance Designator

Declaration

public GbasApproachPerformanceDesignators GbasApproachPerformanceDesignator { get; set; }

Property Value

Type	Description
GbasApproachPerformanceDesignators	Value of GBAS approach performance designator

Exceptions

Type	Condition
InvalidOperationException	This property is only valid for GBAS block types

GbasOperationType

Holds the type of operation for the GBAS procedure

Declaration

public GbasOperationTypes GbasOperationType { get; set; }

Property Value

Type	Description
GbasOperationTypes	GBAS operation type

Exceptions

Type	Condition
InvalidOperationException	This property is only valid for GBAS block types.

See Also

GbasOperationTypes

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

Exceptions

Type	Condition
ArgumentOutOfRangeException	Glide Path Angle must be between 0 and 90 degrees

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

Exceptions

Type	Condition
ArgumentException	Horizontal alert limit must be in Metres
ArgumentOutOfRangeException	Horizontal alert limit must have a value between 0m and 50.8m

LengthOffset

Distance from the stop end of the runway to the FPA

Declaration

public LinearDistance? LengthOffset { get; set; }

Property Value

Type	Description
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

Exceptions

Type	Condition
ArgumentException	Length offset must be in Metres
ArgumentOutOfRangeException	Length offset must have a value between 0m and 2032m

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

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

Exceptions

Type	Condition
ArgumentException	LTP/FTP height must be in Metres
ArgumentOutOfRangeException	LTP/FTP height must have a value between -512m and 6041.5m

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
int	Reference path data selector (RPDS)

Remarks

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

ReferencePathIdentifier

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

Declaration

public string ReferencePathIdentifier { get; set; }

Property Value

Type	Description
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

Exceptions

Type	Condition
ArgumentNullException	Null Value tried to be assigned
ArgumentException	Reference Path Identifier may only consist of 0 to 4 alphanumeric characters

RouteIndicator

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

Declaration

public string RouteIndicator { get; set; }

Property Value

Type	Description
string	A single alpha character

Remarks

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

Exceptions

Type	Condition
ArgumentNullException	Null passed for any of the parameters
ArgumentException	Route Indicator must consist only of a single alphabetical letter excluding I and O

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)

RunwayNumber

The approach runway number

Declaration

public int RunwayNumber { get; set; }

Property Value

Type	Description
int	Runway number

Remarks

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

SbasApproachPerformanceDesignator

SBAS Approach Performance Designator

Declaration

public SbasApproachPerformanceDesignators SbasApproachPerformanceDesignator { get; set; }

Property Value

Type	Description
SbasApproachPerformanceDesignators	Value of SBAS approach performance designator

Exceptions

Type	Condition
InvalidOperationException	This property is only valid for SBAS block types

SbasOperationType

Holds the type of operation for the SBAS procedure

Declaration

public SbasOperationTypes SbasOperationType { get; set; }

Property Value

Type	Description
SbasOperationTypes	SBAS operation type

Exceptions

Type	Condition
InvalidOperationException	This property is only valid for SBAS block types.

See Also

SbasOperationTypes

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

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

Exceptions

Type	Condition
ArgumentException	TCH height must be in Metres or Feet
ArgumentOutOfRangeException	TCH height must have a value between 0 and 1638.35m/3276.7ft

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

Exceptions

Type	Condition
ArgumentException	Vertical alert limit must be in Metres
ArgumentOutOfRangeException	Vertical alert limit must have a value between 0m and 50.8m

Methods

AsHexString(byte[])

Declaration

public string AsHexString(byte[] block)

Parameters

Type	Name	Description
byte[]	block

Returns

Type	Description
string

CrcChecksum()

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

Declaration

public byte[] CrcChecksum()

Returns

Type	Description
byte[]	Byte array of the 32-bit CRC calculated value (4 bytes)

DecodeDatablock(byte[])

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

Declaration

public bool DecodeDatablock(byte[] dataBlock)

Parameters

Type	Name	Description
byte[]	dataBlock	Byte array of the database block to be decoded into parameters

Returns

Type	Description
bool	True is successful, otherwise false

EncodeDatablock()

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

Declaration

public byte[] EncodeDatablock()

Returns

Type	Description
byte[]	Data block with last 4 bytes including the 32-bit CRC calculated value