RNAV Procedures
AIXM Procedures Seminar 1-2 Sept 2010
1
Conventional Procedure Description
• Conventional Instrument Flight Procedures
• Published in AIP
• Defined as textual descriptions supported by charts
• The charts are used by the pilots and ATC
• Recommend that AIP does not provide RNAV
interpretations of procedures not designed according to
RNAV procedure design methodology
• Data Houses and OEM best placed to interpret
requirement for individual FMS/RNAV. However,
description must be clear and unambiguous
AIXM Procedures Seminar 1-2 Sept 2010
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RNAV Procedure Description
• RNAV Instrument Flight Procedures
• Published in AIP
• Defined by unambiguous descriptions supported
by charts
• Provides Data Hobase providers require clear
and unambiguous procedure descriptions and
use the charts to validate/check
AIXM Procedures Seminar 1-2 Sept 2010
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Coding the Procedure
Procedure coding
• Translates textual description of route or a terminal procedure
into a format useable in RNAV systems.
Two steps:
• Translation from AIP text/chart into ARINC 424 alphanumeric
code
• Translation from ARINC 424 into avionic specific binary code
(known as ‘packing’)
Successful translation into ARINC 424 depends upon a
clear and unambiguous description of the
route/procedure.
AIXM Procedures Seminar 1-2 Sept 2010
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ARINC 424
•
•
•
•
•
Industry standard for the transmission of data
Navigation element uniquely defined and stored
Can be accessed for any intended navigation purpose
Developed to allow RNAV to be used on conventional procedures
ICAO PANS-OPS references ARINC 424 rules and methodologies
Note: ARINC 424 not developed for design of flight procedures,
BUT: understanding of ARINC 424 enables procedure designers
to perform their tasks so that misinterpretations and errors
are significantly reduced
AIXM Procedures Seminar 1-2 Sept 2010
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En-Route Coding
• Individual airway legs defined by waypoint and
altitude constraints
• En-route holds not associated with any aerodrome
and identified as ‘ENRT’
AIXM Procedures Seminar 1-2 Sept 2010
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Terminal Procedure Coding
• Procedure identified as SID, STAR or APCH
• Only one STAR allowed per route
• ENRT Transitions used to link STARs to APCHs.
• RWY Transitions used to link RWYs to SIDs
• Individual legs defined by heading, waypoint, waypoint
transition, path terminator, speed constraint, altitude
constraint as appropriate
AIXM Procedures Seminar 1-2 Sept 2010
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Waypoint Transitions
Fly-by
Fly-over
Radius to Fix (RF)
AIXM Procedures Seminar 1-2 Sept 2010
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RNAV – Path Terminator Leg Type
Terminator
Path
Constant DME arc
Course to
Direct Track
Course from a fix to
Holding pattern
Initial
Constant radius
Track between
Heading to
AIXM Procedures Seminar 1-2 Sept 2010
A
C
D
F
H
I
R
T
V
A
C
D
F
I
M
R
Altitude
Distance
DME distance
Fix
Next leg
Manual termination
Radial termination
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Path Terminators
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•
•
•
•
•
•
•
•
•
•
•
•
•
14 RNAV Types
Course to an Altitude
Course to a Fix
Direct to a Fix
Fix to an Altitude
Fix to a Manual Termination
Racetrack Course Reversal (Alt Term)
Racetrack (Single Circuit - Fix Term)
Racetrack (Manual Termination)
Initial Fix
Track to a Fix
Constant Radius Arc
Heading to an Altitude
Heading to an Intercept
Heading to a Manual Termination
AIXM Procedures Seminar 1-2 Sept 2010
-
CA
CF
DF
FA
FM
HA
HF
HM
IF
TF
RF
VA
VI
VM
10
Course to an Altitude
Course is flown making adjustment for wind
090
Unspecified
Position
0
CA Leg
AIXM Procedures Seminar 1-2 Sept 2010
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Course to Fix
A
Course is flown making adjustment for wind
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Direct to Fix
Unspecified position
Direct
DF Leg
AIXM Procedures Seminar 1-2 Sept 2010
A
13
Fix to Altitude
FA leg is flown making adjustment for wind
0
080
A
Unspecified
Position
8000'
AIXM Procedures Seminar 1-2 Sept 2010
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From a Fix to a Manual Termination
FM leg is flown making adjustment for wind
80
0
Radar
Vectors
A
AIXM Procedures Seminar 1-2 Sept 2010
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Racetrack
HA - Terminates at an altitude
HF - Terminates at the fix after
one orbit
A
340 0
HM - Manually terminated
AIXM Procedures Seminar 1-2 Sept 2010
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Initial Fix
IF
A
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Radius to Fix
RF Leg
C
A
B
Arc
Centre
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Track to a Fix
TF Leg
B
A
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Heading to an Altitude
Unspecified
Position
No correction made for wind
090 0
VA Leg
8000'
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Heading to Manual Termination
No correction made for wind
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Examples of FMS leg type capabilty
FMS
S/W version
MAINLINE: GE FMS
U5.0
U7.5
U10.7
Year
1990
Take-off update
yes
GPS
no
DME/DME
yes
Intertial
yes
IF
yes
TF
yes
CF
yes
DF
yes
FA
yes
FC
yes
FD
yes
FM
yes
CA
yes
CD
yes
CI
yes
CR
yes
RF
no
AF
no
VA
yes
VD
yes
VI
yes
VM
yes
VR
yes
PI
no
HA, HF, HM (holding) HM only
FRT
no
AIXM Procedures Seminar 1-2 Sept 2010
1997
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
no
no
yes
yes
yes
yes
yes
yes
HM, HF
no
2007
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
HM, HF
yes
REGIONAL: Universal FMS
SCN 15/16
SCN
SCN
SCN
101-320
405/505 601+/701+ 801+/901+
600/700
2001
yes
yes
yes
yes
no
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
no
yes
yes
yes
no
yes
yes
yes
no
yes
yes
yes
no
yes
yes
yes
no
yes
yes
yes
no
yes
yes
yes
no
yes
yes
yes
no
yes
yes
yes
no
no
no
yes
no
yes
yes
yes
no
yes
yes
yes
no
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
no
yes
yes
yes
no
yes
yes
yes
no
no
yes
yes
no
no
no
no
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Use Of Path Terminators
• Available Path Terminators are defined in PBN Manual
Nav Specifications
• If the RNAV system does not have leg type
demanded by procedure, the data packers have to
select one (or combination of) available leg types to
give best approximation
• Risk incorrect execution!
AIXM Procedures Seminar 1-2 Sept 2010
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Required Leg Types for RNAV 1 (P-RNAV)
1 automatically execute leg transitions and maintain tracks consistent with
the following ARINC 424 path terminators, or their equivalent.
• Initial Fix (IF)
• Course to Fix (CF)
• Direct to Fix (DF)
• Track to Fix (TF)
2 automatically execute leg transitions consistent with VA, VM and VI
ARINC 424 path terminators, or must be able to be manually flown on a
heading to intercept a course or to go direct to another fix after reaching
a procedure-specified altitude.
3 automatically execute leg transitions consistent with CA and FM ARINC
424 path terminators, or the permit the pilot to readily designate a
waypoint and select a desired course to or from a designated waypoint
AIXM Procedures Seminar 1-2 Sept 2010
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Advice
• Do not attempt to identify Arinc 424 codes for
conventional procedures
• Frequently RNAV systems cannot follow conventional
procedures without careful selection of one (or
combination of multiple) leg types
• Ensure that only leg types called up in RNAV/RNP spec
used
• Adequate training needed by procedure designers on
leg types
• Work with Data houses
AIXM Procedures Seminar 1-2 Sept 2010
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RNAV Procedure Description
• RNAV procedures defined by:
• Sequence of waypoints
• Identifier
• Co-ordinates
• Fly-over/fly-by/fixed radius
• Path Terminators - ARINC 424
• Altitude restrictions
• Speed restrictions
• Direction of turn
• Required navaid
AIXM Procedures Seminar 1-2 Sept 2010
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What Pilots Need to Know
• Waypoint names and sequence
• Fly-over/fly-by/fixed radius
• Turn direction
• Speed restrictions
• Altitude restrictions
• Required navaid
• Leg distance and magnetic track for error checks
• Fixes at certain waypoints for gross error checks
AIXM Procedures Seminar 1-2 Sept 2010
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Procedure Description for
Pilots
Speed/Altitude Restrictions
Leg distance & magnetic track
113
°
FAF
PT121
4000
°
Fly-over/fly-by/fixed radius
169° ARZ 29.3NM
236° ALM 27.4NM
203
Waypoint sequence
PT118
5000
PT119
4000
293
°
PT120
4500
Fix information
Turn direction
MAPt
RW20
AIXM Procedures Seminar 1-2 Sept 2010
350°
PT125
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Procedure Description for
Database Providers
• Textual description provide formal statement of procedure
• Often open to interpretation
• RNAV procedures require more specific details including
path terminators
• Can result in lengthy descriptions
• Alternative descriptive methods have been developed by
IFPP (OCP) and adopted by ICAO
• Tabular layout
• Formalised textual description
• Formalised short-hand description
AIXM Procedures Seminar 1-2 Sept 2010
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Tabular Description
RNAV Approach
Path
Terminator
Waypoint
Name
Fly
Over
Course/Track/
Heading ºM (ºT)
Turn
Direction
Altitude
Constraint
Speed
Constraint
Required
Navaid
IF
TF
CF
TF
FA
DF
SUSER
CV023
CV024
RW35L
RW35L
SUSER
Y
Y
348º (347.8º)
348º (347.8º)
-
L
-
+5000
4000
2680
370
770
5000
250
150
-
OKE
OKE
-
Bearing/
Range to
Navaid
LOM 262/29
-
VPA/
TCH
-3º/50
-
RNAV SID
Path
Terminator
Waypoint
Name
FA
DF
TF
RW20
FOKSI
PF213
Course/Track/
Fly Over
Heading ºM (ºT)
Y
201º (203.3º)
345º (346.8º)
AIXM Procedures Seminar 1-2 Sept 2010
Turn
Direction
Altitude
Constraint
Speed
Constraint
Required
Navaid
R
-
400
+5000
250
250
-
Bearing/
Vertical
Range to
Path Angle
Navaid
OKE 330/30
-
30
Formalised Description
Climb on track 047° M, at or above 800ft, turn right
[A800+; M047; R]-
FA
Direct to ARDAG at 3000ft
ARDAG[A3000]-
DF
To PF035 at or below 5000ft, turn left
-PF035[A5000-;L]-
TF (Fly-over)
To OTR on course 090°M at 210kts
-OTR[M090; K210]-
CF
From STO at or above FL100, turn
STO[F100+; L]-
TF (Fly-over)
left direct to WW039 at or above
WW039[F070+]-
DF
FL070, to WW038 at 5000ft
WW038[A5000]
TF
AIXM Procedures Seminar 1-2 Sept 2010
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Final Approach Segment (FAS) Data Block
For SBAS and GBAS procedures
• SBAS FAS in on board Data base
• GBAS FAS uplinked on GBAS Datalink
Ensures data not changed between validation and use
Consists of data + Integrity Field (CRC
AIXM Procedures Seminar 1-2 Sept 2010
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SBAS FAS DB contents
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•
•
•
•
•
•
•
•
•
•
Operation type
Service provider identifier
Airport identifier
Runway
Approach perf designator
Route indicator
Reference path data selector
Reference path ID (Aprch ID)
LTP/FTP latitude
LTP/FTP longitude
LTP/FTP ellipsoidal height
FPAP latitude
FPAP longitude
Threshold crossing height
TCH units selector (m/ft)
Glide path angle (GPA)
Course width at threshold
Length offset
Horizontal alert limit (HAL)
Vertical alert limit (VAL)
AIXM Procedures Seminar 1-2 Sept 2010
2 characters
2 characters
4 characters
5 characters
1 character
1 character
2 characters
4 characters
11 characters
12 characters
6 characters
11 characters
12 characters
7 characters
1 character
4 characters
5 characters
4 characters
3 characters
3 characters
Unsigned integer
Unsigned integer
Alphanumeric
Alphanumeric
Unsigned integer
Alpha
Unsigned integer
Alphanumeric
Alphanumeric
Alphanumeric
Signed Integer
Alphanumeric
Alphanumeric
Alphanumeric
Feet or meters
Unsigned integer
Unsigned integer
Unsigned integer
Numeric
Numeric
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Integrity Field
• Enables validation of integrity
• Use 32 bit CRC calculated using binary
representation
• The avionics, when using FAS data block, must
compare the resulting CRC remainder with the value
provided by the procedure designer.
• If the values do not match, the FAS data block will
not be used.
Produced by validated software
• One such available on ecacnav.com
AIXM Procedures Seminar 1-2 Sept 2010
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RNAV Procedure Data
• Tabular description
• Formalised Description
• FAS Data Block
All to be provided on verso side of chart
AIXM Procedures Seminar 1-2 Sept 2010
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Consistency with FMS/RNAV capabilty
• Not all rules are in PANS OPS
• What is allowed in PANS OPS (or at least not disallowed) may
not be possible to code
• Not all FMS/RNAV can use all allowed leg types
AIXM Procedures Seminar 1-2 Sept 2010
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Example
AIXM Procedures Seminar 1-2 Sept 2010
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Consistency with FMS/RNAV capabilty
• Not all rules are in PANS OPS
• What is allowed in PANS OPS (or at least not disallowed) may
not be possible to code
• Not all FMS/RNAV can use all allowed leg types
• Do not expect Procedure designers to know all nuances of
RNAV/FMS
• Encourage closer working with Data houses
AIXM Procedures Seminar 1-2 Sept 2010
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Questions?
AIXM Procedures Seminar 1-2 Sept 2010
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