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Wide Area Augmentation System
Steve JacksonTERPs Standards Development Specialist
Flight Procedure Standards BranchAFS-420
Oklahoma City, OK
Final ApproachIntegrity Comparison
LNAV/VNAV (556 m by 50 m)LNAV/VNAV (556 m by 50 m)
LPV (40 m by 50 m)LPV (40 m by 50 m)
GLS (40 m by 12 m)GLS (40 m by 12 m)
A Comparison of Lateral Obstacle Clearance Criteria (LNAV/VNAV vs. LPV)
-15000
-10000
-5000
5000
10000
15000
-5000 15000 20000 25000 30000 35000
Distance from Runway Threshold (ft)
Dis
tan
ce
fro
m C
/L (
ft)
5000 100000
LNAV/VNAV OCS
LPV OCSLPV OCS
Existing GPS Procedures
• WAAS receivers can fly existing RNAV (GPS) procedures– Receiver may provide descent angle on existing LNAV
procedures
• Can fly the LNAV/VNAV minima line without approach certified Baro-VNAV– Temperature and altimeter restrictions don’t apply
Vertical Descent Angle vs. Glide Path
• Vertical Descent Angle was added as an aid in making a stabilized descent to the MDA on non-precision approaches (LNAV)
– ”the published angle is for information only – it is strictly advisory in nature” (AIM 5-4-5, h)
– Published angle is from FAF altitude to threshold at TCH, if published– May be published from a step down rather than FAF, if the step down would
penetrate the path from the FAF– Does not change any rules for non-precision approach, or MDA– Does not provide additional obstacle protection below the MDA over an
approach without the angle– Equipment is not required, can compute and use VVI
• Glide Path (LPV, LNAV/VNAV)– Obstacles assessed from the PFAF to the runway using sloped surfaces– Decision Altitude allows dip down– Flight inspected
WAAS Procedures
• Plan to develop WAAS LPV minima for all suitable IFR runway ends– Provide near precision approach with glide path– Developing ~300 LPVs per year
Charting with LPV minimum line
LPV Minimum Line
WAAS ChannelNumber
WAAS Approach ID
W=WAAS24=Runway 24
A=1st WAAS ApproachTo Rwy 24
Temperature Restriction
Does Not Apply to WAAS
Equipment
Airport Requirements
• Paved runway over 3200ft• No WAAS ground hardware required • Airport infrastructure needed for lowest minima
– Parallel taxiway– Medium intensity runway lights– Non-precision runway markings
• Survey
• WAAS avionics allow use of RNAV approaches as
filed alternates
– Alternate flight planning based on non-precision weather
requirements and the LNAV minima line
– Removing NA from GPS approaches unless required for
another reason
• Does not change the requirements for basic GPS at an
alternate
WAAS At Your Alternate
• WAAS UNAVAILABLE
• WAAS UNRELIABLE
• Inverse on the approach chart• Possible frequent short outages of the vertical
• Vertical NOTAMS not provided
• Flight plan based on LNAV only
• Can fly vertical guidance if it is available upon arrival
WAAS NOTAMS
Antenna Sensor(Beta)
NavigationComputer
Database
Controls
Position
Integrity
AlertsDeviations
DeviationsSteering
Displays
Autopilot
WAAS Class Gamma Configuration
Antenna Sensor(Beta)
NavigationComputer
Database
Controls
Position
Integrity
AlertsDeviations
DeviationsSteering
Displays
Autopilot
WAAS Class Beta Configuration
Antenna Sensor(Beta)
Position
Integrity
AlertsDeviations
DeviationsSteering
Displays
Autopilot
ControlsDatabase
NavigationComputer
WAAS Class Delta Configuration
WAAS Capabilities
• Why invest in WAAS?– Enhances en-route navigation performance and non-precision approach capability
over GPS alone– Allows WAAS equipped users to fly over 700 published LNAV/VNAV procedures to
minimums as low as 250 feet (typically higher based on terrain)– Allows WAAS equipped users to fly new LPV procedures which provide near precision
approach capability to runways where there is no ILS• These can be flown to minimums to as low as 250 feet
– Can be used at an alternate (flight plan based on LNAV only)– Advanced missed approach and departure procedures
• Better Than 99.99% Availability Of System• WAAS Specific Approaches (LPV) Published
– 72 published to date
• Comes with fault detection and exclusion (FDE)• Takes advantage of GPS Selective Availability being discontinued (higher
RAIM availability)
CRITERIA/POLICY LPV SURVEY PROCEDURE PRODUCTION
FLIGHT CHECK NFDC NACO INDUSTRY
8260.50 (9/6/02) 8260.19 (draft) [AFS-420/Tom Schneider] 8260.44 (DPs – later) 7110.65 (will initially be a notice)[ATP-104/Gary Powell] 8200.1 (RNAV Chg or order? will initially be a memorandum) [AVN-230/Dan Burdette] AIM – Aug 02 input/Feb 03 publication [AFS-420/Steve Jackson] NTAP [AFS-420/Steve Jackson] AFS-200 orders [AFS-200/Streeter] -800 ops specs -600 tests 7910.3 NOTAM [ATP-300/Gary Bobick] AC 150/5300-13 Appx 16 (surveys; infrastructure) [NFDC/Pat Fair] Airway Facilities Mx & Cert. (6700.XX?) [Mike Etchart] AC 90-94B? (WAAS) [AFS-410/Hank Cabler]
FAA Order 7350.6 [NFDC/Toni Tapscott] APS-1 [AND-720/Dave Peterson] Chart Legend [AFS-420/Steve Jackson] IACC [Valerie Watson] RAPT Order (8260.43A) [AFS-420] (work these concurrent ly)
Nat’l Reference System Ellipsoid vs. Geoid Need to know what survey standard is (Spec 405 (plus any interim guidance); AC 150/5300-13, Appx. 16) [AFS/AAS/ATA/ AVN are working issue]
8260.LPV (draft) 8260.19 Chg 3 (draft) 8260 Forms (-3, -5,-7, -9 & -10)Electronic forms (AVN-40/Barbara Cordell; AVN-100/Marv White?) Leg type Flyover/Flyby Turn direction Channel num ber (get from NFDC) Approach ID(RPI) (assigned by AVN-100) CRC wrapprocedure trans mission (FAS data) FAS data block [82.60.19 & 8260.10] (Alarm limits? HAL/ VAL data base vari ables in FAS?) [YES] ARINC-424 data provided to box manufacturers
Hand enter number checksum (Auto entry? Need software packing tool) Redo LNAV/VNAVs? (Ohio University study recommends develop ing a software screen ing model to deter mine which LNAV/ VNAVs have ade quate GEO coverage and can be ap proved w/o an initial flight inspection; Mitre Corp. has a software program and is cur rently evaluating existing LNAV/ VNAVs) Equip aircraft
NFDD (Paper/ Electronic) Transmittal letter (TL) Federal Register (8260 Forms) NASR
Transfer of data(Paper/Electronic) Charts Database 8260 Forms
IACC Specs Channel number Approach ID LPV minima line
Test of electronic data transfer
ARINC 424 CRC Receiver database MAJOR PLAYERS – LPV NFDCATA-110AVN-100
-200-500-40
AFS-400AIR-130DoDDatabase VendorsReceiver Manufacturers
Questions
You can find more details on our website at:
http://gps.faa.gov
Procedures information can be accessed at:
http://avn.faa.gov
Telephone: 703.528.8278 Fax: 703.528.05521520 N. Court House Road, Arlington, Virginia
1 block from Courthouse Metro (Orange Line)
Corner of N. Courthouse Rd. & Wilson Blvd.
Current GEO ServiceInmarsat III
• Main Problem Is Single Coverage Over the Majority of CONUS
INMARSAT 3AOR/W
54W
INMARSAT 3POR178E