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)

WAAS Scaling for LPV

Length shortenedfor illustration purposes

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

Relative Minima Achieved

LNAV

ILS

3o

LNAV/VNAV

LPV

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

LPV Candidate Airports(Runway ends 3200’ or greater)

• 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

Vertical Coverage Sample, Mar 28, 05

Additional WRS’s will improve vertical coverage

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.

Slides after this are backup

Current GEO ServiceInmarsat III

• Main Problem Is Single Coverage Over the Majority of CONUS

INMARSAT 3AOR/W

54W

INMARSAT 3POR178E

New U.S. GEOs

• Provides dual GEO coverage over CONUS and Alaska

Telesat107W

PanAmSat133W