GBAS Working Group Meeting - Sydney, 

Australia 

by Dieter Guenter GPS TAC/FAA ATO-W

In February, Airservices Australia (AsA) hosted the fourth Ground Based Augmentation 

System (GBAS) working group meeting in Sydney, Australia. 

The GBAS working group is an international working group originally established between FAA, EUROCONTROL, various air navigation service providers (Germany, Spain 

and Australia), European and American avionics industry, airline representatives, Boeing 

and Airbus. At this meeting in Sydney, representatives of many Asia Pacific Economic 

Conference (APEC) nations joined the working group for the first time. In addition to 

the core group participants, other nations participating were Japan, Korea, India, China, 

Chinese Taiwan, Brunei, Malaysia and Brazil. Industry/airline representatives were 

Honeywell, Thales, Lockheed Martin, Cathay Pacific, Qantas, Continental Airlines, FedEx, 

Boeing and Airbus. 

The working group meetings serve the purpose to discuss national and international GBAS 

acquisition plans; to identify areas of cooperation; and to discuss technical and operational topics like GBAS integrity analysis, ionospheric data collection, operational safety 

In this issue:

GBAS Working Group 

Meeting - Sydney, 

Australia...........................1 

LAAS Flight Testing is 

Heating Up!.....................2 

New WAAS GEO Service 

Leases Undergo Testing 

Prior to Integration into 

WAAS..............................3 

GBAS Approach Minima - 

“Knowing the Difference”................................4 

The SATNAV News SATNAV News SATNAV News SATNAV NewsSATNAV News is produced by the Navigation 

Services (ATO-W) branch of the Federal Aviation 

Administration (FAA). This newsletter provides 

information on the Wide Area Augmentation System 

(WAAS) and the Local Area Augmentation System 

(LAAS), and initiatives associated with the 

implementation of satellite navigation into the 

National Airspace System (NAS). 
2 

assessments, regulatory approval process, and early operational 

implementation activities. 

The Sydney meeting provided an excellent venue for technical interchange between all participants on their plans and 

activities. Many countries support the implementation of 

GBAS and presented their national plans and ongoing efforts. The presentations of Airservices Australia, DFS Germany, and AENA Spain outlined in detail the progress made 

since the last working group meeting. All three service providers have prototype GBAS systems installed and are involved 

in technical and operational evaluation activities. Other nations presenting their ongoing GBAS activities were Japan, 

China, Korea, and Brazil. 

AsA plans on being the first service provider to support regulatory approval for a LAAS at Sydney International Airport. 

A Honeywell “beta LAAS” has been installed at Sydney and 

AsA has successfully completed flight trials with Qantas 

Boeing 737 aircraft. A phased operational approval plan, a 

step-down program based upon operational experience, and 

Flight Operations Safety Assessment have been designed for 

Qantas Airlines, which has already taken delivery of nine 

GBAS-capable Boeing 737 aircraft. 

Boeing and Airbus again underlined the importance of early 

operational experience with GBAS CAT I on the path to 

GBAS CAT II/III and stated that all new generation Boeing 

and Airbus aircraft will include GLS (GNSS Landing System) options. Airline support is increasing with Qantas, Continental and FedEx starting to equip and requesting early operational approval for operations against existing GBAS prototypes. 

The GBAS working group moved from information exchange 

to coordination / harmonization of activities for successful 

implementation of GBAS technology. FAA technical knowhow and approval processes are sought after. Nations are 

developing their own processes but are still aiming to be in 

compliance with FAA practices. FAA and AsA signed a 

Memorandum of Cooperation to support mutual activities with 

focus on regulatory approval of GBAS. Common understanding and practice of system approval, and the use of common 

test cases and tools are the near term goals for the working 

group. 

LAAS Flight Testing is 

Heating Up! 

by Dave Peterson, FAA ATO-W; Kristi Foster, GPS

TAC/FAA ATO-W

As part of the research and development efforts to prepare 

for a non-Federal approval of the Local Area Augmentation 

System (LAAS) at Memphis International Airport, the FAA 

conducted a series of successful flight tests in early May. Using the LAAS Test Prototype, the flight tests were conducted 

at the FAA Technical Center in Atlantic City. The purpose 

of the flight tests was to determine the operational performance and feasibility of a LAAS complex approach. The 

aircraft used for the tests was the Tech Center’s Boeing 727. 

The approach was developed to mirror one of the existing 

RNAV GPS approaches at Memphis Airport using the 

waypoints and transitioning from the arrival corner posts to 

the final approach segment. The only difference between the 

Atlantic City and Memphis procedure is that the actual headings align the aircraft with the Atlantic City runway instead 

of the Memphis runway. 

Four expert Tech Center test pilots (Mark Ehrhart, Keith 

Biehl, Larry VanHoy, and Lorry Faber) flew the procedure to 

determine any possible limitations of the approaches. Despite the variance in the pilots’ technique, they agreed that 

the LAAS procedure was very flyable and provided them with 

some understanding of what to anticipate during the approach. A total of 30 approaches were flown and although the 

test report is still in development, the initial reports and preliminary analyses indicate that it is a very useful and beneficial procedure. 

As anticipated, the command guidance was very accurate 

and allowed the pilots to navigate the aircraft through turns 

flying the paths right on track. Even with severe crosswinds, 

the procedure was very manageable which allowed the pilot 

more than enough time to prepare the aircraft for landing. 
3 

The pilots performed various turns to see if a different radius 

would impact the performance, and it did not. The pilots also 

varied the speeds for the approach to determine any impacts 

and still found the approach to be very easy to track and very 

stable. During the different approaches, the pilots found the 

cockpit workload to be very low. 

Perhaps one of the greatest benefits noticed during the approach was how the pilots could pull the throttles back to an 

idle descent and track the glide path as the aircraft crossed 

the corner post waypoint 35 miles from the airport at 10,500 

feet. This was done with lateral and vertical guidance from 

start to finish. During this descent there was a noticeable 

reduction in noise and the throttles were only applied after 

the final turn onto the final approach segment. This was 

significantly different from current approaches that use multiple radar vectors and speed adjustments to arrive at the 

final approach segment. 

The flight tests also illustrated significant fuel savings. The 

preliminary calculations show reduced fuel burn between the 

normal step-down approaches and the continuous descent 

approach (which still met all the terminal area minimum altitudes). Initial recordings show that there was a savings of 

500 to 700 pounds of fuel used per approach, an increasingly 

important factor as fuel costs continue to escalate. 

The flight tests at the Tech Center were a precursor to flight 

tests planned at Memphis in September 2006. These flight 

tests will be performed by Federal Express pilots using a Federal Express Boeing 727. The FAA (Southern Region, Memphis ATC, and Headquarters), in conjunction with 

Honeywell, Federal Express, Boeing, and Rockwell Collins 

have developed an operational flight test concept. The activities at Memphis will test these potential applications and 

determine the feasibility and benefits of using LAAS in the 

terminal area. The LAAS Program Office is closely overseeing this project and is using the results to make necessary 

changes to the system and operational utilization. The RNP 

Program Office is also reviewing these applications to determine what the future potential might be. These exciting flight 

tests are helping to build a foundation for the continued development of the LAAS capability. LAAS, in combination 

with other systems, such as ADS-B and automation for the 

TRACON and tower, has the potential for increasing efficiency in the terminal area and producing dramatic economical savings for users. 

New WAAS GEO Service 

Leases Undergo Testing 

Prior to Integration into 

WAAS 

by Grace Pazos, GPS TAC/FAA ATO-W; Ed Sigler,

GPS TAC/FAA ATO-W

Testing and integration is underway for two new satellite navigation transponders being leased by the FAA that will soon 

become an operational part of WAAS. The two navigation 

transponders, hosted on PanAmSat and Telesat geostationary (GEO) satellites, are components of the Geostationary 

Communication and Control Segment (GCCS) within the 

Wide Area Augmentation System (WAAS). The purpose of 

the GCCS is to generate and transmit the WAAS signal in 

space (SIS). The WAAS SIS provides WAAS-enabled GPS 

receivers with information that enables increased position 

accuracy. The information provided via the SIS also allows 

WAAS-enabled receivers to have very high confidence (integrity) in the computed position. Finally, the SIS can be used 

as a ranging source, similar to the signals of GPS satellites. 

GCCS System 1 consists of the WAAS navigation payload 

hosted on the PanAmSat geostationary satellite (Galaxy XV 

at 133 degrees West) and two GUSTs (GEO Uplink Subsystem Type-1) - one in Napa, California and the other in 

Littleton, Colorado. GCCS System 2 consists of the WAAS 

navigation payload hosted on the Telesat geostationary satellite (Anik F1R at 107.3 degrees West) and two GUSTs - one 

in Brewster, Washington and the other in Woodbine, Maryland. PanAmSat Galaxy XV is assigned pseudo random number (PRN) #135 and Telesat Anik F1R is assigned PRN #138. 

GCCS System 1 data link only (DLO) testing started April 

12, 2006 and completed April 26, 2006. (DLO service means 

that the GCCS System 1, when introduced into WAAS operational service, will not provide a ranging capability similar 

to GPS satellites. The DLO approach was adopted in an attempt to minimize WAAS service disruptions caused by the 

relocation of the Inmarsat 3 satellite from the Atlantic Ocean 

to the Pacific Ocean.) Tests were conducted at Raytheon 

Corporation in California with support staff at both the Napa 

and Littleton GUST sites. The preliminary acceptance tests 
4 

were completed successfully. Additional activities to integrate the GCCS System 1 service with WAAS will continue 

through this summer with operational WAAS broadcasts expected to begin in October. The ranging function will be 

added to GCCS System 1 in the spring of 2007 after additional testing and certification. 

The current outlook for the completion of GCCS System 2 

(Telesat) preliminary acceptance testing is late 2006. GCCS 

System 2 integration into the WAAS, with full capability, is 

currently expected to be complete in the spring of 2007. 

During the testing period, non-aviation WAAS-enabled GPS 

receivers will be able to use the signals from the new GEOs. 

During this period, the signals from the new GEOs will indicate that the signals are under test, preventing aviation-certified receivers from using the signals. Once the systems are 

certified and integrated into WAAS, the test indication will 

be removed, allowing use by aviation-certified receivers. 

Lockheed Martin Transportation and Security Solutions 

(LMTSS) is the prime contractor for the GCCS, supported 

by key subcontractors, Raytheon Company and Dunhill. The 

Raytheon Company is the prime contractor for the WAAS. 

GPS Approach Minima - 

“Knowing the Different 

Minima” 

by Marty Heller, GPS TAC/FAA ATO-W

Global Positioning System (GPS) and subsequent system improvements have revolutionized the manner in which we fly. 

The Wide Area Augmentation System (WAAS) and new avionics have lowered instrument approach minimums and increased the types of GPS and RNAV* (GPS) lines of minima. 

This article attempts to clarify the nomenclature of these different types of GPS approach minima. 

RNAV lines of minima now include: LNAV, LNAV/VNAV, 

LPV and circling. Not all GPS avionics can fly all GPS 

minima lines. (Of course, if the equipment isn’t Instrument 

Flight Rules (IFR) certified and installed, one can’t legally fly 

any GPS approach.) For starters, the originally GPS capability only provides two-dimensional, lateral navigation (LNAV). 

Vertical navigation (VNAV) became possible with the advent of flight management systems (FMS) with barometric 

pressure inputs. These systems are referred to as Baro-VNAV 

FMS. The latest advance is WAAS. WAAS provides localizer performance with vertical (LPV) guidance. 

Approach Charts

Operational since 2003, some individuals might be wondering 

why they still haven’t seen a WAAS approach chart. This is 

because WAAS is a system which enables LPV minima. Almost 

400 LPV procedures have been published already, with a goal 

of producing 300 more each year. So you won’t see a ‘WAAS’ 

approach chart — what you will see is a RNAV(GPS) approach chart. (For an example, see Figure 1). 

Figure 1. San Angelo Regional/Mathis 

* RNAV is “Area Navigation” Field (SJT) RNAV (GPS) Rwy 21 

NOT FOR NA T FOR NAT FOR NA T FOR NAVIGATION
5 

Which Minima can your Equipment fly?

Every IFR-certified and installed GPS unit allows the pilot to 

descend to Lateral Navigation LNAV, or straight-in, minima. 

Baro-VNAV-equipped GPS systems can descend to LNAV 

and LNAV/VNAV minima. Certified WAAS receivers can 

descend to LNAV, LNAV/VNAV, and LPV minima. 

Hard to remember? Another hint for knowing the different 

GPS minima is the Decision Altitude (DA) designation. Only 

procedures with vertical guidance have DAs, as demonstrated 

in figures 1 and 2. The Minimum Descent Altitude (MDA) 

abbreviation on the minima line indicates that only LNAV is 

provided. While a descent angle might be provided for an 

LNAV approach, the angle is only to aid in a stabilized descent, not provide vertical navigation; and the MDA must 

still be respected. The final authority for knowing what your 

aircraft can fly is your pilot’s operating handbook (POH) and 

any associated supplemental pilot/flight manuals. The POH 

clearly spells out whether your aircraft is authorized to fly in 

IMC and what approaches it is authorized to fly. 

Other Minima Lines

The GNSS Landing System (GLS) decision altitude (DA) 

was originally added to some charts as a place holder for ongoing upgrades to WAAS and for the Local Area Augmentation System (LAAS). GLS is now being replaced by LPV on 

the RNAV(GPS) charts. The acronym, ‘GLS’ is now associated with the LAAS minima and will be published on a separate chart when LAAS approaches become available. 

LAAS

LAAS will augment the GPS and complement WAAS by providing an all-weather approach, landing, and surface navigation capability. Curved approach paths, not possible using 

the current instrument landing systems, will be possible for 

Category I, II, and III precision approaches as the system 

evolves. Approaches will be designed to avoid obstacles, restricted airspace, noise sensitive areas, or congested airspace. 

Federal Aviation Administration 

800 Independence Avenue, SW 

Washington, DC 20591 

http://gps.faa.gov 

Increased accuracy through LAAS will also allow more arrival and departure procedures. 

Need More Information?

You can find a condensed version of the information in this 

article on page A1 of each U.S. Terminal Procedures Flight 

Information Publications and in the Aeronautical Information Manual (AIM) paragraph 5-4-5, j. More GPS and WAAS 

information is also available in the AIM paragraphs 1-1-19 

and 1-1-20. The following websites also have information on 

GPS approaches: 

X FAA Satellite Navigation web site: http://gps.faa.gov 

X Aeronautical Information Manual: http://www.faa.gov/ 

atpubs/AIM/AIM.pdf 

X Instrument Procedures Handbook; Chapter 5 : 

http://www.faa.gov/library/manuals/aviation/ 

instrument_procedures_handbook 

X FAA National Aeronautical Charting Office (NACO) In 

troduction to IFR Symbols: 

http://www.naco.faa.gov/content/naco/online/pdf_files/ 

7th_IAP_Intro.pdf 

Related advisory circulars are accessible at: http://faa.gov/ 

regulations_policies. They include: 

X AC 90-94, Guidelines for using Global Positioning System 

Equipment for IFR En Route and Terminal Operations 

and for Nonprecision Instrument Approaches in the U.S. 

National Airspace System 

X AC 90-97, Use of Barometric Vertical Navigation (VNAV) 

for Instrument Approach Operations Using Decision 

Altitude 

X AC 90-100, U.S. Terminal and En Route Area Navigation 

(RNAV) Operations 

Figure 2. Approach Minimum Equipment Comparison 

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