WAAS Service Expands In Alaska

Since commissioning in July 2003, WAAS has been providing valuable benefits to aviation users. Pilots use WAAS for improved situational awareness and also to fly new 

WAAS-enabled localizer performance with vertical guidance (LPV) approach procedures. 

However, until very recently, WAAS service was very limited in Alaska. WAAS was available only in the southeastern portion of Alaska and, even there, only with limited availability. At the beginning of August, this changed and WAAS was expanded throughout Alaska. 

This expansion of service was made possible by the installation and integration of four 

new WAAS wide-area reference stations (WRS) into the WAAS network. On August 4th, 

these four new stations - located in Barrow, Bethel, Fairbanks, and Kotzebue - came on 

line. Each new station brought with it contributions to the total gain in WAAS coverage. 

This accomplishment was the result of several years of work to identify and approve the 

most beneficial WRS locations, complete site surveys, install equipment, code and test 

corresponding software upgrades, and conduct test and integration activities. With these 

activities now complete, the expanded service is operational. 

The differences in WAAS service coverage are significant. In Southeast Alaska, WAAS 

availability was at 75% or less for those aviation operations requiring vertical guidance. 

Now, WAAS models predict service to be available, on average, 98% of the time. Even 

more significant is the extension of WAAS service to the remainder of Alaska. In the 

In this issue:

WAAS Service Expands in 

Alaska..................................1 

New WAAS Ready to Go.....3 

WAAS Avionics Update.......3 

LPV Watch...........................4 

Integrity Design Documents 

Completed for LAAS..............4 

The SATNAV 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). 

WAAS Coverage Availability Plots Produced by MITRE Corp. These simulations of WAAS service

availability are based on a set of pre-determined assumptions. Actual performance may vary.

(All Rights Reserved)

Availability Model of WAAS Service Supporting

LPV Approach Capability Prior to the Integration

of Additional Alaska Stations

Federal Aviation Administration 

800 Independence Avenue, SW 

Washington, DC 20591 

http://gps.faa.gov

Availability Model of WAAS Service Supporting

LPV Approach Capability After the Integration of

Additional Alaska Stations
2

past, WAAS had been extremely limited in its ability to support aviation applications. Now, WAAS service is available 

throughout most of the state 95% of the time or better. 

This expanded service is particularly beneficial in Alaska 

where air transportation is often the only practical mode of 

transportation to and from many remote parts of the state. 

Mountains and vast stretches of remote terrain make it impractical to install and maintain sufficient ground-based navigation equipment to effectively serve the entire state. Satellite navigation systems, such as the Global Positioning System (GPS) and WAAS, offer the ability to serve areas of 

Alaska where traditional navigation systems are simply not 

available. Initially, GPS was adopted to overcome the challenges posed by the terrain and vastness of Alaska, but GPS 

alone still has its limitations. WAAS provides higher availability for all aviation operations than provided by GPS alone. 

WAAS also improves the accuracy, including the reliable vertical guidance, required to fly LPV approaches. Three airports in Alaska are currently awaiting flight check for LPV 

procedures (Anchorage International Airport - PANC, 

Emmonak Airport – PAEM, and Homer Airport – PAHO). 

The extension of WAAS service into Alaska is the first step in 

broadening WAAS coverage. In years to come, WAAS service will also be expanded to Canada and Mexico. Installations of WAAS stations in both Canada and Mexico have recently been completed and are scheduled to begin coming 

on-line starting in September 2007. 

- Mary Ann Davis, FAA GPS TAC

WAAS Wide-Area Reference Stations (WRS) Locations - The new Alaskan WRSs complement the original twenty-five WRSs

that have been in operation since WAAS commissioning in 2003. Nine more WRSs, located in Canada and Mexico, will be

incorporated into the WAAS in the years to come.
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New WAAS GEO Ready To Go

In November, the FAA’s Wide Area Augmentation System 

(WAAS) achieved a new milestone – the addition of a new a 

WAAS navigation transponder onboard a geostationary satellite (GEO). This new GEO service is the first of two GEOs 

to be integrated into WAAS service as part of the Ground 

Communications and Control Segment (GCCS) contract with 

Lockheed Martin. 

The new GEO, PanAmSat (PAS) Galaxy XV, is located above 

the equator over the Pacific Ocean at 133° W longitude. From 

this orbital position, the PAS GEO is able to broadcast the 

WAAS signal across the entire U.S. As such, this new GEO 

service restores WAAS aviation service to New England. 

Portions of New England were adversely affected earlier this 

year when the Inmarsat AOR-W GEO, the satellite which 

hosts one of the current operational WAAS navigation transponders, moved west from its position above the Atlantic 

Ocean to a new position above the Pacific Ocean. 

The PAS GEO, launched in October 2005, has been undergoing a series of tests and integration with WAAS ground 

components. Operational requirements and tight safety tolerances dictate an extended integration and test phase for 

the new GEO services. One aspect of the WAAS signal is 

that it is ‘GPS-like’, meaning it can be used as a ranging 

source similar to GPS satellite signals. However, testing and 

satisfying the strict ranging requirements involve GEO system tuning and testing conducted over weeks of time. In 

order to bring the PAS GEO into the WAAS as soon as possible, in part to return WAAS aviation service to New England sooner, the decision was made to initially forego ranging service verification on the PAS GEO. What does this 

mean to the users? It means that users in the Northeastern 

U.S. have a return of WAAS aviation service. It also means 

that users across the U.S. have an increase in WAAS aviation service availability. 

With the PAS GEO service operational within the WAAS, the 

FAA now turns its focus to the testing and introduction of ranging service for the PAS GEO (to be available in late spring 

2007) and the introduction of service on the second GCCS 

GEO, Telesat (also to be introduced in late spring 2007). 

 - Ed Sigler, FAA GPS TAC

WAAS Avionics Update

The race to provide WAAS avionics to the aviation community is proving to be more of a marathon than a sprint. More 

than three years since the WAAS system was 

commissioned as a primary means of navigation, few options are on the shelf today, but 

manufacturers are working to change that. 

Leading the pack in the general aviation (GA) 

market is Garmin International Inc., with the 

GNS 480 which had been the only certified 

receiver that could be used to fly a localizer 

performance with vertical guidance (LPV) approach. In the homestretch, Garmin continued 

in its efforts and recently announced the long 

awaited WAAS LPV upgrade to the GNS 430 

and GNS 530 series of panel mount receivers. Garmin recently crossed the finish line 

with its G1000 by receiving approval for its integrated avionics system, with WAAS LPV capability, as part of the original 

equipment of the newly certified Cessna Mustang. 

Garmin’s competition is limited. Chelton Flight Systems, who 

has partnered with FreeFlight Systems to produce an Electronic Flight Instrument System (EFIS) with a GPS/WAAS 

sensor certified for enroute operations will provide LPV certification for the EFIS when a compatible GPS/WAAS receiver 

is available to them. Honeywell has hinted that they also 

plan to introduce WAAS to its Bendix/King line of avionics. 

With sales of more than 4,000 GNS 480 WAAS receivers, 

and more than 17,000 receivers signed up for the GNS 430 

and GNS 530 upgrade, Garmin has set the pace for WAAS 

avionics in the GA market. 

In the past, avionics manufacturers have been cautious about 

investing in WAAS for the business and regional aviation 

market due to high development costs, a smaller market, 

and a customer base that uses airports where Instrument 

WAAS GEO Footprints – POR, AOR-W, PanAmSat

(November 2006) and Telesat (Spring 2007)
4

Landing Systems (ILS) are the rule rather than the exception. However, as the market begins to realize the benefits of 

WAAS relating to LPV approaches, Required Navigation Performance (RNP), and flight planning, all realized as the FAA 

continues its transition toward the use of satellite navigation; 

avionics manufacturers are taking notice and development 

efforts are under way. 

Universal Avionics is well off the starting block with their WAAS 

avionics developmental efforts. They report impressive results flying with a WAAS equipped ‘red-labeled’ UNS-1 in their 

corporate aircraft, and enjoy its seamless international Global Navigation Satellite System (GNSS) capabilities. Its market entry includes a dual flight management system (FMS) 

solution expected to be certified by the second quarter of 

2007. 

Rockwell Collins and CMC are currently developing FMS integrated WAAS avionics under a contract with the FAA to 

equip their fleet and promote general adoption in the market. 

Rockwell Collins will equip Learjet and Challenger 604 flight 

inspection aircraft with its WAAS GNLU-955 multimode receivers. Completion of this effort is expected February 2007. 

Rockwell Collins is also under contract with the FAA to develop a Technical Service Order (TSO) certified GPS-4000S 

receiver for WAAS-enabled enroute, terminal, and LPV approach operations, as well as a supplemental type certificate 

(STC) for Bombardier CRJ aircraft. Lastly, the FAA Technical Center (FAATC) has a contract with CMC Electronics to 

integrate a WAAS-enabled sensor into the Honeywell Primus2000 FMS unit in the FAATC Global-5000 aircraft. In addition to equipping FAA aircraft, these efforts are expected to 

springboard development and certification of related FMS 

systems and airframes. 

While the industry initially took a wait-and-see approach to 

development, the improving WAAS coverage, LPV procedure 

production, and resulting customer demand—ranging from 

GA to the airlines—has forced avionics manufacturers to 

tighten their laces and join the race. 

- Tom Salat and Brad Zeigler, FAA GPS TAC

(This article covers a sample of work currently underway in the WAAS

avionics market. If you or your company is involved in any related initiatives not included here, please e-mail Tom Salat (thomas.ctr.salat@faa.gov)

and we will incorporate this information in future updates on avionics activities. Please include “WAAS Avionics Initiative” in the subject line of the

e-mail.)

LPV Watch

Every 56 days, new procedures are published as a part of 

the Terminal Procedures Publication (TPP) cycle. On occasion, procedures may be published during the interim months 

as a part of an Operations Change Notice (OCN). As of the 

last TPP (November 23, 2006), there were 640 published 

localizer performance with vertical (LPV) approaches. The 

table above shows the types of airports and runways currently served. There are now 377 airports that have LPVs 

and that number is growing every 56 days. A listing of current airports served by LPVs (including information on runways served, corresponding decision altitudes, WAAS channel numbers, and other information) can be found on our 

website. To access this information, go to http://gps.faa.gov

and select the GPS/WAAS Approaches button from the front 

page. 

Integrity Design Documents

Completed for LAAS

The Local Area Augmentation System (LAAS) program has 

achieved another milestone bringing the implementation of 

satellite navigation for Category (CAT) I operations closer to 

reality. The LAAS uses ground stations and a local area 

broadcast to augment the accuracy of the Global Positioning 

System (GPS) for use by commercial aviation in terminal 

operations. In September 2004, the FAA Administrator directed the descoping of a Honeywell production contract for 

60 CAT I LAAS ground stations to focus the program’s resources on research solutions to key integrity risk areas. This 

research has now culminated in the validation of the algorithm design of 11 integrity monitors that are necessary to 

perform CAT I landings. 
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The requirement for a ground-based 

augmentation system, or GBAS (the 

international term used for LAAS), to 

perform instrument approaches 

down to 200 feet is very demanding. 

The requirement states that a ground 

station shall not transmit hazardous 

misleading information to the aircraft 

GPS-derived position no more than 

one in 10 million landings. To meet 

this requirement, the LAAS ground 

station employs 11 monitors that 

check the information used to correct 

ranging information from the GPS 

satellites. These monitors check atmospheric delays associated with the troposphere and ionosphere, biases associated with ground station antennas and 

receivers, daily and seasonal environmental changes, and 

satellite malfunctions. 

Each monitor requires a software design document called an 

Algorithm Description Document (ADD) that consists of four 

main sections. The first section of each document describes 

the threat that the monitor is trying to mitigate. The second 

section describes all the top level and derived requirements 

that the monitor must meet. The third section details algorithm equations that need to be coded and the forth section 

contains the analysis that validates the algorithm equations. 

All the ADDs have now been completed and have been presented to a LAAS Integrity Panel for approval. Once approved, Honeywell will code the algorithms and install them 

in a Honeywell-developed LAAS prototype at Memphis International Airport. Using this prototype, flight tests will be conducted along with stability testing to verify that the algorithms 

work in an operational environment. Testing will be difficult 

because some of the conditions that the monitors are to detect are rare events. For example, storms in the ionosphere 

that can cause errors may occur only once every 4 years. 

The next phase of the program is to support full implementation of the monitors in a certifiable system being developed 

by Honeywell through a contract with Airservices Australia 

(ASA). In February 2006, FAA and ASA signed a memorandum of cooperation (MOC) to support approval of a Standards and Recommended Practices (SARPs)-compliant 

GBAS, based on the FAA-approved Honeywell design. 

Before this equipment can be used 

operationally, it must go through two 

certification processes. The first process is to approve, or certify, the design of the system for aviation use. 

The second approval is the equipment installation for each particular 

location where it will be used, also 

known as facility approval. As a part 

of the FAA/ASA MOC, the FAA will 

support the system approval. ASA 

will then approve the installation of 

the equipment, or facility certification, 

for operation of this equipment in the 

airspace at Sydney. 

FedEx also plans to upgrade the Honeywell LAAS installed 

at Memphis. Memphis is a major hub for FedEx and the 

increased accuracy of LAAS out to 60 miles can reduce operation delays in inclement weather. In order for the algorithms to work on the Memphis equipment, the current processors and antennas will need to be upgraded and certified 

to DO-254 hardware standards. These modifications will bring 

the Memphis equipment up to the same design that will be 

approved in Australia as a part of the FAA/ASA MOC. As a 

result, after the system at Memphis receives the required 

upgrades, it will only need to go through the facility certification process. The FAA will approve the facility at Memphis. 

If everything goes according to plan, the Memphis LAAS can 

be operational for CAT I service late in 2008. 

In summary, the integrity risks and design problems associated with using LAAS for all-weather CAT I instrument approaches down to 200 feet have been resolved. The mitigation of these risks and the design of the algorithms to support 

this service have been documented in 11 algorithm description documents. The next step is to certify these algorithms 

to DO-178 software standards and to certify the hardware 

they interface with to DO-254 standards. This certification 

program is being completed cooperatively between the FAA 

and ASA. Plans include an operational system at Sydney 

International Airport with one to follow shortly thereafter at 

Memphis International Airport. After experience is gained 

with these systems in CAT I service, a determination will be 

made as to what improvements are necessary to support CAT 

II/III service. CAT II/III service supports landings in all weather 

conditions including times when visibility reaches zero. 

- Rich Lay FAA GPS TAC

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