GNSS Markets and Applications - Understanding GPS: Principles and Applications - page 646

5,000 public use airports in the United States. Other countries are implementing
such procedures, and there is almost universal acceptance of some sort of GPS
approach capability at most of the world's major airports.
In the execution of an NPA, the pilot or autopilot is given direction to enable the
aircraft to be maneuvered into the appropriate position for a descent toward the
runway. The descent is made with reference to an approach plate , which dictates
minimum safe altitudes for each phase of the approach. Altitude information is pro-
vided by a separate instrument—a barometric altimeter. DGPS is required to pro-
vide the performance required for vertically guided approaches. Traditional
category I, II, and III approaches involve guidance to the runway threshold in all
three dimensions. Local area differential corrections, broadcast from an air-
port-based GBAS reference station (see Section 8.6.1.3), are anticipated to meet all
requirements for even the most demanding (category III) approaches.
In 2003, the FAA declared WAAS operational for instrument flight operations.
WAAS broadcasts on the GPS L1 frequency, so signals are accessible to GPS receiv-
ers without the need for a dedicated DGPS corrections communications link. The
performance of this system is sufficient for NPA and new types of vertically guided
approaches that are only slightly less stringent than category I.
The GA market is seeing a surge of activity after publication of GPS NPA at the
busiest airports and most of the others. As described in Chapter 8, other SBASs are
being fielded or considered to provide services equivalent to WAAS in other regions
of the world. Also, as GALILEO is deployed, the use of GNSS by aviation for
en-route, approach and landing is expected to become even more widespread.
12.2.3 Land Navigation
By far, the most promising navigation market for GNSS in terms of sheer size is for
land navigation products. At the 2003 Civil GPS Service Interface Committee meet-
ing, it was reported by the DOT that there are more than 420 million cars and 130
million trucks in the world, with 150 million cars and 40 million trucks in North
America. (Americans drive or ride a total of 11 billion miles per day.) Initial use of
GPS technology for land navigation was for fleet tracking applications, but its use
for individual vehicle navigation is growing rapidly. In 2004, there were approxi-
mately 8 million GPS receivers in automobiles in the United States. At that same
meeting, it was forecast that safety improvements made via the application of GNSS
technologies will reduce the national annual traffic death rate to below 1 per 100
million miles driven, or about a 30% reduction from current levels.
The value of current fleet information provided by GNSS is evident for delivery,
emergency vehicle, and scheduled service fleet dispatch and control. AVLS are being
developed or installed in many of North America's 10.3 million trucking and emer-
gency fleets, currently involving about a million vehicles in North America.
Qualcomm Corp. is a pioneer of fleet tracking, with over 500,000 trucks and other
fleet vehicles tracked via its OmniTRACS System. Many of these are GPS equipped,
primarily outside of the United States and particularly in South America. Urban
transit buses are finding application of GPS for schedule maintenance and safety
enhancement. The drive toward increasing the capacity of the existing transporta-
tion infrastructure has spawned the emerging concept of intelligent transportation