Download - Coordinates

current number of VORs by 2020. With
WAAS in place, these older systems
can be discontinued, thereby saving
replacement costs while providing an
improved level of navigation service.
The most signi cant bene t of WAAS
can be realized in approach operations.
Before WAAS, the Instrument Landing
System (ILS) Category I approach was
the standard for precision approach
Legacy
NextGen
operations. With WAAS, future Category
I instrument requirements will generally
be satis ed through the use of WAAS
Localizer Performance with Vertical
guidance (LPV) approaches. LPV
approaches use the re ned accuracy of
WAAS lateral and vertical guidance to
provide an approach very similar to a
Category I ILS approach. Just like an ILS,
an LPV approach can provide minimums
as low as 200 feet at qualifying airports.
Unlike ILS approaches, WAAS LPV
approach procedures do not require the
installation or maintenance, both costly,
of navigation systems at the airport.
WAAS also enables another new type
of approach procedure called Localizer
Performance (LP). LP approaches are
non-precision approaches, providing
only lateral guidance, which is provided
by WAAS. LPs are being published in
locations where terrain or obstructions
do not allow publication of vertically
guided LPV procedures. LP procedures
can often provide lower minima than the
lateral navigation (LNAV) procedures
which rely on ground-based navigation
systems or on GPS alone. LPs will
be published at locations where the
terrain or obstructions do not allow
publication of LPV procedures.
In February of 2012, the FAA reached
a major milestone when the number of
published WAAS approach procedures
available nationwide exceeded 3,000.
By the summer of 2008, there were
already more than twice as many WAAS
approaches as Instrument Landing Systems
(ILS) approaches. The FAA’s goal is to
publish a LPV or LP approach procedure
for every instrument runway in the U.S.
Today, WAAS is providing the equivalent
of precision approach capability at more
than 1,400 airports throughout the United
States, including about 2,800 runway ends.
Who is using WAAS?
To date, over 70,000 WAAS-capable
receivers have been sold. This number
is increasing at a rate of approximately
1,000 units per month. Current WAAS
users can be found across many segments
of the aviation community. The general
aviation (GA) community was the rst
to support WAAS and continues to be
strong proponent today, aggressively
equipping with WAAS receivers that
include LPV certi cation. Regional
aircraft are also equipping with WAAS
LPV capability in increasing numbers.
There are over 2,100 regional aircraft
equipped so far. Horizon Airlines, which
equipped their Q-400s with WAAS,
Coordinates June 2012 | 23