More info on GNS 430/530 WAAS upgrade

wrote:

Another big "if" is whether WAAS and LPV will be around 5 years from now.

Now this speculation is something I never read before. What would be the
reason for the demise of this technology, assuming it does not survive the
next several years?

--
Peter
























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I can't see that happening, especially when RNP is being deployed
commercially. Boeing & Airbus are now certifying their newer airframes
for RNP .1, which allegedly integrates GPS, INS, and DME into the FMS.
The GPS portion requires RAIM and is much more reliable with WAAS.

TIS, on the other hand, is a whole other issue...

PPT33R wrote:

I can't see that happening, especially when RNP is being deployed
commercially. Boeing & Airbus are now certifying their newer airframes
for RNP .1, which allegedly integrates GPS, INS, and DME into the FMS.
The GPS portion requires RAIM and is much more reliable with WAAS.

TIS, on the other hand, is a whole other issue...

I am involved in the work being done with RNP. WAAS is not part of the
calculus at all in the FMS sensor hierarcy for RNP_SAAAR instrument
approach procedures. RNP 0.10 is acheived through complex interfaces of
FMS software with GPS as the primary sensor. WAAS is not used. The most
robust platforms (dual-thread aircraft, which will be a requirement where
RNP is needed for the missed approach, use blended, updated IRU position
along with GPS (or without GPS for a reasonable period of time in the
event GPS suddently fails).

WAAS's primary benefit is to provide the LPV glide-path for the LPV final
approach segment. The RNP_SAAAR criteria's final approach segment
glide-path is predicated on IFR-certified Baro VNAV.

As an aside, when the FAA commissioned WAAS, they "dumbed down" the Baro
VNAV criteria for public RNAV (GPS) IAPs, which increased existing VNAV
minimums. This was a blatent political move to make LPV minimums look
better.

The assessment concets for the VNAV obstacle clearance surfaces in the
RNP_SAAAR environment rightfully do an end-run around the dumbing down of
public VNAV obstacle clearance criteria.

"Peter R." wrote:

wrote:

Another big "if" is whether WAAS and LPV will be around 5 years from now.

Now this speculation is something I never read before. What would be the
reason for the demise of this technology, assuming it does not survive the
next several years?


The primary GPS system is operated by the military and has huge benefits for them. It
also has huge benefits to much of the population beyond the military and beyond
aviation. The incremential cost to operate the system for all civil users is zero.
The system is useful through the entire world.

WAAS, OTOH, is a United States system funded and operated by the FAA. It is only
useful in the United States and some nearby areas. It is a different implementation of
GPS augmentation protocol than proposed by a few other countries.

WAAS functions through transponders rented by the FAA on commercial satellites, plus
several expensive ground stations. The operating costs are in the hundreds of millions
of dollars a year. The system is being used by a very small part of general aviation.
Most air carrier and biz jets have no need for WAAS at all, plus it dies as soon as
they fly off shore.

The bean counters at the FAA have trouble keep justifying this huge annual expense for
very little benefit.

Tim wrote:

snip
The system is being used by a very small part of general aviation.

Are you saying that WAAS is only used by the aviation community? What
about those who use WAAS-enabled handheld GPS units for boating,
driving, and hiking/backpacking?

Oh, and don't forget the geo-cachers. ;-)


--
Peter

"Peter R." wrote:

Tim wrote:

snip
The system is being used by a very small part of general aviation.

Are you saying that WAAS is only used by the aviation community? What
about those who use WAAS-enabled handheld GPS units for boating,
driving, and hiking/backpacking?

Oh, and don't forget the geo-cachers. ;-)

--
Peter

That's what I am saying. All those other applications are ad hoc, and not
part of any government criteria for navigation. The improvements in
accuracy with WAAS in any Garmin hand-held I have used is not even worth
the processor overhead.

I had it in a Garmin 295 for several years and kept it turned off because
it dragged down the screen refresh rates significantly. I now have a 296,
where it does not have that issue, but it still increases processor
overhead for no real gain. I choose to leave it disabled and thus get a
nice, clean 3D solution.