Dick Smith:
Yep. That was I.
Since then the price appears to have gone from $50 to $150 m and Baro VNAV does almost the same job at hardly any cost..
A post on the previous thread said. “ airlines don’t need WAAS so will not willingly pay for it”
Sounds logical to me.
But I would like to see a proper cost benefit study that also
looks at the non aviation users.
What the airlines will willingly pay for isn't much use for judging the benefit that SBAS will bring to GA. All SBAS needs in any region is one or two geo-stationary satellites and a few ground reference stations. The benefit is then ILS like approaches that cost the airport the same as a bog standard LNAV. No need to install and maintain costly ILS infrastructure.
There are already over 4000 LPV approaches in the US. You can also fly the existing LNAV/VNAV approaches to the DA without baro-vnav equipment or cold temperature restricition. You have to be blind to not see that SBAS APVs are the way ahead.
the people at CASA appear to make out that LNAV+V does not improve safety over the existing RNAV
...and yet it took google all of 0.42 seconds to return the following from CASA:
"Australian NPAs are published with a constant angle approach path, which clears all minimum altitudes, and facilitates the use of a stabilised descent technique...
...the constant angle stabilised approach technique is the recommended flight technique for all aircraft.....
...Some non-APV (NPA) avionics have a VNAV function that displays the vertical path in an ILS-like fashion.....If this type of vertical advisory
information is used, the pilot is responsible to ensure that the minimum segment altitudes published on the approach chart are adhered to.
"
It has been standard in the airline world and recommended for GA to fly using the CDFA technique for some time now.
Note how the CASA CAAP makes no mention of the fact that in such a VNAV. approach that there is an actual GPS position in the data base that starts the continuous descent.
There isn't a position in the database to start the CDFA. The point at which the unit thinks you will start the descent depends on what altitude it thinks you are at, which isn't very accurate without SBAS.