Reno GPS Approach Question
- Thread starter Palmpilot
- Start date
Because life is cruel?
Palmpilot
Touchdown! Greaser!
I was hoping that approach designers had more objective reasons for setting minimums!
Trogdor
Pre-takeoff checklist
My guess would be the OCS is at a higher angle for the LNAV/VNAV than the LPV during design.
We would need a TERPS Elf to give a complete answer but I believe both approaches are designed differently - particularly because the LNAV/VNAV is primarily based on temperature while the LPV is based on glide path angle.
We would need a TERPS Elf to give a complete answer but I believe both approaches are designed differently - particularly because the LNAV/VNAV is primarily based on temperature while the LPV is based on glide path angle.
Clip4
Final Approach
dtuuri
Final Approach
"For the purposes of this article, we won't go into LPV approaches..."
RussR
En-Route
This situation is rare but does happen, and in general terms it all has to do with the location of the obstacle and the differing evaluation methods between LPV and LNAV/VNAV. The underlying surfaces are somewhat complex and are dramatically different between the two - one main reason as you suspect being the effect that temperature can have on Baro-VNAV systems, which are what the LNAV/VNAV criteria is designed for.
It is also possible that the accuracy of the "controlling obstacle" is having an effect. Briefly, for these evaluations, the worst-offending obstacle is identified for each type of procedure - meaning the one that causes the most increase in DA. But this initial evaluation is based on the surveyed obstacle height alone. Then after this "controlling obstacle" is determined, the accuracy of the survey data is looked at to see if it conforms to the requirement for that segment. If it does not, then the DA is further increased to account for this inaccuracy. So it is possible that the LPV obstacle causes less initial DA adjustment than the LNAV/VNAV obstacle, BUT has worse accuracy, and once this is applied, the LPV DA gets a further increase. This is a quirk of the criteria.
In this specific case, though, nobody can be 100% sure without seeing the source documents and actually doing the evaluation of the different surfaces.
unsafervguy
En-Route
cant say why, but i can tell what causes it, the nugget hotel.
luvflyin
Touchdown! Greaser!
C’mon now, there’s a story here. Give it up. That what happens in, stays in thing is for Vegas, not Reno