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#1
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LPV vs LNAV/VNAV?
Can someone explain to me the difference between these two approach
types, and how they relate to WAAS? A sample approach that has both is KARR RNAV(GPS) RWY 9. LPV DA is 956, LNAV/VNAV DA is 990. |
#2
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LPV vs LNAV/VNAV?
paul kgyy wrote:
Can someone explain to me the difference between these two approach types, and how they relate to WAAS? A sample approach that has both is KARR RNAV(GPS) RWY 9. LPV DA is 956, LNAV/VNAV DA is 990. LPV requires a TSO 146 navigator. VNAV requires Baro VNAV (only found in high end aircraft) or, now, a TSO 146 navigator. With a TSO 146 navigator the VNAV glide-path is not as carefully calculated as the LPV glide-path. It's as safe, but not as good for minimums, etc. |
#3
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LPV vs LNAV/VNAV?
Both of these options require a WAAS receiver, I presume? |
#4
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LPV vs LNAV/VNAV?
paul kgyy wrote:
Both of these options require a WAAS receiver, I presume? Yes, and if WAAS is not available to the standards required by the specs then the 146 box will not accept the WAAS solution, which means (using Garmin as an example) LPV, L/VNAV, and LNAV+V will not be available; only LNAV will be available. |
#5
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LPV vs LNAV/VNAV?
"Sam Spade" wrote in message ...
paul kgyy wrote: Both of these options require a WAAS receiver, I presume? Yes, and if WAAS is not available to the standards required by the specs then the 146 box will not accept the WAAS solution, which means (using Garmin as an example) LPV, L/VNAV, and LNAV+V will not be available; only LNAV will be available. And I can attest to that, Sam, because I've experienced having an LNAV/VNAV approach "Downgraded to LNAV" only. I couldn't take the time just then to check the SV reception page, to see if the problem might have been explained there. |
#6
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LPV vs LNAV/VNAV?
Sam Spade wrote:
paul kgyy wrote: Both of these options require a WAAS receiver, I presume? Yes, and if WAAS is not available to the standards required by the specs then the 146 box will not accept the WAAS solution, which means (using Garmin as an example) LPV, L/VNAV, and LNAV+V will not be available; only LNAV will be available. I don't think so. A TSO C129a GPS driving a FMS with baro VNAV should be able to fly RNAV(GPS) approaches using LNAV/VNAV minimums. No WAAS involved. Mike |
#7
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LPV vs LNAV/VNAV?
Sam Spade wrote: paul kgyy wrote: Both of these options require a WAAS receiver, I presume? Yes, and if WAAS is not available to the standards required by the specs then the 146 box will not accept the WAAS solution, which means (using Garmin as an example) LPV, L/VNAV, and LNAV+V will not be available; only LNAV will be available. Something I never understood is why LNAV approaches don't automatically show a glideslope so that the airplane arrives at the MDA at the VDP. |
#8
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LPV vs LNAV/VNAV?
Andrew Sarangan writes:
Something I never understood is why LNAV approaches don't automatically show a glideslope so that the airplane arrives at the MDA at the VDP. Because L stands for lateral? -- Transpose mxsmanic and gmail to reach me by e-mail. |
#9
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LPV vs LNAV/VNAV?
Andrew Sarangan wrote:
Something I never understood is why LNAV approaches don't automatically show a glideslope so that the airplane arrives at the MDA at the VDP. Perhaps because it wasn't part of the certification at the time? -- Peter |
#10
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LPV vs LNAV/VNAV?
Peter R. wrote: Andrew Sarangan wrote: Something I never understood is why LNAV approaches don't automatically show a glideslope so that the airplane arrives at the MDA at the VDP. Perhaps because it wasn't part of the certification at the time? Perhaps my comment was not clearly stated. When you fly an LNAV approach (or any nonprecision approach for that matter) instead of the traditional dive and drive you can mentally calculate the vertical speed required (VSR) to arrive at the VDP at a constant glide angle . That mental calculation could be easily performed by the GPS and displayed as a glideslope. But I have not seen any GPS do that. Certification is irrelevant. We are not talking about a lower minimum or anything new that we not already allowed to do. |
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