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#1
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![]() Both of these options require a WAAS receiver, I presume? |
#2
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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. |
#3
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"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. |
#4
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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 |
#5
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Mike Adams wrote:
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 That has been true for a long time. The context of the recent discussions in this forum have been about TSO C-146 (RTCA DO-229C). |
#6
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![]() 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. |
#7
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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. |
#8
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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 |
#9
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![]() 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. |
#10
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Andrew Sarangan wrote:
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. Certification is most certainly relevant to your query, as that is most likely what kept that feature out of the TSO C129a certified IFR GPS's. A handheld Garmin 196 (I think that is the model a pilot-friend had with him a couple of years ago) that we took up on a practice IFR flight did just that. It displayed a glideslope for a non-precision approach. If the cheaper handhelds can do it, then why don't their IFR-certified TSO C129a big brothers do it? Because it wasn't part of the certification and therefore, regardless of their ability to provide this feature, are restricted from doing so due to the certification. -- Peter |
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Thread | Thread Starter | Forum | Replies | Last Post |
LNAV, VNAV and LPV | Andrew Sarangan | Instrument Flight Rules | 5 | January 14th 07 01:57 PM |
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