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LPV vs LNAV/VNAV?



 
 
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  #1  
Old January 5th 07, 04:59 PM posted to rec.aviation.ifr
Paul kgyy
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Default 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  
Old January 5th 07, 06:21 PM posted to rec.aviation.ifr
Sam Spade
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Default 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  
Old January 6th 07, 05:00 PM posted to rec.aviation.ifr
Paul kgyy
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Default LPV vs LNAV/VNAV?


Both of these options require a WAAS receiver, I presume?

  #4  
Old January 6th 07, 06:31 PM posted to rec.aviation.ifr
Sam Spade
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Default 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  
Old January 6th 07, 08:35 PM posted to rec.aviation.ifr
John R. Copeland
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Default 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  
Old January 6th 07, 09:51 PM posted to rec.aviation.ifr
Mike Adams[_2_]
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Default 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  
Old January 7th 07, 03:50 AM posted to rec.aviation.ifr
Andrew Sarangan
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Posts: 382
Default 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  
Old January 7th 07, 03:53 AM posted to rec.aviation.ifr
Mxsmanic
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Default 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  
Old January 7th 07, 05:48 AM posted to rec.aviation.ifr
Peter R.
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Default 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  
Old January 7th 07, 06:33 AM posted to rec.aviation.ifr
Andrew Sarangan
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Posts: 382
Default 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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