A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Instrument Flight Rules
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

KJZI (Charleston Executive, S.C.) ILS RWY 9 DME Required



 
 
Thread Tools Display Modes
  #71  
Old March 18th 10, 02:58 PM posted to rec.aviation.ifr
Sam Spade
external usenet poster
 
Posts: 1,324
Default KJZI (Charleston Executive, S.C.) ILS RWY 9 DME Required

Padraig wrote:
Bob, sorry, substitute TDZ with MAP. My point is that generally a VDP
is measured from the end of the runway (beginning of TDZ) which is
often where the MAP is (on RNAV approaches).


Not exactly correct:

(1) For runways served by a VGSI (regardless of coincidence with final
VDA) , using the VGSI TCH, establish the distance from RWT coordinates
to a point where the lowest published VGSI glidepath angle reaches the
appropriate MDA.

(2) For runways NOT served by a VGSI, using an appropriate TCH from Vol.
3, chapter 2, table 2-3, establish the distance from RWT coordinates to
a point where the greater of a three degree or the final segment VDA
reaches the appropriate MDA.

My point is that a VDP has a threshold crossing height (TCH) as do all
vertically guided IAPs.

As to the MAP being at the approach end of the runway (AER), that is
correct only for NPAs whether LNAV, VOR, NDB, or LOC/LDA. The NPA MAP
will be prior to the AER when obstacles in the missed approach segment
preclude siting it at the AER.

Vertically guided approaches (with a DA/DH) always have their MAP at DA/DH.
Ads
  #72  
Old March 18th 10, 10:50 PM posted to rec.aviation.ifr
Padraig[_2_]
external usenet poster
 
Posts: 7
Default KJZI (Charleston Executive, S.C.) ILS RWY 9 DME Required

It would be nice to have a flight engineer figuring this out if I need
to make an approach.

Problem is, we sometimes need to determine where to let down from MDA
in relation to some known point. If we use the threshold (since we
generally have information on distance, i.e. MAP on RNAV approach), we
can use that as a VDP. If you use the 3 degree descent rate trick
(groundspeed x 10 / 2 = FPM), it's always going to err on the side of
being higher than you actually want to be since 300/ft per nm (what we
used for our VDP) is actually shallower, 2.8 degrees. So we'll arrive
at the threshold above our plan.

I guess the other thing, from a practical standpoint, is that we're
landing the aircraft visually. So we're not going to use our
predetermined descent rate/VDP point when we're flying the a/c over
the threshold at the TCH. We'll use the visual indications in the TDZ
(or VGSI) to get us on the ground.

In any case, the information you provide is good to know. Probably
more for design of an approach in the office, not practical
application in the cockpit. I would have to declare an emergency if I
had to do all of that math and fly at the same time!

PW

On Mar 18, 10:58*am, Sam Spade wrote:
Padraig wrote:
Bob, sorry, substitute TDZ with MAP. *My point is that generally a VDP
is measured from the end of the runway (beginning of TDZ) which is
often where the MAP is (on RNAV approaches).


Not exactly correct:

(1) For runways served by a VGSI (regardless of coincidence with final
VDA) , using the VGSI TCH, establish the distance from RWT coordinates
to a point where the lowest published VGSI glidepath angle reaches the
appropriate MDA.

(2) For runways NOT served by a VGSI, using an appropriate TCH from Vol.
3, chapter 2, table 2-3, establish the distance from RWT coordinates to
a point where the greater of a three degree or the final segment VDA
reaches the appropriate MDA.

My point is that a VDP has a threshold crossing height (TCH) as do all
vertically guided IAPs.

As to the MAP being at the approach end of the runway (AER), that is
correct only for NPAs whether LNAV, VOR, NDB, or LOC/LDA. *The NPA MAP
will be prior to the AER when obstacles in the missed approach segment
preclude siting it at the AER.

Vertically guided approaches (with a DA/DH) always have their MAP at DA/DH.


  #73  
Old March 19th 10, 01:43 AM posted to rec.aviation.ifr
Sam Spade
external usenet poster
 
Posts: 1,324
Default KJZI (Charleston Executive, S.C.) ILS RWY 9 DME Required

What I cited is indeed for the approach designer. But, some of it good
"background" info for pilots.

Padraig wrote:
It would be nice to have a flight engineer figuring this out if I need
to make an approach.

Problem is, we sometimes need to determine where to let down from MDA
in relation to some known point. If we use the threshold (since we
generally have information on distance, i.e. MAP on RNAV approach), we
can use that as a VDP. If you use the 3 degree descent rate trick
(groundspeed x 10 / 2 = FPM), it's always going to err on the side of
being higher than you actually want to be since 300/ft per nm (what we
used for our VDP) is actually shallower, 2.8 degrees. So we'll arrive
at the threshold above our plan.

I guess the other thing, from a practical standpoint, is that we're
landing the aircraft visually. So we're not going to use our
predetermined descent rate/VDP point when we're flying the a/c over
the threshold at the TCH. We'll use the visual indications in the TDZ
(or VGSI) to get us on the ground.

In any case, the information you provide is good to know. Probably
more for design of an approach in the office, not practical
application in the cockpit. I would have to declare an emergency if I
had to do all of that math and fly at the same time!

PW

On Mar 18, 10:58 am, Sam Spade wrote:

Padraig wrote:

Bob, sorry, substitute TDZ with MAP. My point is that generally a VDP
is measured from the end of the runway (beginning of TDZ) which is
often where the MAP is (on RNAV approaches).


Not exactly correct:

(1) For runways served by a VGSI (regardless of coincidence with final
VDA) , using the VGSI TCH, establish the distance from RWT coordinates
to a point where the lowest published VGSI glidepath angle reaches the
appropriate MDA.

(2) For runways NOT served by a VGSI, using an appropriate TCH from Vol.
3, chapter 2, table 2-3, establish the distance from RWT coordinates to
a point where the greater of a three degree or the final segment VDA
reaches the appropriate MDA.

My point is that a VDP has a threshold crossing height (TCH) as do all
vertically guided IAPs.

As to the MAP being at the approach end of the runway (AER), that is
correct only for NPAs whether LNAV, VOR, NDB, or LOC/LDA. The NPA MAP
will be prior to the AER when obstacles in the missed approach segment
preclude siting it at the AER.

Vertically guided approaches (with a DA/DH) always have their MAP at DA/DH.



 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Direct Air Executive BAe 125-800B @ Edinburgh Drew Malcolm Aviation Photos 0 August 18th 09 11:14 AM
Neoconservatives have taken over the Executive Branch NOMOREWARFORISRAEL[_2_] Naval Aviation 0 October 8th 08 11:57 PM
Boeing DreamLifter at the Charleston Air Show 4-26-08 Jim Austin Aviation Photos 0 April 27th 08 07:48 PM
ELT Required for all SSA sanctioned contests starting 2006 ELT Required for all SSA sanctione Steve Leonard Soaring 2 September 14th 05 03:49 AM
flying clubs in Charleston, SC Guillermo Piloting 1 June 22nd 05 02:50 PM


All times are GMT +1. The time now is 03:01 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright 2004-2018 AviationBanter.
The comments are property of their posters.