VDP and Enroute Decent
12-03-2006, 08:31 PM
#11
Che Guevara
Joined APC: Aug 2005
Posts: 6,408
Originally Posted by TonyC
People don't seem to take it seriously enough for non-precision approaches. It's a good tool to use to know you better start getting ready to go missed eventhough your time has yet to expire.
12-04-2006, 06:30 AM
#12
Gets Weekends Off
Joined APC: Jan 2006
Position: 737 Captain
Posts: 777
I am with ToiletDuck. Keep it simple!
100 NM for the first 30,000 feet and then 3 NM for each 1000 feet thereafter. Add 1 NM for each 10 knots of tailwind and you will nail it every time.
I have never used or calculated a VDP outside the classroom.
100 NM for the first 30,000 feet and then 3 NM for each 1000 feet thereafter. Add 1 NM for each 10 knots of tailwind and you will nail it every time.
I have never used or calculated a VDP outside the classroom.
12-04-2006, 08:01 AM
#14
Prime Minister/Moderator
Joined APC: Jan 2006
Position: Engines Turn Or People Swim
Posts: 39,324
Some clarification:
-The 100 NM/ 30,000 rule is for enroute descent planning, not a VDP.
-A VDP (Visual Descent Point) is a charted point on a non-precision approach. It is identified often with DME, and you may not descend below MDA until reaching the VDP, even if you have the runway in sight. You must continue at MDA until passing the VDP. You do NOT have to calculate VDP, it is on the approach plate.
-A PDP (Planned Descent Point) is used like a VDP on a non-precision approach which does not have a VDP. It is not charted or required, but is calculated by the pilot for his own reference so he knows when to start to descend to achieve a 3 degree GS. The formula is 1 NM per every 300' AGL (at typical jet Vref) . If the MDA is 900' AGL, then the PDP would be 3 NM (DME or GPS) from the threshold. You can calculate a DME reference for the threshold distance by looking at the DME and distance numbers off the Jepp profile view.
-The 100 NM/ 30,000 rule is for enroute descent planning, not a VDP.
-A VDP (Visual Descent Point) is a charted point on a non-precision approach. It is identified often with DME, and you may not descend below MDA until reaching the VDP, even if you have the runway in sight. You must continue at MDA until passing the VDP. You do NOT have to calculate VDP, it is on the approach plate.
-A PDP (Planned Descent Point) is used like a VDP on a non-precision approach which does not have a VDP. It is not charted or required, but is calculated by the pilot for his own reference so he knows when to start to descend to achieve a 3 degree GS. The formula is 1 NM per every 300' AGL (at typical jet Vref) . If the MDA is 900' AGL, then the PDP would be 3 NM (DME or GPS) from the threshold. You can calculate a DME reference for the threshold distance by looking at the DME and distance numbers off the Jepp profile view.
12-04-2006, 08:55 AM
#15
Che Guevara
Joined APC: Aug 2005
Posts: 6,408
Originally Posted by rickair7777
Some clarification:
-The 100 NM/ 30,000 rule is for enroute descent planning, not a VDP.
-A VDP (Visual Descent Point) is a charted point on a non-precision approach.
-The 100 NM/ 30,000 rule is for enroute descent planning, not a VDP.
-A VDP (Visual Descent Point) is a charted point on a non-precision approach.
NDB
http://flightaware.com/resources/air...DB+RWY+35R/pdf
ILS/LOC if glide is disabled.
http://flightaware.com/resources/air...LS+RWY+17L/pdf
LOC
http://flightaware.com/resources/air...IAP/LOC+RWY+13
VOR
http://flightaware.com/resources/air...IAP/VOR+RWY+17
None of these are calculated. VDP lets you know how far out to go missed. You can do it by calculating time if you don't have dme or do actual distance. It simply allows you to plan for a rough 3 degree glideslope regardless of altitude. If I'm in the Merlin there is no need for me to keep looking for the runway if I'm going 135kts and .5dme. I might as well start getting ready to go missed. No reason to wait till the last second then be rushed into things. While it might only give you an extra 15 seconds that makes things that much easier. However I do find it most useful to knw when to come down. Slap whatever name you want on it, but the same equation exist. 6*gs for FPS descent and 3*alt for distance.
12-04-2006, 09:14 AM
#18
Prime Minister/Moderator
Joined APC: Jan 2006
Position: Engines Turn Or People Swim
Posts: 39,324
Originally Posted by ToiletDuck
No it's not.
NDB
http://flightaware.com/resources/air...DB+RWY+35R/pdf
ILS/LOC if glide is disabled.
http://flightaware.com/resources/air...LS+RWY+17L/pdf
LOC
http://flightaware.com/resources/air...IAP/LOC+RWY+13
VOR
http://flightaware.com/resources/air...IAP/VOR+RWY+17
None of these are calculated. VDP lets you know how far out to go missed. You can do it by calculating time if you don't have dme or do actual distance. It simply allows you to plan for a rough 3 degree glideslope regardless of altitude. If I'm in the Merlin there is no need for me to keep looking for the runway if I'm going 135kts and .5dme. I might as well start getting ready to go missed. No reason to wait till the last second then be rushed into things. While it might only give you an extra 15 seconds that makes things that much easier. However I do find it most useful to knw when to come down. Slap whatever name you want on it, but the same equation exist. 6*gs for FPS descent and 3*alt for distance.
NDB
http://flightaware.com/resources/air...DB+RWY+35R/pdf
ILS/LOC if glide is disabled.
http://flightaware.com/resources/air...LS+RWY+17L/pdf
LOC
http://flightaware.com/resources/air...IAP/LOC+RWY+13
VOR
http://flightaware.com/resources/air...IAP/VOR+RWY+17
None of these are calculated. VDP lets you know how far out to go missed. You can do it by calculating time if you don't have dme or do actual distance. It simply allows you to plan for a rough 3 degree glideslope regardless of altitude. If I'm in the Merlin there is no need for me to keep looking for the runway if I'm going 135kts and .5dme. I might as well start getting ready to go missed. No reason to wait till the last second then be rushed into things. While it might only give you an extra 15 seconds that makes things that much easier. However I do find it most useful to knw when to come down. Slap whatever name you want on it, but the same equation exist. 6*gs for FPS descent and 3*alt for distance.
Not sure what you're getting at here, but maybe I should have specified that not every approach has a VDP. If there is no VDP, then you can make your own PDP if you like, or not.
Jet drivers do tend to go missed if they don't see anything at the VDP/PDP, cuz they're not going to make a normal landing if they descend from the MAP.
12-04-2006, 09:39 AM
#19
Line Holder
Thread Starter
Joined APC: Nov 2006
Position: trying to survive
Posts: 91
thanks for the feedback guys its definitly helpful. Something I've also wondered about flying on an approach close to the missed approach point: If passing the outer marker on an ILS you lose an engine, is it better to secure the engine or just to continue? I would think securing would be better in case of a go-around, but in a higher speed aircraft I'm not sure (I'm talking about a propeller driven twin on this question as I'm sure the jet procedure is different). I've heard mixed reviews on that one, what do you guys think?
And again did anyone know what the brown diamonds are on a high enroute? haven't worked with those before....thanks
And again did anyone know what the brown diamonds are on a high enroute? haven't worked with those before....thanks
12-04-2006, 10:00 AM
#20
Gets Weekends Off
Joined APC: Jul 2006
Position: Soon to be Ex Dash-Trash
Posts: 270
Originally Posted by RJ Pilot
Select VNAV on your FMS. Set the altitude over the fix you want to be at. Follow the glidepath in you PFD. Its very simple.
