View Full Version : Easy and accurate VDP using a calculator.
Dadanawa
11th Oct 2016, 10:23
You need the three highlighted figures in the diagram below and the constant which is 106.13.
VDP = 687➖55➗3.5➗106.13. = 1.7 nm
Minus, Divide, Divide.
Comments welcome.
http://i779.photobucket.com/albums/yy71/Dadanawa/IMG_1647_zpsrpima7nr.jpeg (http://s779.photobucket.com/user/Dadanawa/media/IMG_1647_zpsrpima7nr.jpeg.html)
FullWings
11th Oct 2016, 11:29
I thought it was: “Divide, divide, minus, multiply, add” or is that only for 3-engined aircraft?
safelife
11th Oct 2016, 11:39
We don't VDP. We do CDFA.
Continuous descend to a DDA, continue to land, or go around.
Level offs during approach aren't allowed since a loooong time in my place.
bingofuel
11th Oct 2016, 15:32
MDA 650' above runway , 3 deg slope, 300ft per mile, just over 2 miles, knock of a bit for the 3.5 deg slope, call it just less than 2 miles is good enough for me!
Intruder
11th Oct 2016, 16:52
...or just add the 1.2 and 0.5 in the profile view...
is this something from the former Soviet Union?!
Denti
12th Oct 2016, 01:04
Not really, VDP was taught at ATCA as well. Before CDFA was the norm.
Citation2
12th Oct 2016, 02:09
There is no VDP , it has to be flown CDFA and to be treated like an ILS.
If you want to locate the missed approach point laterally, it is already there for you .M is written in the vertical profile which is also the missed approach point for the LOC approach.It is 1.9 NM from ISAB
mustafagander
12th Oct 2016, 09:23
Let's not get too scientific.
300ft/mile is close enough for 3* G/S, a bit less for a steeper one, a bit more for a shallower one. We're trying to get into the visual slot so let's look out the window and use quick mental calculations for what they are intended, gross boo-boo protection.
Let's pretend to be pilots guys and girls, not technicians.
Citation2
12th Oct 2016, 09:45
Why are you guys trying to calculate something depicted on the chart ? 1.9 NM from ISAB
Alright to make things clearer , there are 2 arrows UP ( representing the missed approach point) indicated in the vertical profile . The closest to the runway located at around 0.5 nm from threshold corresponds to DA for a full ILS
The arrow with a M indication located at 1.9NM from ISAB is the location of your missed approach point when flying a localiser procedure. This is where you go around if visual references have not been established , Also it is the point where you should continue , if visual contact has been established , hence VDP.
Why make things complicated?
But it seems like VDP is not understood at all. VDP concept was established for OLD procedures where you could have the missed approach point located beyond the 3 degrees path , or beyond a deCent point to continue descent , which would inevitably lead to unstabilised approach should you decide to continue , for instance you could find Missed Approach Point over threshold on some old dive and drive procedures. Imagine flaps full gear down , leveling off until the threshold , seriously don't you think you will end up unstabilised ? Hence there was a requirement to establish a VDP that coincided with the normal decent
And this VDP was your new missed approach point . VDP was developped to permit stabilisation criterias .
Where the missed approach point coincides with the normal continuous descent , there is no need of VDP as the missed approach point itself , M , is a VDP , it is when you reach MDA , from there on , if visual , you will continue a normal descent to landing .