VDP on non-prec approached

[bdy85]

What are some short cuts you all use to come up with VDP's for time and Distance.

 

[Godvek]

Hope this is helpful...

Say your MDA is 550 feet and the local elevation is 150 feet. That leaves you 400 feet to descend.

Divide this number by 300 which gives you 1.3.
You should give yourself 1.3 NM from the runway to descend. Allow a 0.2 NM lead, so your VDP is 1.5 NM. Easy to figure out if on a VOR.

But say you are on a DME LOC for a 8,500 foot RWY (DME at far end of runway).
8.5 / 6 = 1.4 = runway distance in miles.
VDP for this is 1.4 + 1.5 = 2.9 NM

Then figure out VDP time for approach speed used.

 

[minitour]

What are some short cuts you all use to come up with VDP's for time and Distance.

...make the student do it

wow...I just realized I finally get to say "okay go preflight and I'll see ya in about 10 minutes"

-mini

 

[Kream926]

double post

 

[Kream926]

^ totally irrulevant

thanx

either way, if you made the student do it YOU would also have to know how to do it to make sure he is right

 

[Godvek]

I thought you were talking about me.

 

[minitour]

^ totally irrulevant

thanx

either way, if you made the student do it YOU would also have to know how to do it to make sure he is right

yep...I like the /300 thing...seems to me to be the easiest...there's one with time too...ah what is it

like...10% off of time from FAF-MAP?...I can never remember the time one...bad minitour...bad bad

-mini

 

[Godvek]

yep...I like the /300 thing...seems to me to be the easiest...there's one with time too...ah what is it

like...10% off of time from FAF-MAP?...I can never remember the time one...bad minitour...bad bad

-mini

You are a CFII? Sorry.

 

[minitour]

You are a CFII? Sorry.

Primacy...I was taught the /300 thing...

hind sight, I would have made myself learn both at first....

it's an embarassment for sure, but I learn somthing every day...maybe tomorrow I'll learn the time thing...

yeah! That's it...

Godvek, you've inspired me to learn the time VDP thing tomorrow. If it takes me all day, I'll have it mezmorized by tomorrow night, or I'll buy you a cookie. Thanks!

-mini

*disclaimer*
minitour not responsible for personal damages caused by consuming cookies - eat at your own risk

 

[Godvek]

Primacy...I was taught the /300 thing...

hind sight, I would have made myself learn both at first....

it's an embarassment for sure, but I learn somthing every day...maybe tomorrow I'll learn the time thing...

yeah! That's it...

Godvek, you've inspired me to learn the time VDP thing tomorrow. If it takes me all day, I'll have it mezmorized by tomorrow night, or I'll buy you a cookie. Thanks!

-mini

*disclaimer*
minitour not responsible for personal damages caused by consuming cookies - eat at your own risk

Hey, when you figure it out, let me know, I forget.


I usually just use my VSI.

 

[minitour]

Hey, when you figure it out, let me know, I forget.


I usually just use my VSI.

will do...thanks for the inspiration

 

[FracCapt]

wow...I just realized I finally get to say "okay go preflight and I'll see ya in about 10 minutes"

But, hopefully, that's not how you do things. When my students go out to preflight, I go out with them. That's part of the training, no matter how many times they've done it. Most of the time we just BS while they preflight....but, occasionally, they come up with a question they probably wouldn't ask had I not been there.

 

[minitour]

But, hopefully, that's not how you do things. When my students go out to preflight, I go out with them. That's part of the training, no matter how many times they've done it. Most of the time we just BS while they preflight....but, occasionally, they come up with a question they probably wouldn't ask had I not been there.

yep...as I sit here and think about it, I kind of feel like a babysitter during preflight. Watching over their shoulder as they go through the checklist, checking fuel levels, oil, other things that could kill me...

Then I find myself asking questions like "what kind of flaps/ailerons do we have?" "what does this do?" "what is that?" "can you fly without this thingy?"

I guess that can be good, but I'm worried my stus are gonna start thinking "man he doesn't even trust me to do a preflight..." and get all depressive...hopefully not...

Honestly it's not that I don't trust them, just that I want to answer any questions they might have right then and there...I guess that isn't a bad thing...

...but the realization of being able to say "go preflight" after all this time is kinda cool ...in a nerdy kinda way...im such a dork

-mini

 

[qmaster3]

I guess that can be good, but I'm worried my stus are gonna start thinking "man he doesn't even trust me to do a preflight..." and get all depressive...hopefully not...
-mini

NO, they will just find another CFI




Just F'n with ya brah

 

[minitour]

NO, they will just find another CFI




Just F'n with ya brah

eh...ya win some, ya lose some...

 

[Kream926]

...but the realization of being able to say "go preflight" after all this time is kinda cool ...in a nerdy kinda way...im such a dork
-mini

going into it with that mentality will get you in trouble. man im worried about ya and your future STU's.


Qmaster-

i second what you sais

 

[minitour]

going into it with that mentality will get you in trouble. man im worried about ya and your future STU's.

how so? am I being over protective? babysitting too much? not enough? ahh...

deep breaths deep breaths...it'll all be okay mini...

so just keep doing what I'm doing and don't say "go preflight" seems to be the general consensus? Stop asking them questions about the plane or answering questions during their preflight?

What do y'all do then?

-mini

 

[Kream926]

First off, you are an asshole sir. I don't think I'm alone in that opinion.

Second, I don't think judging his performance as a brand spanking new CFI based on a few posts on an internet message board is fair. A CFI is allowed to learn too....most people learn more in their first few hundred hours of instructing than in all their own dual recieved. Of course, since you are so perfect, you knew everything right off the bat.

never said i know everything, but to each his own. and thanks for callin me sir

 

[FurloughedAgain]

The second method for determining VDP is the time method (because we dont always have DME available).

Lets say that at 120 knots it will take you 2:00 to get to you missed approach point. The MDA on the approach is 400 feet above the ground.

If the MAP is over the end of the runway then you obviously need to determine a VDP.

Take the height above the ground at your MDA, drop the last digit. That leaves us with 40. Now take your 2:00 minutes and subtract 40 seconds.

1:20 seconds is your approximate VDP. It ain't rocket science but it will certainly give you a good place to start thinking "ok, once I pass this point I probably won't be able to safely make the runway even if I get it in sight".

If you choose a VDP and then use THAT point to begin your missed approach (climb ONLY!!! no turns until you reach the ACTUAL MAP) then you'll gain a little extra altitude by the time you reach the MAP. Helpful in mountainous terrain.

Good luck!

 

[Rez O. Lewshun]

Also.... consider visibility. IF your approach visibility minimums are 1 mile and your Planned [or pilot] Descent Point, PDP, (becuase only the FAA can calculate a VDP via TERPS), is 1.5 miles from the runway, and the reported visibility is acutally one mile, it is really useless to start the approach. Unless you want a look see.

 

[rchcfi]

Look around for a book called "Mental Math for Pilots". It's put out by ASA.

 

[Huggyu2]

For the professional pilots out there: how often do you have to go into a field that's no kidding IFR, and the only approach is a non-precision. It just doesn't seem to happen to me. Any place I go to that gets WX has an ILS. I can't remember the last time I had to shoot a non-prec approach to minimums and actually compute all the good stuff I learned about VDP computations.

 

[Yank McCobb]

Also.... consider visibility. IF your approach visibility minimums are 1 mile and your Planned [or pilot] Descent Point, PDP, (becuase only the FAA can calculate a VDP via TERPS), is 1.5 miles from the runway, and the reported visibility is acutally one mile, it is really useless to start the approach. Unless you want a look see.

Based on that logic, what's the point of even launching? How often are the flight visibility and that of the automated reporting system different? How often is visiblility from one direction different than from another? Etc...etc...There are many valid reasons to "look see" instead of just bailing.

 

[hawg2hawk]

For the professional pilots out there: how often do you have to go into a field that's no kidding IFR, and the only approach is a non-precision. It just doesn't seem to happen to me. Any place I go to that gets WX has an ILS. I can't remember the last time I had to shoot a non-prec approach to minimums and actually compute all the good stuff I learned about VDP computations.

Alaska. A lot.

 

[integrale]

To tag onto FurloghedAgain's response, which is correct, but didn't explain the logic behind the calculation is based on a 600 fpm descent. 600 fpm/60 sec/m= 10 feet per second. If your normal descent rate is nearer 800 fpm then the figure is more like 13 feet per second, of course the mental math gets a little trickier.