VDP on non-prec approached

[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.