What is a PDP?

[Steveair]

Does anyone know what a PDP is? I've heard guesses that it's a Precission Descent Point but I need a definate, 100% no doubt answer. If it is that, would the PDP just be GS intercept? Is it depicted anywhere?

 

[AlwaysLearning]

Could it be VDP? Visual Descent Point? Ive been out of instructing a while so PDP could be new term!?

 

[FarginDooshbahg]

How about Pilot Descent Point? It's like a VDP only not charted, but instead calculated by the pilots to be used like a VDP on a non-precision approach.

 

[Steveair]

How about Pilot Descent Point? It's like a VDP only not charted, but instead calculated by the pilots to be used like a VDP on a non-precision approach.

By George, I think he's got it...

 

[firstthird]

I've always heard it called a Planned Descent Point.

A technique where the pilot caculates a VDP based on a 3 degree descent from MDA to the TDZ. The idea is that if you see the runway at that point, good deal, descend and land. If you do not, you execute a missed approach since it isn't necessarily safe/comfortable to do a let down to landing from the actual MAP on many approaches (think VOR at the field and station passage is MAP).

 

[Steveair]

I've always heard it called a Planned Descent Point.

A technique where the pilot caculates a VDP based on a 3 degree descent from MDA to the TDZ. The idea is that if you see the runway at that point, good deal, descend and land. If you do not, you execute a missed approach since it isn't necessarily safe/comfortable to do a let down to landing from the actual MAP on many approaches (think VOR at the field and station passage is MAP).

Thanks for your time & help!

 

[Guitar Guy]

To calculate a PDP, you can take your MDH and divide it by 300. That will give you the distance from the runway at which to descend in order to maintain a 3-degree glideslope. This is handy if you have a DME that measures either up to or back from the threshold. For example, if your MDH is 450 ft AGL, your PDP is 1.5 NM (450/300) from the runway threshold.

Another, less accurate way to calculate a PDP/VDP is to take your time to the MAP and subtract 10% of the MDH. For example, if the time to the MAP is 2:57 and the MDH is 450 ft AGL, the time to the PDP is 2:12 (2:57 - 10% of 450, which is 45).

I hope this helps a little bit.

 

[Steveair]

That sure did / thanks guitarguy.

 

[potrack]

New terms are funny.

PDP?

I used to just say, "If a VDP isn't published...calculate your own"

Then I would ask the student, "Did you figure out a VDP?"

Funny how the one that you calculate yourself has a different name?

Next thing you know, they will say that a 'TOD' is derived from an FMS VNAV solution. If you figure out when to start your enroute descent yourself.....you have to call it something else.

 

[FarginDooshbahg]

I've always heard it called a Planned Descent Point.

Ooops. Yea, that's what I meant to say. Planned Descent Point. But the explanation remains the same.

 

[Swede]

PDP = Pilots Defending the Profession, an APA splinter group from the 90's that never attracted any followers.

 

[MD80PILOT]

Guys!!!!!! PDP means Pre Determined Point. It is used with different navigation planning procedures.

Ex: Drift down procedure when passing a mountain range. At a certain point prior to crossing one has to have reached a certain altitude in order to be able to meat the drift down (altitude loss) in the event of an engine failure.

 

[wmuflyguy]

Read the article "Brief This Approach" by Bob Norris...It was published in Airline Pilot Careers in March of 1997.

It covers how to brief an approach, runway lighting systems, and mental math at how to compute top of descents and PDP's.

GuitarGuy's explanation and method is exactly what is stated in the article.

 

[~~~^~~~]

PDP & VDP are concepts you learn and recite for checkrides and sim evals. Distance at 300 ft per mile and whatever fudge factor technique your examiner feels groovy with. Speed divided by 2, add a zero for decent rate.

When you are performing a non precision to a iced up, MU value runway, three years after your type ride that stuff tends to go by the wayside. If you don't know the power settings and the airplanes performance well enough to intuitively know "stable" bag it and go somewhere else. Or, call crew scheduling and tell them you are sick.

I've never thought that 1.52435 miles from the threshold in crap weather is the time for "higher math." But, if your training department wants to see VDP / PDP, placate them and go about your way. On line, it is about as useless as the over wing fueling procedure for your airplanes' center tanks.

 

[minitour]

Here's what I don't get about VDP.

Why does it matter?
Once you can descend from MDA to a "normal" landing, you do it and that becomes your VDP, doesn't it?

-mini

 

[FlyinTim]

Look In The Aim