Vdp ?

[flyboyzz1]

So gearing up for an interview but have a question on VDP. I've talked to numerous people and have gotten two different answers and don't know which is correct as they both sound good. 1) You can not descend below MDA until you cross that point thus avoiding any obstructions. 2) It's a point that if you cross tells you the airplane may not be able to descend on a stable approach path to the runway and a missed may be necessary. Any help clearing these up would be greatly appreciated.

 

[BcPilot99]

So gearing up for an interview but have a question on VDP. I've talked to numerous people and have gotten two different answers and don't know which is correct as they both sound good. 1) You can not descend below MDA until you cross that point thus avoiding any obstructions. 2) It's a point that if you cross tells you the airplane may not be able to descend on a stable approach path to the runway and a missed may be necessary. Any help clearing these up would be greatly appreciated.

VDP is regulatory, cannot descend below MDA until crossing, even with field in sight.. to calculate take your HAT and divide by 300. There is a timing method to it to, but I am on spring break and poppin a cold one so I am to lazy to explain that one.

 

[flypixs]

Vdp

I understand that you can leave the MDA b/4 crossing the vdp. It is just a reference point. The Vdp gives you a glide slope of aabout 3 degree. For distance and time I have the following and it has worked just fine so far:
Distance - HAT x 3 / 100 = Vdp from end of rwy, HAT 415x3=1245/100=1.3 miles.
Time - HAT/10, 415/10=41 seconds.

Like I said that is how I do it and it works just fine. Compare is with approach plates which have a Vdp given and use the info I gave you. You will see that you come up with the same numbers

 

[BcPilot99]

I understand that you can leave the MDA b/4 crossing the vdp.

It is regulatory when on an approach ( just like a step down fix), so how can you legally descend below it?? ( please explain, maybe I am misunderstood)

 

[MarineGrunt]

It is regulatory only when published.

 

[BcPilot99]

It is regulatory only when published.

Yea, if not published it is a PDP. So that would make the VDP regulatory wouldn't it?

 

[flyboyzz1]

what is PDP stand for? So I guess the PDP would be to ensure proper path to the runway where a VDP cannot be descended before hand to ensure clearance from something below....right?

 

[shiznitobam]

Maybe I'm off here, and please correct me if I'm wrong, but I was under the impression that you descend from the MDA when the runway is in sight and you are in a safe position to land. Is it a good idea to use the VDP as that point? I think so; however, if the reason that you can't descend from the MDA prior to the VDP is for obstacle clearance then wouldn't that be a step down fix and not a VDP. I've always been under the impression that a VDP is not regulatory.

 

[BcPilot99]

I've always been under the impression that a VDP is not regulatory.

I was told it is, and at an airline interview you better say it is....


FLYBOYZZ1,

PDP = Planned Descent Point

 

[DC8 Flyer]

It is regulatory only when published.

And, I believe no AIM in front of me, if the airplane is eqiupped to ID the VDP (ie DME/GPS)

 

[BcPilot99]

And, I believe no AIM in front of me, if the airplane is eqiupped to ID the VDP (ie DME/GPS)

yea, but that would be a requirement to even conduct that approach (i.e. Radar or DME req.)

 

[SnowBoardBum]

The VDP is only regulatory when published.
If not published its the pilots responsibility to make sure the landing can be made in the touchdown zone using normal maneuvers and descent rates.

Right out of FAR 121.651

Sec. 121.651

Takeoff and landing weather minimums: IFR: All certificate holders.

(a) Notwithstanding any clearance from ATC, no pilot may begin a takeoff in an airplane under IFR when the weather conditions reported by the U.S. National Weather Service, a source approved by that Service, or a source approved by the Administrator, are less than those specified in--
(1) The certificate holder's operations specifications; or
(2) Parts 91 and 97 of this chapter, if the certificate holder's operations specifications do not specify takeoff minimums for the airport.
(b) Except as provided in paragraph (d) of this section, no pilot may continue an approach past the final approach fix, or where a final approach fix is not used, begin the final approach segment of an instrument approach procedure--
(1) At any airport, unless the U.S. National Weather Service, a source approved by that Service, or a source approved by the Administrator, issues a weather report for that airport; and
(2) At airports within the United States and its territories or at U.S. military airports, unless the latest weather report for that airport issued by the U.S. National Weather Service, a source approved by that Service, or a source approved by the Administrator, reports the visibility to be equal to or more than the visibility minimums prescribed for that procedure. For the purpose of this section, the term "U.S. military airports" means airports in foreign countries where flight operations are under the control of U.S. military authority.
[(c) If a pilot has begun the final approach segment of an instrument approach procedure in accordance with paragraph (b) of this section, and after that receives a later weather report indicating below-minimum conditions, the pilot may continue the approach to DH or MDA. Upon reaching DH or at MDA, and at any time before the missed approach point, the pilot may continue the approach below DH or MDA if either the requirements of Sec. 91.175(l) of this chapter, or the following requirements are met:]
(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and where that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;
(2) The flight visibility is not less than the visibility prescribed in the standard instrument approach procedure being used;
(3) Except for Category II or Category III approaches where any necessary visual reference requirements are specified by authorization of the Administrator, at least one of the following visual references for the intended runway is distinctly visible and identifiable to the pilot:
(i) The approach light system, except that the pilot may not descend below 100 feet above the touchdown zone elevation using the approach lights as a reference unless the red terminating bars or the red side row bars are also distinctly visible and identifiable.
(ii) The threshold.
(iii) The threshold markings.
(iv) The threshold lights.
(v) The runway end identifier lights.
(vi) The visual approach slope indicator.
(vii) The touchdown zone or touchdown zone markings.
(viii) The touchdown zone lights.
(ix) The runway or runway markings.
(x) The runway lights; and
(4) When the aircraft is on a straight-in nonprecision approach procedure which incorporates a visual descent point, the aircraft has reached the visual descent point, except where the aircraft is not equipped for or capable of establishing that point, or a descent to the runway cannot be made using normal procedures or rates of descent if descent is delayed until reaching that point.
[(d) A pilot may begin the final approach segment of an instrument approach procedure other than a Category II or Category III procedure at an airport when the visibility is less than the visibility minimums prescribed for that procedure if that airport is served by an operative ILS and an operative PAR, and both are used by the pilot. However, no pilot may continue an approach below the authorized DH unless the requirements of Sec. 91.175(l) of this chapter, or the following requirements are met: ]
(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers and where such a descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;
(2) The flight visibility is not less than the visibility prescribed in the standard instrument approach procedure being used; and
(3) Except for Category II or Category III approaches where any necessary visual reference requirements are specified by the authorization of the Administrator, at least one of the following visual references for the intended runway is distinctly visible and identifiable to the pilot:
(i) The approach light system, except that the pilot may not descend below 100 feet above the touchdown zone elevation using the approach lights as a reference unless the red terminating bars or the red side row bars are also distinctly visible and identifiable.
(ii) The threshold.
(iii) The threshold markings.
(iv) The threshold lights.
(v) The runway end identifier lights.
(vi) The visual approach slope indicator.
(vii) The touchdown zone or touchdown zone markings.
(viii) The touchdown zone lights.
(ix) The runway or runway markings.
(x) The runway lights.
(e) For the purpose of this section, the final approach segment begins at the final approach fix or facility prescribed in the instrument approach procedure. When a final approach fix is not prescribed for a procedure that includes a procedure turn, the final approach segment begins at the point where the procedure turn is completed and the aircraft is established inbound toward the airport on the final approach course within the distance prescribed in the procedure.
(f) Unless otherwise authorized in the certificate holder's operations specifications, each pilot making an IFR takeoff, approach, or landing at a foreign airport shall comply with the applicable instrument approach procedures and weather minimums prescribed by the authority having jurisdiction over the airport.

 

[SnowBoardBum]

This is out of the AIM :

2. Visual descent points (VDPs) provide pilots with a reference for the optimal location to begin descent from the MDA, based on the designed vertical descent angle (VDA) for the approach procedure, assuming required visual references are available. Approaches without VDPs have not been assessed for terrain clearance below the MDA, and may not provide a clear vertical path to the runway at the normally expected descent angle. Therefore, pilots must be especially vigilant when descending below the MDA at locations without VDPs. This does not necessarily prevent flying the normal angle; it only means that obstacle clearance in the visual segment could be less and greater care should be exercised in looking for obstacles in the visual segment. Use of visual glide slope indicator (VGSI) systems can aid the pilot in determining if the aircraft is in a position to make the descent from the MDA. However, when the visibility is close to minimums, the VGSI may not be visible at the start descent point for a "normal" glidepath, due to its location down the runway.