KDPA Du Page night approach procedures

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pstan

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Stan
I might be going to Du Page, KDPA. Anyone from the group have some insight on the following 2 questions?

1. For the Rnav 20L, there is a note "Procedure NA at night". Would this be because of obstacles close in below mda, and no visual glide slope indicator for runway 20L?

2. Why is night circling to runway 10 allowed for Rnav 20R approach, but not for Rnav 20L approach? The circling mda is the same for both approaches. Runway 10 has 3 degree vasis, though it appears it may be inop and still be useable at night.

Stan
 
1. Given there is no VDP, the lowest visibility is 1 mile, and it isn't approved at night. I am gonna venture to guess there is an unlit obstruction on the 20L approach that penetrates a 20:1 slope. The fact there is no VGSI is probably a factor too.

2. Short Answer: Because the 20L approach isn't authorized at night. Longer answer: Pretty much the same as the first question. The 20:1 obstacle. While flying the 20R approach and circling to 10, you would remain on the west side of 20R the whole time, so the 20L obstruction isn't a factor. Plus 10 has a VGSI. Runway 33 & 20L do not.
 
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Currently, runway 2L/20R (the primary longest runway) is under construction and will be closed until November or December 2014, so you definitely won't get the RNAV 20R.

The construction plan calls for intermittent closures of 10/28 as well, so be sure to check the NOTAMs before you depart.

I've been flying out of KDPA for the past couple years and the construction has caused some confusion this summer as several taxiways are also closed (ie, long roundabout taxi instructions).

The tower is open 24/7 and is typically quiet at night.

Hope you have a safe trip!
 
thanks for the info Steve.

Gucci, you wrote "While flying the 20R approach and circling to 10, you would remain on the west side of 20R the whole time, so the 20L obstruction isn't a factor."

First, I think the circling altitude ensures you have the required clearance from all obstacles. Secondly, I would have though if there were no circling restrictions, then you are allowed to circle any direction(s) you want. In which case it would be legal to be on the east side of 20R should you so desire. And so...other than the stated "NA at night", I do not see why a circling approach off of the RNAV 20R would be any different that RNAV 20L.
I see your point about question 1, thanks

Stan
 
pstan said:
thanks for the info Steve.

Gucci, you wrote "While flying the 20R approach and circling to 10, you would remain on the west side of 20R the whole time, so the 20L obstruction isn't a factor."

First, I think the circling altitude ensures you have the required clearance from all obstacles. Secondly, I would have though if there were no circling restrictions, then you are allowed to circle any direction(s) you want. In which case it would be legal to be on the east side of 20R should you so desire. And so...other than the stated "NA at night", I do not see why a circling approach off of the RNAV 20R would be any different that RNAV 20L.
I see your point about question 1, thanks

Stan
Click to expand...

In that I was speaking in a practical sense not a regulatory sense. True the circling radius would cover either direction.
The circling altitude gives you 300 ft of obstacle clearance...until you have to decent to the runway. The unlit obstruction is penetrating a 20:1 slope. but not a 34:1 slope. If thats the case, the only way for circling to that runway to be authorized at night is if the obstruction gets a light put on it, or you have a VGSI to guide you down to the runway.

It is probably a lot more than you want to know but how approaches are made is in 8260.3
 
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Yes Gucci, but this unlit obstacle is only a factor for 20L landing, not the circle to 10, as per the example given in my question 2 (original post).

Day or night, the circling approach mda gives a minimum of 300 feet above all obstacles within the circling area. The circling protected area is the same, whether it is the rnav 20L or rnav 20R approach. Hence, once you leave mda for descent for landing on 10, it hasn't really mattered obstacle clearance wise whether you flew the circ approach for rnav 20L or rnav 20R. However.....the notes seem to indicated you are not allowed to fly the rnav 20L circling approach, and land on 10 at night. The question remains, why? Certainly not due to unlit obstacles on the straight in approach rnav 20L.

I'm beginning to think there isn't really a good answer. Maybe for simplicity, it's easier to just say "procedure NA at night", and thus include the circling procedure too unfortunately.

Do you perhaps have your gradients mixed up?

Stan
 
From the AIM:

"i. Visual Segment of a Published Instrument Approach Procedure. Instrument procedures designers perform a visual area obstruction evaluation off the approach end of each runway authorized for instrument landing, straight-in, or circling. Restrictions to instrument operations are imposed if penetrations of the obstruction clearance surfaces exist. These restrictions vary based on the severity of the penetrations, and may include increasing required visibility, denying VDPs, prohibiting night instrument operations to the runway, and/or provide a “Fly Visual” option to the landing surface."

The obstacle penetrated the obstacle slope on some segment of the approach. Doesn't matter if you are gonna do a straight-in, side-step, circle. Rather than try to come up with ways around it, they have chosen to make the approach unavailable at night.

They probably thought:

Who would shoot a GPS approach to 20L and circle to 10 when they have a GPS approach AND an ILS to 10?

If the wind is favoring a 200 degree landing, 20R is longer and the GPS approach to 20R gets you 20 feet lower. Even lower if you are able to do WAAS which 20L doesn't have.

In the 8260 it says:

"Do NOT deny instrument approach procedures due to inability to mark and light or remove obstacles that violate Part 77 surfaces"

By making the approach available only during the day they are technically still providing you an instrument approach. Just limiting it's use.
 
steve_il said:
Currently, runway 2L/20R (the primary longest runway) is under construction and will be closed until November or December 2014, so you definitely won't get the RNAV 20R.

The construction plan calls for intermittent closures of 10/28 as well, so be sure to check the NOTAMs before you depart.

I've been flying out of KDPA for the past couple years and the construction has caused some confusion this summer as several taxiways are also closed (ie, long roundabout taxi instructions).

The tower is open 24/7 and is typically quiet at night.

Hope you have a safe trip!
Click to expand...


And to put in my 2 cents. The tower is extremely helpful and accommodating. I usually fly during peak hours and never had an issue. You should have no problems, and like Steve said, at night its quiet.
 
Gucci, "Who would shoot a GPS approach to 20L and circle to 10 when they have a GPS approach AND an ILS to 10?"

Actually, that was exactly what was on the DPA atis. If the weather permits, I think it allows an easy airspace deconfliction with the other chicago airports. And circle to 10/28 fits in well for aircraft hangared at the north end. I think Charheep and Steve have seen that regularly, perhaps they will confirm for you.

Just like Teterboro, the VOR A approach was often the one assigned, yet of course there are straight in approaches at TEB to the runways published, yet not normally assigned unless weather prevented the VOR A. Same for the ils 06 circle to land 19, t'was a procedure to be expected at TEB.

Re "Visual Segment of a Published Instrument Approach Procedure...penetrations of the obstruction clearance surfaces exist"

I think you are referring to the 20L straight in again. I am not. I refered to runway 10 since the original post, and have been refering to runway 10 in each of my follow ups. There is vasis, is there not? And no night restrictions for a straight in nor most circling approaches to this runway? No obstacles in the visual segment here (again, runway 10, NOT runway 20L).

"The obstacle penetrated the obstacle slope on some segment of the approach. Doesn't matter if you are gonna do a straight-in, side-step, circle. Rather than try to come up with ways around it, they have chosen to make the approach unavailable at night."

For the approach in question 2 of post 1, rnav 20L circle to land 10, where could an obstacle possibly penetrate the "obstacle slope"?

Anyone?

Not from MDA to commence circling (250 feet minimum obstacle clearance here for LNAV), and not during the circling procedure at the circling MDA (minimum 300 feet for Cat A aircraft here). Note: the circling minima provides protection above all (thats ALL) obstacles, with the specified distance, even those that may exist for other runways in the visual segment. This 300 feet in the circle procedure is there until starting a normal descent to land on runway 10. So....where can obstacle clearance be compromised off an RNAV 20L circ approach but not off an RNAV 20R circling approach to rwy 10???? This was the original question in post 1

Yet it is "NA at night".

Sorry if I sound mad, or irritated. I'm not.
 
steve_il said:
Currently, runway 2L/20R (the primary longest runway) is under construction and will be closed until November or December 2014, so you definitely won't get the RNAV 20R. !
Click to expand...
Why does the runway closure affect the approach being available? Is there not a circle to land option or if a pilot were to request it with the intent to go missed for practice?

I know I have shot approaches at airport where the runway for that approach was not available to land and it was made clear that I would not be cleared to land, but the approach was fine.
 
Scott, I don't see any notams that the Rnav 20R is N/A, so I would expect one could get the approach with the runway closed. ATC/Tower may have some other thoughts, I'm not sure.
 
For what it's worth, today I tried to shoot the practice ILS 9 at KARR. The runway was closed but I requested the approach anyway. Controller stated they received new guidance yesterday that prohibits them from approving approaches to runways that are not available. He did clear me to transition his airspace from west to east, however.

I don't know if this is a local or nationwide thing or if the controller was just feeding me a line of BS, but that's what I was told about 4 hours ago.
 
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