LDA/Glide Slope Approach: Precision?

[pilotyip]

that is what I said

so what is your point, in C052 the LDA w gs is a NPA, just what I have said all along?

 

[avbug]

No, the general classification was changed from nonprecision. Some time ago, too. Regardless, the point is this: what your opspecs classify as approach as for purposes of currency and authorization, do NOT define what the approach is. Your opspecs could say the color blue is red, but that wouldn't change the color blue.

 

[Richie]

"Precision Like"

LDA Approach (Localizer-type Directional Aid):
[1.1, AIM 1-1-10, AIM 1-1-24, AIM 5-4-5, P/C Glossary, OpSpec C052 & 8400.10, Vol 3, Chap 1, Sec 5, para 83(B)
& FAA-H-8083-15 Instrument Flying Handbook]

1. A navaid used for nonprecision instrument approaches.

2. The LDA is of comparable utility and accuracy to a localizer but is not part of a complete ILS.

3. LDA course width is between 3° and 6° and thus provides a more precise approach course than an SDF installation.

4. The LDA course is not aligned with the runway, but STRAIGHT-IN MINIMUMS may be published where the angle between the runway centerline and the LDA course does not exceed 30°.
If this angle exceeds 30°, only CIRCLING minimums are published.

5. May have Glide Slope if noted. By definition qualifying it as a PRECISION approach. FAR 1.1 and the P/C Glossary define a “precision approach procedure” as ANY standard Instrument Approach Procedure with an electronic glide slope.

6. May incorporate a Decision Altitude(Height). DA(H) by definition is the decision altitude on a PRECISION approach (P/C Glossary).

7. An LDA with a Glide Slope could be considered a “PRECISION” approach due to the fact that it provides an “electronic glide slope” and may also incorporate a Decision Altitude (Height). However the definition of Localizer Type Directional Aid given in the P/C Glossary conflicts with these two statements, calling it “a navaid used for NONPRECISION instrument approaches.”
Of course the P/C Glossary does not define a “Localizer Type Directional Aid w/GS.”
From a Part 91 standpoint at least, I guess you get to choose whatever definition you like!

8. As an additional side note see AIM 1-1-24 — “Precision Approach Systems other than ILS, GLS, and MLS” — “Approval and use of precision approach systems other than ILS, GLS and MLS require the issuance of special instrument approach procedures…”

9. From an air carrier OpSpecs standpoint, an LDA w/GS is classified as a “PRECISION-LIKE” approach that provides vertical guidance but is not as accurate as a true precision approach. FAA policy is that even though a glide slope is available, the accuracy is not the same as an ILS, MLS, GLS, or TLS. OpSpec C052 lists “precision-like” approaches as Instrument Approach Procedures other than ILS, MLS, and GLS (i.e., NONPRECISION approaches), at least for air carriers.

10. From a practical standpoint an LDA with a glide slope normally brings you right down to the end of the runway, that’s pretty darn precise. Who cares if you have to make a slight jog just before touch down… you’ve probably done worse jogs at the end of many of your ILS approaches!

11. For Part 91, the only time the question of precision vs. nonprecision would become an issue is when choosing an alternate.

 

[pilotyip]

LDA w GS

So it is agrerd forair carriers the LDA w GS in a NPA, Right?

 

[PAIFA-a-joke]

Localizer Type Directional Aid- this is straight from the AIM's Pilot's/Controller Glossary.
A NAVAID used for nonprecision instrument approaches with utility and accuracy comparable to a localizer but which is not a part of the complete ILS and is not alligned with the runway.............. To me the AIM is saying that an LDA is not a precision approach, so I would say "no" and let the interviewer proove it to me, you always have the bible(FAR/AIM) to back ya up.

later...............

 

[flywithruss]

NON-precision

As we say down here in the South, "A cat can have kittens in the oven, but that don't make 'em biscuits."

In other words, just because this approach looks like an ILS, that doesn't make it precision! Forgive the non-PC analogy ... but have you ever walked behind a woman who looked really great from behind, but just when you were going to talk to her, she turned around and wound up looking like a troll? Same thing.

LDA approaches NEVER provide alignment with the runway centerline, by definition, whether that non-alignment is an angle of 10 degrees (a la LDA 6 ROA), an angle of 45 degrees (LDA/DME 19 DCA), or a lateral offset (12L and 30L approaches at STL). In most cases, LDA's are installed because a normal ILS or LOC installation does not work. At ROA, it is for terrain ... at DCA, for airspace, and at STL, to allow simultaneous approaches to close-parallel runways.

The fact that you are not aligned with and established on the runway centerline upon reaching DA (H) is the controlling issue here.

An LDA approach, with or without straight-in minimums published, with or without a glide slope, is a NON-PRECISION APPROACH, every day of the week, and twice on Sunday.

Tailwinds, y'all ...

R