Questions tagged [terps]

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32
votes
2answers
8k views

What does the snowflake with temperature symbol on an approach plate mean?

I've only seen the snowflake symbol with temperature listed on this one approach plate for KASE airport in Aspen, CO. I looked for it in the legend but didn't find it. Does anyone know what the ...
19
votes
1answer
805 views

Why would an approach be Cat A NA?

I was looking at the RNAV (RNP) 6 approach into Gunnison (KGUC) and noticed something quite strange: If the image isn't clear enough -- the approach is Not Authorized for approach category A aircraft ...
15
votes
1answer
5k views

Why is this VDP not authorized?

I have to admit that I’ve always kind of struggled with the Visual Descent Point (VDP) concept. Looking at the Terminal Instrument Procedures (TERPS) definition: “The VDP is a defined point on the ...
13
votes
3answers
7k views

When flying a circling approach, is it permitted to begin the visual circling segment prior to the final approach fix?

If it were a beautiful sunny VFR day and you were cleared for a circling approach, can you begin the circle prior to the final approach fix/circling DH in order to maneuver visually to land? Here are ...
12
votes
5answers
5k views

Are crossing restrictions on an ILS/LOC approach mandatory when flying on the glideslope?

Some "ILS or LOC" approaches have crossing restrictions that are shown before and/or after the final approach fix/glideslope intercept. Are these restrictions for the LOC only approach, or do they ...
9
votes
4answers
1k views

Why do the RNAV (GPS) approaches to KAPC not use the same missed approach procedure as the ILS/LOC approach?

While looking at the various instrument approaches for Napa Valley (KAPC), I noticed a discrepancy between the RNAV (GPS) Y/Z RWY36L missed approaches and the ILS/LOC RWY36L approach: Why is it that ...
8
votes
5answers
20k views

On a procedure turn, do you make the turn on the inside or outside of the procedure turn?

When flying a procedure turn like the one shown below, the first step is to fly outbound 039 degrees. When you turn inbound to 219 degrees, do you make that turn to the left or to the right? The left ...
8
votes
1answer
1k views

How do you determine whether you can us LNAV/VNAV minima on an RNAV approach?

If we look at this approach plate it has LPV DA LNAV / VNAV DA LNAV MDA CIRCLING I understand that if you have WAAS you can shoot the approach to LPV DA minimums. If you have only a GPS with a DME ...
8
votes
1answer
290 views

Why does obstacle clearance area splay outward instead of being a rectangle?

I am having trouble figuring out the logic behind the way that obstacle clearance areas are constructed. Take, for example, a departure procedure where Initial Climb Area is defined in TERPS (section ...
6
votes
1answer
840 views

What does the instruction “Climb heading [BEARING] to [NAVAID] 2.5 DME” mean?

I am examining FAA's Standard Instrument Departure Procedures (SIDs) and while reading their textual description, I came across this instruction from LGA's La Guardia Five Departure SID, for Runway ...
6
votes
0answers
302 views

Which US airport has the lowest circling MDH?

As I recently contemplated 14 CFR 135.223 and its implications, I began wondering about airports with exceptionally low circling minima. For a little context and background, the part of §135.223 that ...
5
votes
1answer
299 views

Why are the minima for Cat A higher than for other categories at KSEA ILS 16L?

I was looking at the KSEA ILS 16L approach (depicted below) and was wondering just why the minima are bumped up for Cat A aircraft (64 feet on both DA and HAT, as well as 200 feet of RVR). Thing is, ...
4
votes
2answers
318 views

KIBM RNAV (GPS) 10 — did I find a charting error, or what is the TERPS rationale for this?

I was looking at the RNAV (GPS) approach to runway 10 at Kimball, NE (KIBM): and was left wondering "How on earth could the straight-in visibility minima for approach categories C and D be lower than ...
3
votes
2answers
384 views

Why are there no RNAV (ILS) approaches?

While studying the PBN (FAA Order 8260.58A) and TERPS (FAA order 8260.3D) documents, I still have some trouble figuring part of the logic behind the naming and definitions of the published IAP Charts. ...
2
votes
2answers
143 views

PA/APV Glidepath Descent and Obstacle Clearance Slope's lowest point determination

I am studying the US Terminal Instrument Procedures manual (TERPS) and as I was skimming through the guidelines about Sloping Obstacle Clearance Surface, I came across the image below from section 2-1-...
2
votes
1answer
132 views

How much difference in heading/bearing between consecutive legs is “officially” considered a turn?

While examining FAA's TERPS manual (Order 8260.3D) and PBN manual (Order 8260.58A), I noticed two seemingly contradictory statements. TERPS 8260.3D Chapter 14. Departure Routes, 14-3-4 . Construct ...
2
votes
1answer
166 views

Non-precision approaches for which constant descents are not approved?

I noticed an interesting note -- circled in red pencil below -- on the KEEO RNAV (GPS) RWY 03 approach the other day: Why would the FAA apparently prohibit constant-descent final approaches to this ...
2
votes
0answers
29 views

Does a Navigation Specification characterize all legs of a terminal procedure?

I am studying the different parts of Instrument Flight Procedures, as they are described by FAA's manuals, such as the Aeronautical Information Manual, TERPS and Performance Based Navigation. For ...
1
vote
1answer
45 views

Is the arrival segment of an IAP in PANS-OPS the equivalent of FAA's feeder route?

In ICAO's manual 8168 ("Aircraft Operations"), the term "Feeder route" is never mentioned. Instead, it states: 8168 Volume II, "Approach Procedures": 1.2.3. Segments of the approach procedure. An ...
1
vote
0answers
57 views

Is airport's magnetic variation value used for terminal procedure design?

I am studying how instrument flight procedures are coded to ARINC-424 format, and since I was curious about the method used to determine the outbound/inbound magnetic courses, I checked the section ...
0
votes
1answer
39 views

What are early/inside and late/outside turns (see, e.g., PBN Manual Order 8260.58A) and when do pilots perform them?

While studying FAA's PBN Manual (Order 8260.58A), I came across the concept of early/inside and late/outside turn construction (Section 5-3. Turning Departures). For each of the possible cases, it ...