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11 votes
Accepted

Should IFR flight plans in the USA still have one waypoint per sector in 2023?

This is a holdover from the old HOST computer system that was installed in all enroute air traffic control facilities (ARTCC's) in the mid-70's. The original code was written in just 16MB of RAM. All ...
RetiredATC's user avatar
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10 votes

Does RNAV and RNP specify what type of longitudinal accuracy the system has?

It does, but it's a different issue than just positional accuracy. The goal of RNAV is to keep the aircraft within the confines of the specified airspace. Longitudinally, you will always be within the ...
Gerry's user avatar
  • 19.9k
9 votes

What are RNP and ANP in area navigation?

RNP is a numerical value that refers to the level of performance required for a specific published procedure. If the procedure has an RNP 10, then the on-board navigation equipment must be able to ...
Jimmy's user avatar
  • 2,839
8 votes

1. Why does the glide slope guide you down to 0.7NM away from the runway? 2. Best way to circle from 28 to active runway 36?

First off: it doesn't. The approach has no vertical guidance. Once you've passed JIBDO you can drop all the way to the MDA as quickly as your plane is capable of. Below the MDA there is no guidance at ...
Chris's user avatar
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7 votes
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Why is there a GPS/RNAV waypoint co-located with a VOR?

In the US, the FAA has done this alot, as in their long term plan to phase out a lot of the VORs. Doing that, they're preemptively just adding a Fix for procedures on top of the VOR so they don't have ...
slookabill's user avatar
  • 6,339
7 votes
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Why do RNAV airways exist?

RNAV freed aircraft from the airways that were already in place that may have zig zagged from VOR to VOR, but with the limitations of the ATC system based on human controllers, it is still desirable ...
John K's user avatar
  • 132k
6 votes
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Does ATC prefer ILS over RNAV?

As egid pointed out, pilots typically do not file a specific approach as part of their flight plan. ATC will decide what runways and approaches are in use based on the weather. As the pilots are on ...
fooot's user avatar
  • 73.4k
6 votes

Why are there no RNAV (ILS) approaches?

You are confusing some terminology. RNAV (GPS) approaches can have several different sets of minima. See the example RNAV (GPS) Y 28L at O'Hare: It has: LPV LNAV/VNAV LNAV sets of minima. LPV is an ...
Bronco6363's user avatar
6 votes

Why RNAV SIDs and STARs are RNAV 1 instead of RNP 1?

First of all, an RNP 1 procedure requires a GPS/ GNSS. And as you have said, it requires an inbuilt navigation monitoring and an alerting system. On the other hand, an RNAV 1 procedure does not. In ...
Anas Maaz's user avatar
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5 votes
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Are rhumb lines ever used as leg paths for RNP/RNAV?

No. The FMS does not use rhumb lines. All RNP/RNAV flight path legs are geodesics. The only exceptions are RF legs (a constant radius circular path about a turn center) and hold legs (a closed ...
Gerry's user avatar
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5 votes
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What is the lowest RNP approach requirement without being RNP AR?

In ICAO DOC 9905 (Required Navigation Performance Authorization Required Procedure Design Manual) you can find the following definition in Chapter 2.1 RNP APCH versus RNP AR APCH 2.1.1 RNP ...
miceagol's user avatar
  • 261
5 votes
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What are the "parts" of a SID procedure?

Yes, a SID can have three parts as you described. The runway transition defines the path from each runway to get to the common route section of the SID. All runways then share the common route section....
fooot's user avatar
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5 votes
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Are VOR airways being replaced by RNAV routes as VORs are decommissioned?

Short answer: there seems to be no general plan to replace airways with Q and T routes. The FAA originally proposed replacing them, but the final rule doesn't include it. You can review the source ...
Pondlife's user avatar
  • 71.7k
5 votes

What is the difference between a conventional and an RNAV holding?

A conventional hold based on legacy radio-navigation required overflying the hold fix on entry as guidance is only available inbound to the fix and your exact position is known at the fix (with some ...
Gerry's user avatar
  • 19.9k
5 votes
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Do GPS coordinates of a fixed point in space ever change?

The coordinates of a fixed point on earth do change, but they do change very slowly. WGS84 is a coordinate system. It is based on an ellipsoid that approximates Earth's shape. The surface of the ...
DeltaLima's user avatar
  • 83.5k
4 votes
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What is the reason to have LOC/VNAV landing method?

A VNAV with localiser approach is normally a backup to a regular ILS should there be a glide slope unserviceability. The use of VNAV to manage the vertical portion of the approach would allow the use ...
vectorVictor's user avatar
  • 1,229
4 votes
Accepted

How does CDI scaling transition from terminal to approach sensitivity?

Beginning 2NM prior to reaching the final approach fix of an activated approach, the GPS will smoothly taper down the CDI scale from 1-NM full-scale deflection (from the center) to 0.3-NM at full-...
Ryan Mortensen's user avatar
4 votes

What is GPS HIL in layman's terms?

The true position of an aircraft in flight can be measured, but the accuracy of any measurement is limited. The actual measured position is the actual true position plus the actual measurement error. ...
bogl's user avatar
  • 10.8k
4 votes

Why are there no RNAV (ILS) approaches?

The gist of your question is whether it is possible to couple RNAV with ILS? The following ILS chart of Cochin Airport (VOCI) is an ILS approach where Initial and Intermediate approach are executed ...
Shahab Mohd's user avatar
4 votes

Why RNAV SIDs and STARs are RNAV 1 instead of RNP 1?

Like a chart might state, RNAV 1 and then state that you require a GNSS. This essentially makes the procedure an RNP 1 procedure. Not correct. “RNAV1 – GNSS required” means that you can fly the ...
1pd's user avatar
  • 41
4 votes
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How to monitor MSA sector from an RNAV waypoint in the 737?

There is a way to do this in a 737NG using the FMC FIX page: 1 FIX Name Enter the desired fix. Valid entries are airports, navaids, waypoints or runway identifiers from the navigation database. [...] ...
Bianfable's user avatar
  • 55.9k
4 votes

Does RNAV and RNP specify what type of longitudinal accuracy the system has?

Unfortunately in the US many of the regulations are written to make it difficult to separate accuracy/integrity in the along-track direction from the cross-track direction. DO-229D claims this is &...
RealAnswersNotAI's user avatar
4 votes
Accepted

Why was the rate of part 121 LPV equipage projected to be so low, and has that projection come true?

Short answer: Money. Part 121 operators, i.e. airlines, are interested in profit and running an airline is a low margin business. Aircraft are very big capital expenses. They cost a lot every day in ...
Gerry's user avatar
  • 19.9k
4 votes

Do GPS coordinates of a fixed point in space ever change?

Conceptually, yes they change over time with respect to locations on the earth. Older mapping used a global model that assumed a static coordinate system, tied to the globe in one place (prime ...
BowlOfRed's user avatar
  • 5,611

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