Modern IFR Navigation
On July 3d, David Megginson wrote to the mailing list,
The airspace system is in the process of changing drastically, and I'm following it this summer by finally biting the bullet and installing an IFR GPS (Garmin GTN 650) and ADS-B transponder (Garmin GTX 345) in my Piper Warrior II. What this means that for the first time in the 15 years since I started flying in real life, I won't be able to use FlightGear to practice the IFR approaches I'm flying in real life. — David Megginson (Jul 3rd, 2017). [Flightgear-devel] RFD: FlightGear and the changing state of air
navigation .
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This article is about the discussion which followed that message, which focused heavily on modern IFR navigation.
Advanced RNAV Approaches
In the modern world, RNAV approaches are a lot more complex than following a magenta line and manually calculating a vertical speed or using VNAV. Modern RNAV approaches involve things such as "radius-to-fix" segments, which allow curved paths around mountains, which the aircraft can follow. One example is the RNAV (RNP) Y to 05R at Auckland: http://www.aip.net.nz/pdf/NZAA_45.3_45.4.pdf.
One thing that is very important moving into the future is the RF approach (radius to fix). Please read this:
https://en.wikipedia.org/wiki/Performance-based_navigation#RNAV_and_RNP_specific_functions... This style of RNAV approach is becoming more and more common, and FlightGear cannot yet simulate it. — legoboyvdlp (Jul 3rd, 2017). Re: [Flightgear-devel] RFD: FlightGear and the changing state of
air navigation .
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DME arc transitions still exist, and I enjoy flying them both in FlightGear and in real life. There are two important differences for the radial-to-fix transitions (as I understand so far, still studying up the new-to-me RNAV procedures):
— David Megginson (Jul 3rd, 2017). Re: [Flightgear-devel] RFD: FlightGear and the changing state of
air navigation .
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Are you wondering about the math to give you a guidance target for flying around a given point? Or are you wondering how to render the 'fly-to' indicator?
The first basically is the same as the Shuttle HAC intercept where Rdot (the derivative of the radius to the center point) in combination with R can be used as error for guidance and the second depends on your particular instrument - the Shuttle HUD shows a corresponding indicator (and so does the PFD) - but I suspect the instrument of choice of a GA aircraft will display it differently. So this should be possible to code by any aircraft maintainer without much fuss as far as I can see.— Thorsten Renk (Jul 3rd, 2017). Re: [Flightgear-devel] RFD: FlightGear and the changing state of
air navigation .
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The Route Manager should be able to handle most of the "magenta line" tasks, but it may be that the more complicated routing such as the RF approach, fly-by vs fly-over requires some new autopilot coding as you describe. — Stuart Buchanan (Jul 3rd, 2017). Re: [Flightgear-devel] RFD: FlightGear and the changing state of
air navigation .
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