Flight Sim 2004 GPS 395 & 500

[Guest aerocub1]

Frequently the FAA changes and or adds new GPS approaches to airports. In Flight Sim 2004, is it possible to make these changes or additions to the GPS's?

[scott967 62]

Yes, but there hasn't been a tool developed to make it easy, so you have to do it by hand. The BGLComp SDK explains the XML to do it, but not really the hows and whys. The problem is that what MS did was incorporate the industry standard database format (ARINC 424), but not all of it is actually used. The format itself is an ARINC proprietary document, so I guess MS didn't want to provide too many details to avoid copyright issues.Fortunately, it is possible to disassemble the default AP9 files to look at the GPS approaches, and figure out the techniques, which are pretty straightforward for GPS approach types.Note that there are two flavors of GPS approaches, the GPS overlay and the full GPS, typically shown as RNAV/GPS at least in the US. You might also find some RNAV only approaches with other caveats applied, such as SAAR RNP or DME/DME. I don't think there are many new GPS overlay approaches being developed by FAA these days. Mostly they are the RNAV/GPS variety.There is a tool called "SDE" available for FSX which also can read FS9 files and will decode existing approaches. You can also use bglxml to do it for FS9 as well. Creating the new GPS approach typically involves creating new terminal waypoints and then designing the legs as shown in the paper chart. Note that you will generally find three types of waypoints on the paper charts:1. Enroute waypoints that serve as starting points for transitions. These in most cases will already exist in the FS9 AT9 files, so you don't need to create them. You can check using the FS9 map function to see if they exist. If they don't exist, you can create them in a separate file (not part of --nested within-- an airport element).2. Terminal named waypoints. These are the points with the 5-letter pronounceable names shown on the paper charts.3. Terminal unnamed waypoints. These are referred to as "tactical" waypoints and are used to help the computer sequencing of legs. These waypoints aren't too important in GPS approaches, except for the runway threshold which is automatically available for use in legs without having to create a new terminal waypoint entry. All new (or moved) terminal waypoints are "part-of" (xml code nested within) the "owning" airport xml element. Once the waypoints are all defined, you can build the approach. Most of these approaches are straightforward, with a "T" design allowing for three initial fixes. The legs are simply IF-TF-TF chained from waypoint to waypoint down to the runway threshold. Then the missed approach is typically CA-DF-HM, climb on runway heading to a defined altitude, then take an intercept course to the holding fix, then hold at that point until directed by ATC. I don't think AI know or care about GPS approaches so that isn't a problem.The main wrinkle will be if there is a course reversal "racetrack" on the approach, or sometimes the missed approach is more complicated.At least, this seems to work for me. The real expert on these fora is poster "jvile01" and you can search on his userid for more insight into approach coding.Finally, you may also find some RNAV SIDs or STARs that can be useful. You can add any new enroute waypoints for these as well. Then when you build a flight plan you can use the SID/STAR points even though ATC doesn't understand the concept. Attached is a file that adds two new RNAV/GPS approaches to KEWN New Bern airport. scott s..