What is an "FMS" STAR?

[AnthonyGA]

I was looking at a STAR yesterday (TRUDO1 for KMKE, to be specific) that had "FMS" in parentheses in the name. What does the FMS mean? I assume it has something to do with an on-board FMS, but I don't know exactly what it represents. Does it mean you have to fly the STAR with an FMS (only), or that it works best with an FMS, or what? The plate explicitly says that GPS and RNAV are required, but makes no mention of FMS requirements.

[Rainboe]

Standard Terminal Arrival Route. If you select Dep/Arr on the FMS, select the arrival airport, then the runway and approach in use, you will have the options of the several STARs available. You can usually guess which one is likely, and this will be confirmed later by ATC. It will then automatically load the full route to landing, obeying all height and speed restrictions automatically. You can simply confirm from the chart that all restrictions are correctly loaded, then automatically fly the profile, eventually to be peeled off on radar headings to suit ATC.

[AnthonyGA]

I'm still confused. Aren't all STARs already in the FMC database? If so, what would be special about a STAR that has "(FMS)" in the title? It's actually in the title (like GPS or RNAV in other STARs), implying that it's a special type of arrival, but it looks ordinary enough, and I can't imagine that it means "stored in the FMC" because all STARs are stored in the FMC already (right?).

Maybe it means that the STAR can only be flown with an FMS, but I don't see anything that couldn't be flown by hand as long as you have RNAV capability of some kind. It's mysterious.

[TheChitterneFlyer]

Most STARs are indeed within the FMS Database; however, there are different levels of navigational accuracy that can be achieved by an FMS. An FMS STAR (with waypoint LNAV and VNAV sequencing) might typically have several steering waypoints between two identified waypoints within the STAR; hence achieving a much more accurate approach path which might otherwise not provide an accurate autopilot coupled track between two single waypoints. Essentially, this provides more accurate track keeping; particularly within noise sensitive areas. Hope this helps?

[Rainboe]

What's loaded in the FMC is what the operator has purchased. There are obviously numerous 'modules' that are loaded up according to what the operator pays. Sometimes you find the database incomplete. It is not unknown to fly to a new destination and find the arrival airfield is not even loaded, let alone the STARs and SIDs. One then has to hash up what information you can. Not common, but smaller airlines operating to a wide range of airports can experience this. Indeed, capabilities of FMSs can vary according to the modules loaded into the computer, so we certainly don't assume everything is loaded!

[TheChitterneFlyer]

Indeed yes, individual companies will upload the FMS database with their own company routes, SIDs and STARs. Naturally, each airport have their own approach procedures, so not all airports will have a published FMS STAR. Major carriers have their own route navigation departments who are responsible for defining/editing either a recognised software package (such as Jeppesson), or for compiling their own software. There are strict regulations in force to ensure that these departments are approved by the regulatory authority... remember the Mt Erebus disaster; all because of a wrongly defined waypoint way down there in the Antarctic... all lives lost on a commercial tourist flight; all down to a decimal point! As for private use databases... you're on your own, and, should you not have a nice day because of a wrongly defined waypoint... beware, the subsequent board of enquiry by the regularory authorities will prosecute! However, it's likely that you'll be within Class A airspace and you shouldn't be there without the relevent rating anyway; that's why the regulatory authorities make the rules. That's enough from me. Tarra!

[KERDUNKER]

Do you perhaps refer to RNAV Stars, also I would hope that you would know if your intended arrival field was stored in the data base before engine start rather than embarass yourself on arrival.

[BOAC]

AGA - we may be able to get closer to an answer if you tell us where you 'saw' this?

[Caudillo]

I used to see these in aerads all the time - they're stars that can't be flown with reference to conventional navigation. It's been a while - but FRA perhaps, or maybe some in STR..?

[AnthonyGA]

The STAR I had actually been looking at was the TRUDO1 arrival for KMKE. Looking at it again, I notice that the instructions say "From over TRUDO to VEENA INT thence via the ATC assigned runway transition," and there are several paths on the plate that are labeled with transitions. So maybe ATC in this case says "descend via the TRUDO1 arrival with 19R transition," or something like that? Or perhaps it is automatically uploaded to the FMS? (My sim doesn't handle uploads and downloads, so I know almost nothing about that aspect of FMS operation.) Or maybe ATC gives you a runway and you select the appropriate transition on the FMC.

From what people are saying here, I understand that individual operators can actually cook up their own FMS databases? What would be the advantage? You'd still need the same fix and navaid data, and you couldn't really home-bake your own STARs, since they have to conform to the published ones (right?). At least this implies that you can modify the databases yourself (as an operator), which surprises me as I'd expect FMS databases to be locked by the vendor to make more money.

I also didn't know that FMS databases could be on a PAYG basis, but that part doesn't surprise me (money is everything). I guess the more you pay, the more you get in the database. If you are going somewhere that is unknown to the FMS, do you just enter all the routing data yourself by hand, or do you skip the FMS for the portion that it doesn't contain and just fly with the MCP, or by hand?

I know the Mt. Erebus problem was a navigation error, but not much more than that, I'll have to look it up again. I didn't realize that a FMS database error was involved.

[BOAC]

AGA - WHERE did you see this? EG Jeppesen, or what?

[AnthonyGA]

On AirNav (http://www.airnav.com). You can select an airport and there are links to download the current plates. I don't know the source of the plates, but I presume they come from the government. They are usually right up to date. I use it all the time for the sim.

[Rainboe]

Our company has sparse database loading as we fly to a wide variety of unusual and irregular destinations. It's not unusual to find your destination is not loaded at all, and doesn't 'exist' in the map database. Having tried to load the route before departure, one would then enter the Supplementary database and insert airfield position, then make up what approach you can for whatever runway you will use. That is all you need- it is a navigation convenience only- you get in to an airfield with standard instrument/visual techniques! Even if you discover inflight the destination is not in the database, rather than permanent preflight loading into the Supplementary database, you can just load a temporary position. It's standard aviation navigation techniques that count, not computer loading! Though some young pilots can be a bit lost without a computer to play with!

[BOAC]

AGA - I cannot establish the origin of those plates but I suspect that an 'FMS' STAR is the equivalent of an 'RNAV' STAR which can obviously only be flown if the RNAV waypoints are (or can be put) in the FMC database.

[AnthonyGA]

I didn't realize crews had that kind of flexibility; somehow I had assumed that airline crews were expected to follow SIDs and STARs, when these procedures are available, and that they weren't allowed (or at least weren't supposed to) "roll their own" procedures. I'm glad that they have the freedom to do that. Sometimes it seems like airline crews are drowning in procedures of various flavors. I also think that ATC in simulation might be a bit more gung-ho than the real thing.

I don't know the situation in Europe, although I've been told that European ATC usually assigns SIDs and STARs on the fly, at the time of departure or prior to arrival. I guess pilots have the option of refusing a procedure, as in the U.S.

BTW, I have since verified that the source of the plate is NACO.

[TheChitterneFlyer]

AGA,

Crews don't have that flexibility of building a STAR... a route, yes; but the STAR or SID is NOT! STARs and SIDs are clearly defined arrival/departure routes to regulate the flow of air traffic into or out of an airport. They're constructed by the local regulatory authority to avoid such areas of high terrain, noise sensitive areas, Royal residences... to name but a few, but the crew are more or less legally bound to follow the route as directed by ATC. "Kerbunker" is on the right track, it's likely to be an RNAV SID/STAR, which you cannot follow without the use of an FMC. You're therefore legaly bound by the instruction given to you by ATC. The only exception is if there is an emergency situation that prevents you from doing so; however, a cursory call to ATC to let them know that you aren't following the published SID/STAR is a must.

I mentioned that some of the major carriers do have navigation departments that are authorised by the regulatory authority to build SIDs/STARs, but it's really only a function of an amendment to those already programmed. The larger carriers obviously do have membership to the companies who do provide an amendment service (such as Jeppessen). I mentioned private operators, because just like any private pilot, you can programme your own GPS to carry out much the same job, but the accuracy won't be anywhere near an airline system that will typically have a 'Triple GPS' and 'Triple INS' position update feed to the FMS; nor have the output steering programme to the autopilot system that could follow rapidly changing waypoint database feeds.

It aint simple... and, unless you're only interested in attempting to use a flight simulation programme; don't mess with it in the real world! When ATC give you a STAR arrival; that's what it is... a clear instruction from ATC to fly a defined published route; a route which has been approved by the regulatory authority. An RNAV FMS-based turn between two chart identified points will typically have a dozen or so intermediate waypoints just to navigate you between two chart identified positions... all normally flown by coupling the autopilot to the FMS. It's very accurate when the system is also being updated by DME/DME fixing (or as accurate as it comes without normal VOR/DME stations and being updated by GPS/INS etc). My last airlne that I flew with wouldn't approve the aircraft or crew to follow RNAV approaches; despite our having Triple GPS/INS feed to the FMS. The aircraft equipment must also comply with the state regulatory requirements... just like CAT II, CAT III, CAT IIIA etc, etc; but that's another can of worms to open!

Bedtime for me!