What to follow" ATC or FMC?

[Gwhaarmann 3]

After takeoff with Lnav lighted at times the ATC directs a turn that disagrees with the FMC setting. what would be the correct course of acton,1. Follow the ATC and ignore the FMC2. Ignore the ATC and cancel the flight plan?GeorgeKPHX

[Stratox 22]

Always follow what the tower/departure tell you to do. The FMC has no authority! In FSX the ATC tends to be very iffy. I been using Radar Contact for some time now with FSX and the NGX with no issues.That can get you a permanent seat on the ground if you don't follow ATC instructions.

[scandinavian13 5,192]

ATC always, always, always.ATC sees the other planes/mountains/whatever you may hit. The FMC doesn't.Granted, the pilot has been given authority to do what is necessary if an ATC direction is deemed unsafe. The FMC hasn't, however. Try explaining that to the Feds...The FMC seems to have god-status amongst simmers, and I don't know why.

[chris41 0]

Came across a problem the other day with Radar Contact. The STAR chart showed I needed to be at or above 14000 at a specific waypoint due to terrain. Controller instructed me to be descend to 11000 30nm from the airport which was around where the charts showed me to be no lower than 14000. I requested a FL of 140 which was approved but 30nm from the airport the controller scolded me saying that I had missed my crossing restriction. If I had descended any lower than 14000 I would have been in the ground. Given the options the only thing I could do was request a higher FL from ATC. Radar Contact is great and I wouldn't fly without it but there are times when it can get on your nerves just a little. On a side note if anyone out there doesn't have Radar Contact I would highly recommend it.Chris Porter

[vololiberista 205]

The ONLY instrument you follow is TCAS. A TCAS RA overrides any ATC instruction.vololiberista

[ronzie 21]

The FMC is an aid for navigation. It can be used with ATC providing it is synced with waypoints sent in your ATC flightplan especially your FMC terminal database (SID-STARs). I use FSBuild 2.4 which exports to FS9, FSX, and PMDG FMC formats, among others.ATC rules as stated. Radar Contact allows optional flexibility in departure and arrivals, within 30 nm on departure and 40 nm on arrival. For arrival there is a hard coded descent crossing restriction at 40 nm out of 11,000 (FL110 in most non-FAA areas) or 12,000 (FL120) depending on your arrival direction to the runway.You can select to fly your own nav (and therefore unsing the FMC) preflight by selecting two modes in RC preflight for departure and for arrival after approach assigns your runway and issues your first vector by requesting an IAP at that time which effectively mutes RC so you can follow the remainder of the STAR.Where SIDs and STARs are runway specific but not known until flight time I use the waypoints common to all runways.I can't speak for other ATC products but this is how I sync RC ATC with the FMC terminal procedure database.I will note that as soon as ATC assigns a runway I enter the approach runway in the DEP/ARR section (but not the STAR unless needed) when getting approach vectors as it provides situational awareness for the arrival in the airport area. It also shows when you are about to intercept the LOC/ILS. With vectors I am on MCP control and use that indication to turn inbound before verifying the LOC/ILS ident and engaging APP.RC also has a "NOTAMS" option where in the departure and arrival zones you can deviate from ATC instructions.ATC rules and it is the responsibility of the pilot to comply no matter what navigation aids are used.With the caveat of current charts possibly not matching your installed scenery you can get free FAA terminal procedure charts from flightaware.com and for European Union airports you can get a free registration at Eurocontrol:http://ead-website.ead-it.com/publicuser/public/pu/login.jspto assist with picking appropriate navigation in airport areas including knowing which waypoints are common to all runways.

[fencer 16]

After takeoff with Lnav lighted at times the ATC directs a turn that disagrees with the FMC setting. what would be the correct course of acton,1. Follow the ATC and ignore the FMC2. Ignore the ATC and cancel the flight plan?GeorgeKPHX

Hi George,In real life, or if FS ATC was a REAL ATC (ie a controller with a real radar image), you'd want to follow ATC instructions unless you, as a captain, would see a dangerous situation develop and decide to disregard ATC instructions.But FS is a sim and FS ATC is less than perfect, especially in the approach/landing phase. It will typically take you around in some kind of huge, unreallistic DME ARC approach.So, unless you've switched over from FS ATC to something more realistic (third party or on-line flying), I would suggest to disregard ATC in the final phase of the flight, and if you have programmed a real STAR approach in your FMS, to follow your FMS. One way to do it is to cancel IFR and switch to visual and contact the tower but it is a compromise since, on a busy approach, it might create a collision risk with other traffic, or, if the wheather is really IFR, the tower may not allow to land at all (in that case, you can also disregard the tower...).Otherwise, you can elect to follow ATC but be prepared to visit the countryside, since FS ATC will take you along for a LONG ride...Anyway, with FS ATC, it's all a matter of comprmise.Hope this helps,Bruno

[ronzie 21]

There is an approach layer in both FS versions that may contain approach for some specific airports. AI and FS ATC may use these and whether VMC or IMC exists may affect this.These approaches can be seen in the approach view of the freeware airport afd editor called ADE9X.As far as syncing an FMC with ATC here is a topic sheet I published for Radar Contact users that may help using FSBuild 2.4 with FS ATC. Some of it might apply to FS ATC but I have only used that briefly in FS8 and never looked back. Pay particular qttention to otems 6 and 11:FSB tips:1. Include this line in FSbuild.cfg:NAVCHKDUPDIST=100This decreases the chance of using the wrong duplicate named local (to the airport) waypiont from a nearby airport. Local waypoint names are not exclusive. It decreases the database search when it is named in the route to within a 100 nm radius of your airport. You will find these in terminal procedures such as "D" number something within a SID or STAR to define a merge or turning point.2. When doing a Auto Generate (Route) be sure the SR (Stored Route) button next to it is "up" that is not highlighted. Auto Generate will use a stored route if found by default and most are out of date with old waypoints and terminal procedures. Having Stored Routes off forces it to search a path with fresh data. (Now off by default in version 2.4.)**REVISED 6/16/11** 3. FS Build database updates will be exclusively released through navigraph.com. It should be part of the FMC data line. For those not familiar with Navigraph each subscription term (cycle) includes multiple format downloads at no additional cost. This is very convenient for aligning FMC/navigation equipment databases with the flightplanner so among other things ATC data and your nav equipment data should match as you send a plan to ATC and then load it including terminal procedures into your FMC. The 2.4 upgrade includes the thirteenth cycle of 2010. The FSB upgrade is free to 2.x version users and is available via your order history on simmarket.com.4. Where an airport uses specific runways for different terminal procedures select the runway using an estimate based on weather and if the runway fits your aircraft requirements before doing the Auto Generate. This helps select the correct SID and STAR for the runway and direction of departure and arrival.5. After the Auto Generate and/or first build look at the map created to spot any obvious errors. In the route grid look for any sudden non-sensible changes in direction or extremely long legs not in the correct direction creating a zig-zag in the map. (See item 6 following to correct).6. Be aware there is an option you can set for each session titled "Build Route from Grid Table". It does not stick between sessions. This lets you build from an edited route grid that you may have modified without recreating the table with the same error on your next build/export. For example you might wish to drop an errant waypoint when proofing the map and rebuilding.7. Sometimes the name of a procedure (SID/STAR) does not match the name exactly in a published route and the procedure will not expand into its plan waypoints in the grid table. You can click on the arrow in the SID/STAR box to see what close name is in the FSB database. (Another reason to keep up with AIRACS.) For example KMSP has a current real such as this one:http://flightaware.c...DP/WAUKON+THREEbut the FSB database only has UKN2. (It does have UKN3 now with the latest available AIRAC update). If so in the route line just change UKN3 to UKN2 so it will expand. Here's a real route from flightaware.com for KMSP to KMDW:KMSP UKN3 DBQ CVA MOTIF3 KMDWthat can be pasted into the FSB route line. If UKN3 or MOTIF3 does not expand in the route grid to individual way points look in the upper part of FSB in the airport section dropping down the SID or STAR box to get the available version and substitute that label in the route line and rebuild. Note that the SID and STAR dropdowns may follow the chosen runway in certain areas.8. Sometimes it takes a second build to get the map to move and/or magnify. The mouse scroll wheel lets you magnify. Just click on the portion of the map you want to center on and scroll to magnify.9. If you click on a line in the route grid table to highlight it, the waypoint on the map will turn red. This is useful for finding errant waypoints that cause an error in the path. That line can then be edited or deleted and a rebuild accomplished with the build option to build from the route grid table.10. If you are running a weather program such as active sky, first build the route in FSB exporting to FS9 using an anticipated cruise altitude and specify the nearest aircraft profile. In AS get the weather you wish to use. (I always get the weather for the zulu time of the departure in FS since time of day affects weather characteristics). Import the plan into AS via the new route button, check the altitude and choose an appropriate true airspeed in knots (this is your no wind ground speed). Process the route. When it is finished click the button to print a hard copy of all. Use this AS navlog for METAR data at both ends and winds aloft and temperature aloft that can be used for FMC data. (You'll also get your estimated average wind at your specified altitude - handy for FMC data.) Leave AS running. Now go back to FSB and your chosen aircraft profile. Enter the surface temperature from your departure METAR, then estimated total taxi time, hold time, and extra time (sometimes called discretionary fuel). Now turn on again your FS9 export along with any FMC export you might use. Rebuild and you'll see the messages regarding the export completion. On the route selection on the left which brings up your route window select the navlog tab and click the .pdf to save the navlog in a file or the print button to get a hard copy so you can easily reference the estimated fuel and other data. This estimated fuel has now taken into account your winds aloft data - no need to enter it in FSB. Now that you have the hard copy and exported your route, you can first optionally save the plan by selecting flightplan window, then clicking the category tab, then select user category. Now click file, save from the menu bar. The name you might want to embellish. Click Save Route To User Flight Plans. For another session, you can recall this working plan and just build.11. If you are using an aircraft with nav equipment that has its own terminal data procedures in its nav equipment (think FMC) you might wish to use step 6 above to take out the waypoints of the terminal procedures keeping just the transition points and build and export with just them. This easily in most cases lets you select the SID and STAR assigned by ATC on your nav equipment by providing a clean legs list in your nav equipment. If you need ATC to monitor the waypoints of the terminal procedure than just export all. To keep ATC and you nav equipment in sync, you might consider importing the full plan into your nav equipment and not using your nav equipment procedure database.This is kind of long but through experience I've described some tricks I've used watching out for any pitfalls.Be sure to check the FSBuild forum for updates.