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Captain Caveman

737 COURSE

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The COURSE setting on the MCP is used to provide track to or from a VOR navaid, or localizer, inbound as appropriate or outbound. It would be set to a radial of the tuned in VOR or localizer on your NAV 1 receiver. If under A/P control and you pushed the VOR/LOC MCP button or APP button, the aircraft will seek to merge with the radial you have dialed in the COURSE setting and then follow it. This radial is shown on the ND as a dashed green line.HEADING sets a direction to steer your aircraft in. In A/P mode when HDG is activated, the aircraft will turn to the direction dialed in on the MCP HEADING window. The HDG bug on the ND displays your setting with an attached pink line (I recall).

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Hello Ron, so are you saying the COURSE setting is critical to the VOR/LOC MCP function - that is, to both LOC and VOR? In the LOC case, what happens if I have COURSE on an abitrary setting and I'm flying on a heading that will intercept the localizer? Assume NAV1 is set to the ILS or LLZ frequency. Can you confirm that the aircraft turns onto the localiser regardless of the COURSE setting?I've never tried the VOR case yet (I'm still only at 1500' on this huge learning curve :-)), but I'm guessing this is where the COURSE setting is necessary to tell the aircraft which radial to turn on to. Thanks for your help.Geofff

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You may want to read some articles on basic IFR flying and use of VORs and ILSs before trying to use the 737 effectively. The difference between heading and course is a basic tenet of IFR flying and is sort of a prerequisite to flying the 737 correctly. There are some IFR lessons in FS2004 that go over the basics I think. FSX has some missions that explain it as well if you buy that next month...

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>Hello Ron, so are you saying the COURSE setting is critical>to the VOR/LOC MCP function - that is, to both LOC and VOR? >>In the LOC case, what happens if I have COURSE on an abitrary>setting and I'm flying on a heading that will intercept the>localizer? Assume NAV1 is set to the ILS or LLZ frequency. Can>you confirm that the aircraft turns onto the localiser>regardless of the COURSE setting?>>I've never tried the VOR case yet (I'm still only at 1500' on>this huge learning curve :-)), but I'm guessing this is where>the COURSE setting is necessary to tell the aircraft which>radial to turn on to. >>Thanks for your help.>Geofff If you don't set the course that mnatches the selected final app rwy you will get an FMC message ;-) (on the 737) try it..Best,Randy J. Smith

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Thanks Randy, yup, had the message many times because the FMC course is always different to the published runway heading - I think one's magnetic and the other true. So then I set the COURSE to what the FMC wants. But what if I don't? The FMC locks onto the localizer anyway, right, because it's transmitted as a narrow beam. Whereas if you're flying a VOR approach, the beam is omnidirectional and the A/P needs to know which radial to lock on to, and you need to set that radial in the MCP COURSE dial.What I'd like confirmed is that you don't need to enter a COURSE value for a localizer approach.CheersGeoff

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This bothered me too then I decided to play along.The COURSE is not important for tracking a LOCALIZER, because the localizer only has one "radial"; however, it is used to align the APPROACH display (which looks like a HSI indicator) such that the display course is displayed correctly. It also gets rid of the annoying message from the FMC.Many, if not most, ILS localizer courses in FS9 are off from the published charts due to errors in magnetic variation that have slowly accumulated since FS9 was released. The FMC doesn't actually know what the localizer course is within FS9 (determined by the facility data in the bgl file), but obtains this information from the airac data where it also gets frequency and runway information. The airac data from navdata is derived from DAFIF, which is current but I still notice many locations where the FMC localizer course is off by one degree from the chart. I haven't figured this one out yet but like I said, I've just decided to play along. The A/P APP will lock in on the localizer regardless of the COURSE setting.

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Thanks Dan, good to know I was on the right track. I missed the significance of the COURSE setting for the APPROACH display cos I never use it. I like to see where I am in relation to the runway so I stay in MAP view most of the time. As you know I'm trying to wean myself off the A/P for final approaches - is this where I'd make more use of the APPROACH display? Do you use it a lot?Geoff

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Geoff, don't know about the 737NG, but AFAIK, at least on some types, the course is used during autolands in a crosswind so the autoland system knows the runway heading to "kick it straight" to. At any rate, it's good practice to set the right course so the display on the EHSI is correct etc.Cheers,Martin

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I also generally handfly the final approach. I've used the APPROACH display but find it is totally redundant information with what is displayed on the left screen, so I also keep it in map view for situational awareness and use the primary flight display and the home for my instrument scan. My instrument scan is always centered on attitude and just about everything I need to execute an approach is right there next to it. I use the zoom 2D panel for approaches, but for takeoff I click on the PFD and pop it up to the left side of the windscreen. Just personal preferences.

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I looked at KSAN for reference where the magnetic variation is over 13 degrees east to compare the different methods of published data.The 2003 FAA IFR TERP airport diagrams and IAP plates both use magnetic heading/course data which match. Runway ID markings are magnetic rounded and divided by ten. That's why they change every few years due to the roughly .1 degree drift in magnetic variation every year. (The FAA facillities directory at the time did not show runway headings as far as I can see. The NIMA facilities directory does and it lists magnetic headings.) In FS the AFCAD shows runways as true course headings for setting the parameter (as in any scenery program) but then for display the mag heading is calculated and displayed as well.)I'll check again but I think I had the incorrect course once on the MCP and when I engaged approach after being on HDG following vectors (many times I do follow an IAP before that discussion starts :) ) the aircraft wandered off the correct heading for the LLZ merge.I am also not sure that a localizer outputs a single beam as homing on any VOR/LOC radial is a phasing based sensing, not signal strength peaking, or you would not know if you were left or right of the beam. This therefore requires a correct course setting for the desired reference for the phase comparison. An avionics person needs to answer this as I'm only an electronics tech. When switching to VOR/LOC or APP this is what is used with the difference in sensitivity needed (more for a localizer) calculated by the frequency setting as I recall.Of course in an LNAV approach where legal, the course setting is moot.You do not require an ILS procedure showing or loaded into the FMC to do a navaid approach. The data is there to use if you want it. In the US navaid approaches take priority where available and I do not think that rule has changed.

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On the 747, the course is set in the FMC on the nav radios page (e.g. 110.10/072). I would expect the 777 to be the same.Martin

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Thank you for the link.Then the COURSE setting seems to affect only the PFD centering indication but I'll check that next flight.Do you think they also phase the two signals as well for display purposes requiring the COURSE setting as a guide?I have been using the reciprocal COURSE on smaller aircraft for flying the outbound heading for a procedure turn, using HDG for the turn and setting the COURSE during the turn for inbound.(In another thread it is stated the 737NGs do not use PTs but I have located plates that show large turns to accommodate these heavier planes where terrain permits. Just including this before someone reintroduces this topic. Sometimes this is required for some ditch/canyon airports that require a descending hold or PT to get on the final vertical profile.)

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> Then the COURSE setting seems to affect only the PFD centering indication but I'll check that next flight.As far as I understand the localizer needle on the PFD should be centered even if you've got the wrong course set. The only thing the course setting should affect is the orientation of the deviation bar in the EHSI. However, even this should display the correct deviation information if the wrong course is set (unlike with a VOR).> Do you think they also phase the two signals as well for display purposes requiring the COURSE setting as a guide?Sorry, not sure I understand what you mean here... as far as I'm aware, ILS (unlike VOR) doesn't use phase differences. It just looks at the difference in strength between the two beams -- if the two signals are of equal strength, you're right on the localizer.> I have been using the reciprocal COURSE on smaller aircraft for flying the outbound heading for a procedure turn, using HDG for the turn and setting the COURSE during the turn for inbound.I guess using the reciprocal course should be fine... since it's basically the same as flying the back course of an ILS...Martin

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