Jump to content

Sign in to follow this  
johanfrc

Coordination problems in the FMC (B737)

Recommended Posts

I have some major problems in the FMC.I would like to start a flight from Christchurch, New Zealand.In the "POS INIT" page I'm getting my own position. It show something like "S43*******, W173*********" You know how the position is written.Then I inset the "REF AIRPORT". Pressing NZCH and push the button nest to "REF AIRPORT". But the FMC says the coordination for NZCH is "S42********, W172********".Then I'm going to the "RTE" page, And once again I press NZCH into the "ORIGIN" and then the airports is showed on the "navigation display". It shows that the airport is placed about 160 kms north west of the real position of NZCH.I can take some screenshots of it if you want.I have tried other airports all over the world, and they are also being displayed in the wrong position.I have reinstalled the PMDG planes once, and installed the newest AIARAC and the newest SID/STAR for NZCH. But It's still showing the error.Can anyone help me, so I can get it working again.


AIG co-admin, AIG flightplanner, AI repainter and AFCAD designer.

Share this post


Link to post

The current airac airport data is "NZCH-43.489444 172.534444" When I checked the location of Christchurch, New Zealand in Wikipedia it came up a coordinate that is very close.<>I'm not sure what is happening here; however, I'm don't think the IRS readout is a result of the airac data but instead due to how you are initializing the current position. To be honest, I never bother with this because inertial nav is not modelled in the 737NG. I always start with the RTE page and enter the origin and destination ICAO codes and go from there.Maybe some screen shots would help. I'm trying to imagine how the nav display looks when it is putting the airports in the wrong place for all airports... how can you tell? Is it because you are on the airport but the airport symbol is not at the same location? What about the navaids (VOR stations) or waypoints (fixes), are they also in the wrong place? Interesting problem.


Dan Downs KCRP

Share this post


Link to post

Hmm... News. I have tested a flight from Wellington (NZWN to NZCH) and choose a NDB "OD" as part of my route. Following the FMC it should have a poistion in the middle of the mountains on the South Island of New Zealand . In reality i's placed north east of NZCH. And to get it even more strange then the FMC says that rwy 02 at Christshcurch is placed in the wrong position for "OD". And it's the same place NZCH chould be placed.Attch#1: The plane is placed on RWY02 in NZCH. As you can see the NZCH is far away.Attch#2: Where the FMC says NZCH is placed and where the NDB OD is positioned. Even though the OD shold be placed at the end of ILSRWY20 at NZCH.


AIG co-admin, AIG flightplanner, AI repainter and AFCAD designer.

Share this post


Link to post

I figured this would be interesting. I'll be back at my FS9 location in a couple of hours and I will try to duplicate this and maybe we can figure it out.By the way, forum rules require we sign our real name to our posts.


Dan Downs KCRP

Share this post


Link to post

>>By the way, forum rules require we sign our real name to our>posts.Thanks. It's updated now. I'm not very much on this forum so I don't konw all the rules.


AIG co-admin, AIG flightplanner, AI repainter and AFCAD designer.

Share this post


Link to post

Johan: Sorry, I couldn't duplicate your problem. I created a new flight with a PMDG 737-700 at NZCH Runway 2... FS9 puts me right in the right place at S43:29.84/E172:31.35 (FS9 coordinates). On the POS INIT page it shows as Last Pos some place in the USA, which is correct. When I enter NZCH as REF AIRPORT I get S43:29.4/E172:32.1 (FMC coordinates from airac data), which is correct. Then I go to the RTE page 1/2 and enter NZCH as ORIGIN and the airport symbol is right on the tip of the airplane symbol on the nav display.I also selected RNW 02 on the departures screen and placed OD as the first fix of the RTE and it lines up straight ahead at 12 nm.I am using AIRAC 0708 data from Navigraph.I believe you earlier mentioned you entered the REF AIRPORT and you got "NZCH is "S42********, W172********" which is wrong. If that is not a typo then your problem is your AIRAC data.Here's a couple of things to check:While sitting on Runway 2 do Shift+Z and compare the FS9 coordinate with the correct coordinates (S43:29.84/E172:31.35). This confirms that the scenery is correct.. we expect this but it's called closing an assumption.Next, open file /FMCWP/NAVDATA/airports.dat with any text editor (Wordpad will work) and search for NZCH... you should have the following line (it's line 55 in my editor): NZCH-43.489444 172.534444This will verify your navdata is okay.I'm looking forward to hearing if the second check above works.


Dan Downs KCRP

Share this post


Link to post

Have been checking now. RWY02 at NZCH is almost the same position as you: S43:29.82/E172:31.36.The NAVDATA was a little different, but nothing serious.I'll try to remove the FMCWP folder, and install the newest AIRAC again.


AIG co-admin, AIG flightplanner, AI repainter and AFCAD designer.

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  
  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
  • Donation Goals

    AVSIM's 2020 Fundraising Goal

    Donate to our annual general fundraising goal. This donation keeps our doors open and providing you service 24 x 7 x 365. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. We reset this goal every new year for the following year's goal.


    2%
    $705.00 of $25,000.00 Donate Now
×
×
  • Create New...