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sade050

FMC and LNAV

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HELLO EVERY ONE :)

so i decided to make a flight plane got my fmc setup right . turned both flight directors set my alt crus speed : v2

but LNAV wont arm , so i did some google searcher and i found 

 

 

There are a number of conditions for the LNAV to light. I think one of them is that the first waypoint be no more than 5 degrees off from the runway heading.

 

here is my departure 

GB3bn81.jpg

i think i have found the issue, but i m stuck both airports  dont have sids nor stars

how to align the depart route with the runway and make a soft turn ( curve )?

 

i m using FC commander and i did get the same result with the 737ngx fmc.

 

Anis

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Since no one has responded yet, I will suggest that you can just takeoff and when safe to do so manually turn, or use heading select to turn, so you are heading directly to the first waypoint and then select LNAV . Alternatively you could create your own 1st waypoint a mile or two (whatever is reasonable) off the end of the runway in order to satisfy the 5 deg requirement.

 

I'm sure others much more knowledgeable on this then I will respond eventually.

Al

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I would just "force then course" to BABOR during preflight:

 

  1. On the LEGS page, select BABOR
  2. It should now be in the scratch pad
  3. Put BABOR as the top or first fix
  4. Don't execute
  5. On the bottom right, put in the course to BABOR, approx 195
  6. NOW execute

This should give you the ability to use LNAV on the departure.

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how to align the depart route with the runway and make a soft turn ( curve )?

 

As mentioned in the other threads, you should really fly the tutorials.  There are other autopilot modes than LNAV.  More specifically, for airports without SIDs (and even for a lot of them that do), you depart on heading select.  Depart runway heading on heading select, and then turn the plane using heading select towards your initial waypoint.  Then select the waypoint by bringing it to the top of the legs page.  How to do all of this is explained in the tutorials.

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On the bottom right, put in the course to BABOR, approx 195

The bottom right of what?

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The bottom right of what?

 

Hi Michael,

 

on the bottom right of the scratchpad. So, first you type BABOR in the scratchpad, on the legs page, and you line select it as the first waypoint. The "EXECUTE" command will light up, do not execute. On the same page, on the scatch page, you enter say 190, the radial you want the NGX to fly to BABOR, and line select key 6 right, on the bottom right that is.

 

As a general rule, not every airport has a SID out of it, some in Europe request a Z flight plan, where you start off with a VFR flight plan, up to a waypoint, and then proceed IFR, or, and this is much more common in the US airspace, you take off and are vectored to a waypoint, usually a VOR, where your Jetroute starts. In the latter case, you won't file a a SID, as there is none, but you will fly on vectores, using the Heading Select function on the MCP.

 

Hope this clears it out a bit for you,

 

Enrico

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I would just "force then course" to BABOR during preflight:

 

  1. On the LEGS page, select BABOR
  2. It should now be in the scratch pad
  3. Put BABOR as the top or first fix
  4. Don't execute
  5. On the bottom right, put in the course to BABOR, approx 195
  6. NOW execute

This should give you the ability to use LNAV on the departure.

works like a charm

 strange thing i didn't hear V1 Vr V2 warning , and i have my take off settings setup

Anis

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i think i have found the issue, but i m stuck both airports dont have sids nor stars

how to align the depart route with the runway and make a soft turn ( curve )?

Generally speaking, in these cases do not use LNAV for the first turn after departure. Most airfields without a SID or STAR will have an airport NDB or VOR that will be a waypoint on an airway that will join up with your planned route. In such cases, the FMC will be setup in the RTE page as DIRECT <NAVAID> <AIRWAY> <WAYPOINT>. This can look a little strange, but this is usually the most appropriate as ATC depature clearances will often be of the nature 'turn left/right intercept airway (or radial to/from a navaid) climb to alt/FL.

 

If such an airway does not exist, then just program the FMC so that there is a direct leg from the navaid (or airport if no navaid) to your first enroute waypoint.

 

Once that is set up, depart using heading select, above 400' use HDG SEL to point the aircraft at a intercept course for that leg (intercept about 30 deg if possible). You can use the FMC LEGS page to setup up an intercept by bringing the first enroute waypoint to the top, enter the track from the airport to the way point in the bottom right (should be preset by default) and execute. Then when the wings are level and pointing at the magenta line you can engage LNAV and it will automatically capture the course and fly the rest of the route.

 

This is a realistic approach to the problem and generally the most practical and flexible method.

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on the bottom right of the scratchpad

 

Thanks for the information.

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works like a charm

 strange thing i didn't hear V1 Vr V2 warning , and i have my take off settings setup

Anis

 

You have to make sure that the takeoff callouts are selected in the 'settings' for the repaint that you are flying...my guess is that they weren't. If it happens for all the repaints that you fly then you might have a problem.

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