dale_willey

Programming Departure Altitude in FMC

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Is there a way to program an altitude after which the next leg of the flight plan is flown. Typically on SIDs you will see a starting airport, then an altitude in parentheses, e.g. (1800), followed by the first fix of the SID. Looking for a way to input just the altitude for non-SID departures.

 

Thanks

 

Dale

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Hi,

As far as I know, you cannot program altitude conditional waypoints in the FMC. These waypoints can only be programmed in procedures.

So you have to fly it "manually". You can engage the AP at 400ft with HDG SEL then change the heading or enter a Direct to in the FMC when passing the desired altitude, or fly without the AP.

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11 hours ago, dale_willey said:

Is there a way to program an altitude after which the next leg of the flight plan is flown. Typically on SIDs you will see a starting airport, then an altitude in parentheses, e.g. (1800), followed by the first fix of the SID. Looking for a way to input just the altitude for non-SID departures.

 

Thanks

 

Dale

The altitudes in parentheses are not VNAV constraints, they are points along the LNAV course.  In your (1800) example upon reaching 1800 MSL the active LNAV waypoint will switch to the next point on the legs page. 

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If you are interested you can create your own terminal procedures, or modify existing sidstar files.  They use a very simple and basic macro language explained in "Making 737NG Procedures" that should be in the AVSIM library.  A typical entry would be "HEADING 030 UNTIL 1800."

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13 hours ago, JoeDiamond said:

The altitudes in parentheses are not VNAV constraints, they are points along the LNAV course.  In your (1800) example upon reaching 1800 MSL the active LNAV waypoint will switch to the next point on the legs page. 

Yeah I get that. Is there a way to insert it? Looking for the macro on AVSIM without luck so far

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On 9/17/2017 at 6:57 PM, dale_willey said:

Is there a way to program an altitude after which the next leg of the flight plan is flown. Typically on SIDs you will see a starting airport, then an altitude in parentheses, e.g. (1800), followed by the first fix of the SID. Looking for a way to input just the altitude for non-SID departures.

 

Thanks

 

Dale

How would you use that for a flight?

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If the departing airport didnt have a SID, I'd use it as a "turn no earlier than" type point to allow for accelerating. I know I could just select HDG HOLD until an altitude before selecting LNAV. I'm just curious how to enter it since I see it in SIDs anyway

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As mentioned above, you can't. Such waypoints can be coded in the navigation database as part of a procedure, but there is no way to enter them manually.

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6 hours ago, dale_willey said:

If the departing airport didnt have a SID, I'd use it as a "turn no earlier than" type point to allow for accelerating. I know I could just select HDG HOLD until an altitude before selecting LNAV. I'm just curious how to enter it since I see it in SIDs anyway

Welcome to the forum. Please note that full names - first and last - are required in your posts here.

As others have said, it is not possible to do something like this. This reminds me a lot of the discussion on over-dependence on automation. It's so much easier to just fly the plane. Don't even bother with the complexities of the automation.

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12 hours ago, dale_willey said:

If the departing airport didnt have a SID, I'd use it as a "turn no earlier than" type point to allow for accelerating. I know I could just select HDG HOLD until an altitude before selecting LNAV. I'm just curious how to enter it since I see it in SIDs anyway

Hi Dale, in practical terms you would never do this because you are supposed to be flying the aircraft during that critical first few seconds of flight.  I assume most operators inhibit the selection of HDG and only take off wings level.  The pilot must intervene and push the HDG button to change heading after takeoff.  This generally happens above 400 AGL or higher if specified in the obstacle departure chart.

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10 minutes ago, downscc said:

I assume most operators inhibit the selection of HDG and only take off wings level.

I can't speak for other operators but ours give you HDG SEL when you press the TOGA button.  That option is probably more common than you think.

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6 hours ago, JoeDiamond said:

I can't speak for other operators but ours give you HDG SEL when you press the TOGA button.  That option is probably more common than you think.

Same. We don't have to select anything.

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