I apologize in advance if this is covered in one of the operating manuals, I haven't had time to actually browse through those yet (just picked up the 737 recently as my 2nd payware for FSX (owned many on FS2002/2004)).  

 

In following the tutorials I noticed the procedure to turn on vnav and lnav to "arm" them before takeoff.  I'm curious if it's acceptable procedure to arm vnav and turn on "hdg" hold (which actually turns on, not armed in the PFD) instead if I'm using FSX ATC which wants to vector you to your flightplan since it doesn't support SIDS.  Then of course I'd turn on the MCP in the air.  Or is it better to leave HDG off until in the air as well.  I have noticed some liveries like the basic Alaska one for the 800 winglets model has an equipment feature which automatically follows heading on takeoff vs. leveling the wings.  I know they don't all do that though.  

 

My purchase of the NGX has really gotten me interested in learning SIDS/STARS and I'm working on it (using charts.aero to look up SIDS/STARS and followed some training videos on youtube on how to read them, then just practicing) so I can eventually just jump to VATSIM.  For now though I plan to use FSX ATC and its lack of SIDS/STARS support until then and I just want to make sure I'm simulating procedures as best as possible in this situation.

Just like the rest of the MCP functions, it all depends on what you're trying to do.  If a controller says "after departure, fly heading 240," then having HDG SEL selected could be helpful for when you engaged the AP.  You could also just have the heading selected, but the function inactive so that you could select the function after engaging the autopilot.

 

There's no procedure for AP use.  It's a tool.  How you use the tool is up to you, your company SOP, and the situation at hand.

Just like the rest of the MCP functions, it all depends on what you're trying to do.  If a controller says "after departure, fly heading 240," then having HDG SEL selected could be helpful for when you engaged the AP.  You could also just have the heading selected, but the function inactive so that you could select the function after engaging the autopilot.

 

There's no procedure for AP use.  It's a tool.  How you use the tool is up to you, your company SOP, and the situation at hand.

 

Cool, that helps thanks  I think I was more concerned if it caused a functionality problem with the plane since VNAV/LNAV are actually just armed and HDG actually shows green on the PFD.  I think I was worried it would lock the rudder as I'm going down the runway although I didn't have that behavior when I tried it. I just wanted to be sure there wasn't the potential to run off the runway and crash or something.

 

 

I think I was worried it would lock the rudder as I'm going down the runway although I didn't have that behavior when I tried it. I just wanted to be sure there wasn't the potential to run off the runway and crash or something.

 

Glad to help.  The only thing it'll do is change the FD bars.  If you don't activate it, it'll command wings level.  If you do, it'll command a turn.  With the AP off, the FD indication is only a visual thing.

In following the tutorials I noticed the procedure to turn on vnav and lnav to "arm" them before takeoff. I'm curious if it's acceptable procedure to arm vnav and turn on "hdg" hold (which actually turns on, not armed in the PFD)...Alaska one for the 800 winglets model has an equipment feature which automatically follows heading on takeoff vs. leveling the wings.

Actually that is not procedure. If you are told to remain runway heading after departure or given an initial heading, then HDG SEL should only be engaged at or above 400'. 400' is normal minimum altitude for a turn (there are very rare exceptions to this).

 

To be honest, I am not 100% sure why or what would happen if you engaged HDG SEL on the ground, would it turn before 400'? I have never tried this in NGX, the sim or the real aircraft. I'm guessing Boeing are saying that they will not vouch for system behavior if you do engage HDG SEL on the ground. Boeing does say to ensure that the selected heading matches the runway track if the aircraft is fitted with the HDG SEL takeoff option (the Alaska option you mentioned), which suggests HDG SEL engaged on the ground could/will turn the aircraft early after lift off.

 

As an interesting aside, we have had occasion where LNAV has engaged from the armed mode on the ground, this happens occasionally, but LNAV does not initiate a turn below 400'.

Actually that is not procedure. If you are told to remain runway heading after departure or given an initial heading, then HDG SEL should only be engaged at or above 400'. 400' is normal minimum altitude for a turn (there are very rare exceptions to this).

 

To be honest, I am not 100% sure why or what would happen if you engaged HDG SEL on the ground, would it turn before 400'? I have never tried this in NGX, the sim or the real aircraft. I'm guessing Boeing are saying that they will not vouch for system behavior if you do engage HDG SEL on the ground. Boeing does say to ensure that the selected heading matches the runway track if the aircraft is fitted with the HDG SEL takeoff option (the Alaska option you mentioned), which suggests HDG SEL engaged on the ground could/will turn the aircraft early after lift off.

 

As an interesting aside, we have had occasion where LNAV has engaged from the armed mode on the ground, this happens occasionally, but LNAV does not initiate a turn below 400'.

Just curious, how do you handle "turn immediately"?

If I well remember VNAV activation on ground will be available with the "next step" of FMC software update (version11.0 U) that has been delayed (in real life), version 10.8 U shouldn't have this option..if you are departing according a SID (like happens in the most part of european airports) you can arm LNAV on ground but it's possible only if the first waypoint of the route lies between 5 degrees limits from the rwy centerline otherwise it won't arm and you've to arm it after having passed 400 ft AGL

 

Ciao

 

Andrea

No, VNAV prearm was available from 10.8 and became stable with 10.8A.

 

 

Just curious, how do you handle "turn immediately"?

Hey Kyle,

 

An immediate turn is at or above 400'. At 400', select HDG SEL, then set the desired heading.

 

There are exceptions to this 400' rule, but very rare and then are usually associated with engine failure scenarios. But even then the same procedure applies.

No, VNAV prearm was available from 10.8 and became stable with 10.8A.

 

 

Hi  Rostyslav,

Sorry I couldn't remember...

 

Ciao

 (Bolsoj Spasiba i Da Svidanja)

 

Andrea

 

 

Just curious, how do you handle "turn immediately"?

 

 

 

Hey Kyle,
 
An immediate turn is at or above 400'. At 400', select HDG SEL, then set the desired heading.
 
There are exceptions to this 400' rule, but very rare and then are usually associated with engine failure scenarios. But even then the same procedure applies.

 

That's Matt.  He's the one with the wealth of 737 knowledge.  I just try to keep up.

 

I will say, though, that as far as I know (from FAA-land), the only "rule" they have is to execute turns at or above a safe altitude, or as dictated by an ODP.  The 400' thing is just something that stems from how the manufacturer programmed in their idea of a minimum safe altitude, or the minimums as defined by the FAA for autopilot use.

 

 

That's Matt. He's the one with the wealth of 737 knowledge. I just try to keep up.

Sorry Matt!

 

 

 

I will say, though, that as far as I know (from FAA-land), the only "rule" they have is to execute turns at or above a safe altitude, or as dictated by an ODP. The 400' thing is just something that stems from how the manufacturer programmed in their idea of a minimum safe altitude, or the minimums as defined by the FAA for autopilot use.

Hey Kyle!

 

It comes from ICAO PANS OPS instrument procedure construction criteria. The 400' thing is actually 120m rounded up.

 

 

To be honest, I am not 100% sure why or what would happen if you engaged HDG SEL on the ground, would it turn before 400'? I have never tried this in NGX, the sim or the real aircraft. I'm guessing Boeing are saying that they will not vouch for system behavior if you do engage HDG SEL on the ground. Boeing does say to ensure that the selected heading matches the runway track if the aircraft is fitted with the HDG SEL takeoff option (the Alaska option you mentioned), which suggests HDG SEL engaged on the ground could/will turn the aircraft early after lift off.

 

We have a Juneau, Alaska departure called the FOX Departure. You take off from RW08 with 250 in the MCP HDG. On lift-off, you immediately pitch up to 20 degrees and then roll right to 30 degrees bank. The F/D doesn't follow this guidance for bank until you're through 400 feet. The F/D will give you the FAA/JAR-OPS/ICAO limits until 400, I believe, and in the correct direction, but it won't be a full 30 until 400 feet.

 

Basically, take that section from the FCTM and toss it.

We have a Juneau, Alaska departure called the FOX Departure. You take off from RW08 with 250 in the MCP HDG. On lift-off, you immediately pitch up to 20 degrees and then roll right to 30 degrees bank. The F/D doesn't follow this guidance for bank until you're through 400 feet. The F/D will give you the FAA/JAR-OPS/ICAO limits until 400, I believe, and in the correct direction, but it won't be a full 30 until 400 feet.

 

Basically, take that section from the FCTM and toss it.

Interesting. I had always just done the 400 feet turns also.

If memory serves, there are three turns:

Immediately: 50 ft

As soon as practicable: 50-400 ft

Turn: 400 ft

 

I can't find a reference for that other than ground school 1999. I'll dig some more.

Interesting. I had always just done the 400 feet turns also.

Yeah, that one is definitely a special procedure with FAA Approval.