PMDG 737 altitude restrictions

[molleh 451]

i haven't had any problems with the 737 busting altitude restrictions (SIDs or STARs) but it does frequently break speed restrictions on SIDs for whatever reason. seems like maybe the MSFS engine modelling is a bit aggressive/responds faster than the real ones would and this results in the aircraft shooting up in speed too fast for the pitch up to compensate for it.

1 hour ago, Mace said:

Let me ask you guys this.  If I have a SID dialled in, with the waypoints progressively increasing in altitude...and I have one waypoint that says "at 17000"...should I be setting 17000 in the MCP on climbout?

I think (as I recall) ATC had cleared me thru 31000 feet, and I might have had 31000 feet in the MCP.

This may be the reason for the departure busting of 17000, but I'm not sure how it /should/ be done.

no, it should level off for restrictions and continue to the set MCP alt when possible.

[Stearmandriver 2,333]

1 hour ago, molleh said:

no, it should level off for restrictions and continue to the set MCP alt when possible.

Well... maybe. Depends what vertical flight guidance mode you're in. If you're in VNAV, then no need to set intermediate altitudes in the MCP.  If you're in level change or VS, then absolutely set the intermediate altitudes. 

[molleh 451]

47 minutes ago, Stearmandriver said:

Well... maybe. Depends what vertical flight guidance mode you're in. If you're in VNAV, then no need to set intermediate altitudes in the MCP.  If you're in level change or VS, then absolutely set the intermediate altitudes. 

yeah, i figured that was assumed. my bad.

[Mace 1,964]

@molleh you assumed correctly, I was in VNAV mode unless I'm mis-remembering it.   So @Stearmandriver I will have to fly this SID again and see if I get the same result.  Thanks for the info

[threexgreen 3,160]

I departed out of KLAS and arrived at KIAD and it didn't bust any restrictions, neither altitudes nor speed restrictions.

It seems to me however that LNAV isn't following the magenta line all to well. This is old news, but for some reasons it seems worse to me than in P3D. Crossing several waypoints it went too far at first before reducing bank instantly to a more appropriate bank angle, and sometimes it even kept swinging left, right, left, right, ... until eventually settling for a stable bank angle. I can definitely say this never happened in P3D. Since they will be updating LNAV I would assume the current LNAV code is the one they've been using all this time, so why would this be worse in MSFS with the same code?

[Cpt_Piett 4,869]

1 hour ago, threegreen said:

why would this be worse in MSFS with the same code?

It doesn't make sense. Would think that with the same code you get the same behavior. 

Just came back from a flight into NZQN Queenstown and the -700 managed the RNP approach quite well. There was one incident due to user error, when I went into approach mode way too early, and the plane descended below the STAR ALT restrictions. After realizing that I went back into VNAV PTH and everything was fine. 

[CaptainNick 575]

2 hours ago, threegreen said:

I departed out of KLAS and arrived at KIAD and it didn't bust any restrictions, neither altitudes nor speed restrictions.

It seems to me however that LNAV isn't following the magenta line all to well. This is old news, but for some reasons it seems worse to me than in P3D. Crossing several waypoints it went too far at first before reducing bank instantly to a more appropriate bank angle, and sometimes it even kept swinging left, right, left, right, ... until eventually settling for a stable bank angle. I can definitely say this never happened in P3D. Since they will be updating LNAV I would assume the current LNAV code is the one they've been using all this time, so why would this be worse in MSFS with the same code?

Lots of users have reported similar issues, and it turns out they have some of the assistance settings turned on (usually unbeknownst to them). Upon re-turning off all the assistance options at PMDG's suggestion they found the plane follows the line very well. Worth a look. It would not be the first time MSFS turned on a setting without someone doing it themselves.

[threexgreen 3,160]

17 hours ago, CaptainNick said:

Lots of users have reported similar issues, and it turns out they have some of the assistance settings turned on (usually unbeknownst to them). Upon re-turning off all the assistance options at PMDG's suggestion they found the plane follows the line very well. Worth a look. It would not be the first time MSFS turned on a setting without someone doing it themselves.

Assistance settings are all off here. On my flight today it worked better. It also didn't bust any altitude or speed restrictions.

[Langeveldt 294]

Does the descent/ascent initiate automatically when in VNAV mode or must I press something?  I get cleared to a new flight level, and I always press the ALT INTV button, which has worked for me, but then I guess I am busting tolerances. 

[Cpt_Piett 4,869]

33 minutes ago, Langeveldt said:

Does the descent/ascent initiate automatically when in VNAV mode or must I press something?  I get cleared to a new flight level, and I always press the ALT INTV button, which has worked for me, but then I guess I am busting tolerances. 

If you have VNAV and LNAV active and select an altitude lower than your current one, the plane should commence descent without user input when it reaches the TOD marker on the ND. 

[Fiorentoni 4,450]

2 hours ago, Langeveldt said:

Does the descent/ascent initiate automatically when in VNAV mode or must I press something?  I get cleared to a new flight level, and I always press the ALT INTV button, which has worked for me, but then I guess I am busting tolerances. 

Unless you are talking about the T/D (which does not seem to be the case, since you talk about new flight levels), you have to press alt intv when the aircraft has already levelled off (though when you are still climbing/descending, just turn in the new altitude and you are good, no need to press anything). You can also choose LVL CHG, but this will disengage VNAV.