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PMDG question

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Anonymous
February 22, 2005 12:40:24 AM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

Before boB says anything I *know* there's an Avsim forum for this but I can
never remember my password and, anyway, you guys and gals are a much
friendlier bunch!!! ;0))

To those PMDG 737NG fliers amongst us - I programme a flight in the FMC and
everything appears fine. So how is it that every time after starting its
descent the overhead indicator "off scheduled descent" lights up and closer
to the destination the FMC reports "descent path unachievable" when it
calculated the descent path in the first place! What is going on or what am
I doing wrong/not doing? Any suggestions would be appreciated. :0))

Iain

More about : pmdg question

February 22, 2005 1:10:01 AM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

IAIN SMITH wrote:

> Before boB says anything I *know* there's an Avsim forum for this but I can
> never remember my password and, anyway, you guys and gals are a much
> friendlier bunch!!! ;0))
>
> Iain
>

Why would I say something? I didn't know there was an AVSIM forum for
that aircraft. Are you sure it wasn't Bob you were thinking of?

--

boB

U.S. Army Aviation (retired)
Central Texas - 5NM West of Gray Army Airfield (KGRK)
Anonymous
February 22, 2005 2:03:53 AM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

you guys and gals are a much
friendlier bunch!!! ;0))

Hey... that wasn't very friendly... :) 

--
Best Regards,

Tom Allensworth
Publisher,
AVSIM Online
Flight Simulation's Premier Internet Resource!
-------------------------------------
http://www.avsim.com
email: tom@avsim.com
-------------------------------------
See the rankings of your favorite Sim
Web Sites:
http://www.avsim.com/pages/rank_complete.html
"IAIN SMITH" <iainsmith.rugby@btinternet.com> wrote in message
news:cvdkg8$laf$1@hercules.btinternet.com...
> Before boB says anything I *know* there's an Avsim forum for this but I
> can never remember my password and, anyway, you guys and gals are a much
> friendlier bunch!!! ;0))
>
> To those PMDG 737NG fliers amongst us - I programme a flight in the FMC
> and everything appears fine. So how is it that every time after starting
> its descent the overhead indicator "off scheduled descent" lights up and
> closer to the destination the FMC reports "descent path unachievable" when
> it calculated the descent path in the first place! What is going on or
> what am I doing wrong/not doing? Any suggestions would be appreciated.
> :0))
>
> Iain
>
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Anonymous
February 22, 2005 2:05:01 AM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

bob or Bob, or boB,

PMDG's support forum is on AVSIM. Now you know. :) 

--
Best Regards,

Tom Allensworth
Publisher,
AVSIM Online
Flight Simulation's Premier Internet Resource!
-------------------------------------
http://www.avsim.com
email: tom@avsim.com
-------------------------------------
See the rankings of your favorite Sim
Web Sites:
http://www.avsim.com/pages/rank_complete.html
"boB" <akitaREMOVECAPS77@excite.Icom> wrote in message
news:Z_sSd.28657$Bx5.23742@fe1.texas.rr.com...
> IAIN SMITH wrote:
>
>> Before boB says anything I *know* there's an Avsim forum for this but I
>> can never remember my password and, anyway, you guys and gals are a much
>> friendlier bunch!!! ;0))
>>
>> Iain
>
> Why would I say something? I didn't know there was an AVSIM forum for
> that aircraft. Are you sure it wasn't Bob you were thinking of?
>
> --
>
> boB
>
> U.S. Army Aviation (retired)
> Central Texas - 5NM West of Gray Army Airfield (KGRK)
February 22, 2005 3:18:03 AM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

Tom Allensworth wrote:

> bob or Bob, or boB,
>
> PMDG's support forum is on AVSIM. Now you know. :) 
>

Thanks Tom... :) 

--

boB

U.S. Army Aviation (retired)
Central Texas - 5NM West of Gray Army Airfield (KGRK)
Anonymous
February 22, 2005 4:19:07 PM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

On Mon, 21 Feb 2005 21:40:24 +0000 (UTC), IAIN SMITH wrote:

> Before boB says anything I *know* there's an Avsim forum for this but I can
> never remember my password

Why do you need to "remember your password?" Once you've logged in ONCE,
you should be able to return without logging in again, provided you haven't
disabled the cookie for avsim...

Bill
Anonymous
February 22, 2005 9:51:12 PM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

"boB" <akitaREMOVECAPS77@excite.Icom> wrote in message
news:Z_sSd.28657$Bx5.23742@fe1.texas.rr.com...
> IAIN SMITH wrote:
> Why would I say something? I didn't know there was an AVSIM forum for
> that aircraft. Are you sure it wasn't Bob you were thinking of?

Sorry boB, it must be Bob then! :0))

Iain
Anonymous
February 22, 2005 9:53:35 PM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

"Tom Allensworth" <tom@REMOVETHISavsim.com> wrote in message
news:tNtSd.3199$Ba3.838@newsread2.news.atl.earthlink.net...
> Hey... that wasn't very friendly... :) 

Only joking Tom - I'm sure they're a similar minded group to this one! :0))

Iain
Anonymous
February 22, 2005 11:56:57 PM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

On Mon, 21 Feb 2005 21:40:24 +0000 (UTC), IAIN SMITH wrote:

> To those PMDG 737NG fliers amongst us - I programme a flight in the FMC and
> everything appears fine. So how is it that every time after starting its
> descent the overhead indicator "off scheduled descent" lights up and closer
> to the destination the FMC reports "descent path unachievable" when it
> calculated the descent path in the first place! What is going on or what am
> I doing wrong/not doing? Any suggestions would be appreciated. :0))

VNAV disengaged on ya, huh? :-)
Well...the first thing you should do when you get that message is open the
DES page of the FMC. There you can check the programmed descent profile of
your flight. Then check that data with the data on your MCP and PFD.
It's been a while since I last had this problem, but I believe this occurs
when your altitude is higher or lower than your descent path profile reads.

The easy way to quickly fix that is to either guide the plane manually to a
lower altitude or set a fitting altitude in the MCP and click LVL CHG.
When you're back on target, engaged VNAV and the FMC should fly the descent
profile from there.
Don't forget to set the flaps and v-speed in the INIT REF before making the
descent. (I always set that as soon as I'm at my FL).

I got this from the FMC tutorial at the PMDG website:

=====================================================
The FMC descent capabilities provide for descent planning and execution.
A planned descent can only exist when a lateral route containing at least
one descent constraint is active in the RTE LEGS page.
=====================================================

So there could also be a piece of a STAR (which was initially assigned to
another runway) still in the RTE page.
If that star was for rw13, and you've been cleared for 31, you can't make
that initial approach. Therefore the descent path is unachievable.

These are the options that spring to mind. If anyone would care to jump in
and correct me, please do. I've been spending too much time in the GA's
lately. :-)

HTH.

--

Marcel
(If you want to grow old as a pilot, you've got to know when to
push it, and when to back off. - Chuck Yeager)
Anonymous
February 23, 2005 3:14:01 PM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

Hi Tom,

Got him, mate!! :-))

Regards,
John Ward
"Tom Allensworth" <tom@REMOVETHISavsim.com> wrote in message
news:tNtSd.3199$Ba3.838@newsread2.news.atl.earthlink.net...
> you guys and gals are a much
> friendlier bunch!!! ;0))
>
> Hey... that wasn't very friendly... :) 
>
> --
> Best Regards,
>
> Tom Allensworth
> Publisher,
> AVSIM Online
> Flight Simulation's Premier Internet Resource!
> -------------------------------------
> http://www.avsim.com
> email: tom@avsim.com
> -------------------------------------
> See the rankings of your favorite Sim
> Web Sites:
> http://www.avsim.com/pages/rank_complete.html
> "IAIN SMITH" <iainsmith.rugby@btinternet.com> wrote in message
> news:cvdkg8$laf$1@hercules.btinternet.com...
> > Before boB says anything I *know* there's an Avsim forum for this but I
> > can never remember my password and, anyway, you guys and gals are a much
> > friendlier bunch!!! ;0))
> >
> > To those PMDG 737NG fliers amongst us - I programme a flight in the FMC
> > and everything appears fine. So how is it that every time after starting
> > its descent the overhead indicator "off scheduled descent" lights up and
> > closer to the destination the FMC reports "descent path unachievable"
when
> > it calculated the descent path in the first place! What is going on or
> > what am I doing wrong/not doing? Any suggestions would be appreciated.
> > :0))
> >
> > Iain
> >
>
>
Anonymous
February 23, 2005 4:05:05 PM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

Off-schedule descent comes on when you commence a descent before reaching
the cruise altitude set in the pressurisation section of the overhead panel
(bottom right). If you tie this in with your cruise altitude and stick to
it, you won't get the warning.

Or so it is in the real aircraft!

"IAIN SMITH" <iainsmith.rugby@btinternet.com> wrote in message
news:cvdkg8$laf$1@hercules.btinternet.com...
> Before boB says anything I *know* there's an Avsim forum for this but I
> can never remember my password and, anyway, you guys and gals are a much
> friendlier bunch!!! ;0))
>
> To those PMDG 737NG fliers amongst us - I programme a flight in the FMC
> and everything appears fine. So how is it that every time after starting
> its descent the overhead indicator "off scheduled descent" lights up and
> closer to the destination the FMC reports "descent path unachievable" when
> it calculated the descent path in the first place! What is going on or
> what am I doing wrong/not doing? Any suggestions would be appreciated.
> :0))
>
> Iain
>
Anonymous
February 23, 2005 6:52:55 PM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

"Bill Leaming" <n4gix@comcast.net> wrote in message
news:aqeo7yluhn0b$.17e906fnpwpw5$.dlg@40tude.net...
> On Mon, 21 Feb 2005 21:40:24 +0000 (UTC), IAIN SMITH wrote:
>
>> Before boB says anything I *know* there's an Avsim forum for this but I
>> can
>> never remember my password
>
> Why do you need to "remember your password?" Once you've logged in ONCE,
> you should be able to return without logging in again, provided you
> haven't
> disabled the cookie for avsim...

Surely once you sign out after visiting the site you have to login again? I
have to! And we are supposed to sign out on leaving are we not? :0))

Iain
Anonymous
February 23, 2005 6:52:56 PM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

On Wed, 23 Feb 2005 15:52:55 +0000 (UTC), IAIN SMITH wrote:
> Surely once you sign out after visiting the site you have to login again? I
> have to! And we are supposed to sign out on leaving are we not? :0))

No, there is no such requirement.

Bill
Anonymous
February 23, 2005 10:02:16 PM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

Ok, firstly the pressurisation thing is not related to the original
question, although if you do a flight and fail to reach the dialled altitude
it will cause a warning.

The real reason is as follows:

When in path descent and above the path, the FMC predictions show the
profile restrictions at the next waypoint cannot be achieved (LNAV remains
engaged, VNAV disengages). Displayed if the desired flight path angle to
meet the next constraint exceeds 7 degrees for aircraft operation when more
than 1000' above the airport speed restriction altitude, otherwise 6
degrees. To overcome this issue modify the restrictions, such as height or
speed at the next waypoint.

An extreme example is you cross waypoint 10 at 320kts and FL350. The FMC
then has an entry for waypoint 11 which is 1nm away and at FL250 and 320kts.
The aircraft simply couldn't make the waypoint 11 restiction with the wings
attached. Ok very extreme but hopefully it makes the point. As your route
still needs to pass waypoint 11 just delete the altitude constraint and
re-engage VNAV.

One thing I often do before I get to TOD (Top of descent) is change the DES
page speed to 280kts rather than the computed 310+. I do this well before
TOD so it can re-compute but it avoids these types of issues quite often. I
rareley get the problem however if I do I just use V/S to get back on the
profile indicator then hit VNAV again.

HTH

Regards

Geoff






"My T Sharp" <emailthis@myass.com> wrote in message
news:5c%Sd.3$nU6.1@newsfe4-gui.ntli.net...
> Off-schedule descent comes on when you commence a descent before reaching
> the cruise altitude set in the pressurisation section of the overhead
panel
> (bottom right). If you tie this in with your cruise altitude and stick to
> it, you won't get the warning.
>
> Or so it is in the real aircraft!
>
> "IAIN SMITH" <iainsmith.rugby@btinternet.com> wrote in message
> news:cvdkg8$laf$1@hercules.btinternet.com...
> > Before boB says anything I *know* there's an Avsim forum for this but I
> > can never remember my password and, anyway, you guys and gals are a much
> > friendlier bunch!!! ;0))
> >
> > To those PMDG 737NG fliers amongst us - I programme a flight in the FMC
> > and everything appears fine. So how is it that every time after starting
> > its descent the overhead indicator "off scheduled descent" lights up and
> > closer to the destination the FMC reports "descent path unachievable"
when
> > it calculated the descent path in the first place! What is going on or
> > what am I doing wrong/not doing? Any suggestions would be appreciated.
> > :0))
> >
> > Iain
> >
>
>
Anonymous
February 23, 2005 11:35:10 PM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

"GeoffC" <geoff_noise@hotmail.com> wrote in message
news:cvijvq$ihk$1$8302bc10@news.demon.co.uk...
<Snip>
> To overcome this issue modify the restrictions, such as height or
> speed at the next waypoint.
<Snip>

<Snip>
> One thing I often do before I get to TOD (Top of descent) is change the
> DES
> page speed to 280kts rather than the computed 310+. I do this well before
> TOD so it can re-compute but it avoids these types of issues quite often.
> I
> rareley get the problem however if I do I just use V/S to get back on the
> profile indicator then hit VNAV again.
<Snip>

Thanks Geoff, I'll give that a try. I assumed that the FMC would at the
outset look at the whole route and compute each waypoint
distance/height/speed. It seems from what you say that it does the whole
thing in approximate terms and then more accurately at each waypoint to the
next one. Correct?

Iain
Anonymous
February 23, 2005 11:38:51 PM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

"Bill Leaming" <n4gix@comcast.net> wrote in message
news:h7dlgx5351mn$.p66nvjmekojs.dlg@40tude.net...
> On Wed, 23 Feb 2005 15:52:55 +0000 (UTC), IAIN SMITH wrote:
>> Surely once you sign out after visiting the site you have to login again?
>> I
>> have to! And we are supposed to sign out on leaving are we not? :0))
>
> No, there is no such requirement.

OK Bill, I think I've got it straight now! I've just re-registered on the
forum and have a new password. I have seen where you can set it to remain
logged in when you leave the site. However, it seems this is overwritten
every 30 days when you need to log in again (or so it said on the site).
Anyway, I have made a careful note of my password so I should be ok.

Iain
Anonymous
February 24, 2005 1:44:47 AM

Archived from groups: alt.games.microsoft.flight-sim (More info?)

"My T Sharp" <emailthis@myass.com> wrote in message
news:5c%Sd.3$nU6.1@newsfe4-gui.ntli.net...
> Off-schedule descent comes on when you commence a descent before reaching
> the cruise altitude set in the pressurisation section of the overhead
> panel (bottom right). If you tie this in with your cruise altitude and
> stick to it, you won't get the warning.
>
> Or so it is in the real aircraft!

Yep! seems to be so with the PMDG as well. Thanks "My T Sharp"! :0))

Iain
!