Hi all,

I have a problem with the altitude hold and the glide-slope capture.
The altitude hold works well at cruise altitude.
But after the descent (using the AP and the trimwheels) to about 2000-3000 feet for final
approach and slowdown, ALTITUDE HOLD DOESN'T WORK any more.
I am forced to use the trimwheels again to hold the altitude.

Then I position GS Auto for interception of the ILS. Both amber lights go on (Loc and GS)
on the annuciator panel and the loc and glide indication is also present on the Hsi.
The light of the Localiser then turns green and the capture works well.

The light of the Glideslope turns then also green, but the plane dives below the glidepath
and the light goes amber again. GLIDESLOPE IS NOT CAPTURED!
I have to intervene manually again to complete the landing.
Fortunately manual flying is a pleasure with the 707!

I have made some research on this forum: several people signaled similar problems with the
glideslope but there was no real solution given, except from loading first the C172, what I do.

I know how to fly an ILS and intercept the glidepath always from below and at the right speed.
It happen's not at a specific airport, but everywhere.
I have tried everything now, it doesn't work!

What else could be the cause of this?


Guy

So we are at least two having this GLIDESLOPE problem.

To answer your second question:
in the VC you can raise or lower the seat by SHIFT BACKSPACE or SHIFT ENTER.
With Shift +/- you can zoom in and out .
With CTRL Backspace/ENter you can move the position backwards or forwards.
With all that and the help of the arrows (left,right, up, down) you can
choose exactly the position you like.

Guy

Guy, Markoz:

Thanks for the suggestions. I flew Boston to Detroit and came in RW21L doing 155-160knots. GS worked fine. Maybe I was under-speeding the final.

On the seat adjustment, I will have to try that and get back to you. Also, thanks for the eyepoint adjustment.

I love this plane more than the others CS put out (except maybe the 727)

Thanks for your answers!

@Mark : I use VOR/LOC and G/S Auto for Localiser/Glidepath intercept
       I have also tried the default CTRL-Z command to hold altitude. That moves the Alt-hold
       switch to the upper position. But the result is the same: no hold!

@Lou :  I use the upper position of the altitude hold/elev.disconnect switch to hold the
       altitude (the switch has three positions). ALTITUDE HOLD WORKS WELL ON CRUISE!
       I use the pitch wheels for climb/descent and have no problems with that.
       I have no problems with the view outside.
       I think I know how to fly an Ils (have read your tutorial also) and am always (almost) on speed.
       I use full flaps without rush and large power changes.

I have made two more (short) flights now, with always the same result.

After descent from cruise and slowdown ALTITUDe HOLD DOES NOT WORK any more.
I switch off altitude hold then and use the trimwheels to hold the altitude.
This works well without problems.
If then I switch on again ALtitude Hold (without touching anything else) the nose goes
immediatly down slowly and it begins to descend! That is not normal!
I have to switch off Alt Hold again and use the trimwheels again to hold the altitude.

Localiser Capture works well without problems. (light amber, then green)
GLIDESLOPE CAPTURE DOES NOT WORK for me.
The GS light is amber on the annunciator and then turns green also and the plane begins
to descend. All seems normal first, but then it descends too fast well below glideslope
and the light turns amber again.
Then I switch off the AP and land manually which is fortunately a pleasure with this plane!

Guy

@CaptainEd. Glad to hear things seem to be working better for you. Good luck on your Boston to London flight.

@Guy. If you can't get the Altitude Hold and Glide slope capture working correctly, there could be an installation problem. Run the installer again and select the Repair option when asked. If you are using Vista/Win7 run the installer as an administrator. If that fails to fix the problem, then maybe the installer is corrupt. Download it again by doing this:

Check-in to Your Profile > Select product > Extended Download Service > Get New Links

Install from the new installer and see if it works.

Mark

If you want to hold altitude (I think) you have to set it also on the Flight Director panel

giorgio nicola wrote on Jul 26^th, 2011 at 11:44am:

No !
On those old birds (707/727)  the Flight Director is an independant system and has NO link with the autopilot.
You may and, i think,  should use it, but you are not obliged to use it.
It simply moves the pitch and roll command bars on the HFD, that's all!
This facilitates your manual flying but there is no link with the AP.
On today's birds the Autopilot follows the FD's commands.

BTW the real cause of my problems (altitude hold and Glideslope capture) was the fact that I had introduced a parameter
"elevator_trim_effectiveness=0.250" in the flight_tuning section of the aircraft.cfg of the 707, as I had found the trim oversensitive in the beginning !
When I did a repair install, as Mark had suggested, the problems disappeared!
I understood only afterwards (by making some tests)  that it was because the repair had reset this parameter to 1.0 again (default) !

Altitude hold and glideslope capture work perfectly (with or without FD) !   
And I can also live with the trim (as it is)  now.

Guy

one question guys.....
why g/s is already green miles far from rwy?
on a modern bird it's become alive only few miles before, and u capture it   only when u are on course...here it greens many time before 
and, of course, it doesn't work