ALT HOLD for SP77

Find out more before you buy, or chat to other 737 pilots!
(No support requests please)
Locked
QF188
Posts: 3
Joined: Wed Oct 22, 2014 5:30 pm
ALT HOLD for SP77

Post by QF188 » Sat Sep 10, 2016 9:22 pm

Hi,

I try to use the autopilot of SP77 to hold altitude but I am not able to turn the knob to ALT HOLD position. The plane will keep on climbing. I set a desire altitude and when the plane approached that altitude I flip the ELEV Switch to UP position then right click it, it will spring back to OFF position right the way. I have no problem to left click it to the TURB position. Would anyone let me know the proper step to activate it?

Thank you.

Jay

N4GIX
Posts: 1023
Joined: Mon Sep 06, 2010 3:47 pm
Re: ALT HOLD for SP77

Post by N4GIX » Sun Sep 11, 2016 1:04 am

Why are you "right clicking" on the ELEV lever? That is used to turn it off!

QF188
Posts: 3
Joined: Wed Oct 22, 2014 5:30 pm
Re: ALT HOLD for SP77

Post by QF188 » Sun Sep 11, 2016 6:45 am

Hi Bill,

I am sorry I did not express clearly. I want to keep the plane at a preset altitude eg. FL310. When the plane was climbing, I flip the ELEV Switch up. When It was approaching 31000 feet, I tried to click the knob (TURB, OFF, ALT HOLD) from OFF position to the ALT HOLD position. That's why I right click the knob (not the ELEV Switch). However, the knob just sprung back to OFF position. Have I missed any procedure?

Thank you.

Jay

N4GIX
Posts: 1023
Joined: Mon Sep 06, 2010 3:47 pm
Re: ALT HOLD for SP77

Post by N4GIX » Sun Sep 11, 2016 3:47 pm

No, but you do have a fundamental misunderstanding of the SP-77 autopilot's capabilities and limitations. There is little to no "automation" in this primitive autopilot. The most advanced "feature" is the Control Wheel Steering (CWS), which on the whole works really well.

The altitude selector is used only as a audio/visual guide to your target altitude. It will trigger an visual/audible alert when you are within +/- 1000' of your desired altitude. It is up to you - the pilot - to level off and trim for neutral pitch before activating the ALT HLD function.

The reason the "manual" for the SP-77 is so short. There's really not too much to describe! :lol:

See: SP-77 Autopilot.pdf in the ..\Manuals folder.
ALT HOLD - autopilot will hold the current altitude. When higher forces on the yoke are
detected the switch will return to the OFF position
The reason the switch is returning to the OFF position is because you haven't trimmed for neutral forces on the yoke first.

This autopilot was designed to "assist" the pilots, not replace them... ;)

QF188
Posts: 3
Joined: Wed Oct 22, 2014 5:30 pm
Re: ALT HOLD for SP77

Post by QF188 » Sun Sep 11, 2016 9:03 pm

Hi Bill,

Thank you very much for the explanation. Very appreciate that. I picked My knowledge on flying piece by piece by reading flightsim manuals and forum. Thisgis a great help to me.

Cheers!

Jay


Locked

Return to “Boeing 737-200 General Forum”