Alt Hold

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Petermuc3
Airman
Posts: 13
Joined: 22 Sep 2018, 04:49

Alt Hold

Post by Petermuc3 »

I am trying to adjust my altitude (being in Alt Hold mode) by using the vertical trim switch next to the A/P mode selector. But this does not work,
the aircraft is still holding the current altitude. Maybe I am doing something wrong here, but thought I followed the manual.
"The Vertical Trim switch may be used to adjust the
selected altitude up or down at a constant rate of 500 fpm
without disengaging the mode."

Peter

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Nick - A2A
A2A Captain
Posts: 13728
Joined: 06 Jun 2014, 13:06
Location: UK

Re: Alt Hold

Post by Nick - A2A »

Hello Peter,

Please bear in mind this function works via press and hold of the vertical trim rocker switch, not a momentary press.

Thanks,
Nick

alan CXA651
Senior Master Sergeant
Posts: 2438
Joined: 15 Mar 2016, 08:23

Re: Alt Hold

Post by alan CXA651 »

Hi.
If alt is showing on the autopilot , then you cannot change alt , first deselect alt then hit the up/dn trim on the left side of the autopilot , and once at the new alt reselect the alt , or on the alt preselect , dial in the alt you wish to goto , hit the arm , deselect the alt hold , then hit the up/dn button and once the preselected alt is achieved the alt hold will auto select on.
regards alan. 8)
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Nick - A2A
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Posts: 13728
Joined: 06 Jun 2014, 13:06
Location: UK

Re: Alt Hold

Post by Nick - A2A »

Actually this is incorrect Alan:
alan CXA651 wrote:If alt is showing on the autopilot , then you cannot change alt (...)
The vertical trim switch works in ALT HOLD mode as the OP states. However, as I clarified above, the rocker switch has to be pressed and held when using this function.

Thanks,
Nick

Petermuc3
Airman
Posts: 13
Joined: 22 Sep 2018, 04:49

Re: Alt Hold

Post by Petermuc3 »

Thanks Nick,
works like a charme.

Peter

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Paughco
Senior Master Sergeant
Posts: 2095
Joined: 30 Nov 2014, 12:27

Re: Alt Hold

Post by Paughco »

So based on reading all the comments above, and looking again through the POM, it appears that if you are flying IFR at 11,000 and ATC says "Bonanza 41 Golf, descend to 6,000," you reach out and press and hold the vertical trim rocker switch in the down position, and you get a constant 500 fpm descent rate. What happens when ATC comes back with "Bonanza 41 Golf, please expedite your descent."?

Let's assume we want to continue using the autopilot. One way to go would be to disengage the ALT hold, and press the vertical trim rocker switch until you get a 700 fpm descent, then reengage the ALT hold as you approach your assigned altitude. Or maybe press and hold the control wheel steering (CWS) button on the control wheel. Changing your altitude on the KAS 297 appears to just tell you when you approach or leave the selected altitude; it doesn't appear to command an altitude change.

One thing I notice is that the POH says the CWS button is "normally located on the left hand horn of the control wheel." Strange. My CWS button appears to be that little black button on the right hand horn of the control wheel.

Seeya
ATB
Last edited by Paughco on 25 Sep 2018, 11:07, edited 1 time in total.
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alan CXA651
Senior Master Sergeant
Posts: 2438
Joined: 15 Mar 2016, 08:23

Re: Alt Hold

Post by alan CXA651 »

Hi Paughco.
Do what i do when flying the conni and get asked that , (do you want me to go down or slow down i can not do both).
regards alan. 8) :lol:
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Paughco
Senior Master Sergeant
Posts: 2095
Joined: 30 Nov 2014, 12:27

Re: Alt Hold

Post by Paughco »

Looks like I need to test all this stuff out some more, perhaps on a flight from KAWO to KSZT.

Seeya
ATB
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some1 - A2A
A2A Lieutenant Colonel
Posts: 1828
Joined: 03 Aug 2008, 11:56

Re: Alt Hold

Post by some1 - A2A »

Paughco wrote:So based on reading all the comments above, and looking again through the POM, it appears that if you are flying IFR at 11,000 and ATC says "Bonanza 41 Golf, descend to 6,000," you reach out and press and hold the vertical trim rocker switch in the down position, and you get a constant 500 fpm descent rate. What happens when ATC comes back with "Bonanza 41 Golf, please expedite your descent."?

One thing I notice is that the POH says the CWS button is "normally located on the left hand horn of the control wheel." Strange. My CWS button appears to be that little black button on the right hand horn of the control wheel.

Seeya
ATB
The rocker switch in alt hold mode is only for short altitude adjustments, more for fine tuning than anything else. For any climb and descend that lasts longer than a few seconds, you want to disengage alt hold and adjust the pitch to desired climb/descend rate using either the rocker switch (which now controls pitch) or CWS button.

There is no standard CWS button location as it is not a factory option but an aftermarket installation. We put it on the right horn for better visibility, though in real aircraft I would probably install it on the left horn so I could use the switch and reach the engine controls at the same time.
Michael Krawczyk

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