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DavyC

Altitude Hold

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Hi

 

I am learning at the moment so I have probably missed something so bear with me.

 

This has happened on a few flights but not all.

 

The auto pilot holds the altitude on the local barometer setting and not standard.

 

Example - I take off from KJFK where barometer setting is 3021, at FL180 I select standard and check setting at 2992.  I have FL310 set in FMC and autopilot.  The aircraft levels off at 30720, the purple dot is at 31000.  If I press B which changes barometer back to 3021 the altitude changes to reflect the aircraft at FL310.

 

I am sure I am missing something but what??

 

Thanks for any help

 

PMDG MD11 F (Only downloaded last week so I assume most up to date)

FSX SP2

Windows 7 (64bit)

 

Davy C

David Campbell

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I think you are reading the barometer switch incorrectly.

 

If you are above 18,000 feet and you press "B", the barometer of any aircraft will change to 29.92 (at least in FS9 it does)  Can you post a screenshot if you are sure you are operating it correctly.

 

Actually, whether you have the baro set to 29.92, or 30.21 , the aircraft should still level off at an indicated 31,000 feet

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Hi
 
See the attached

 

if I change to 3021 the indicator shows the aircraft is at FL310

 

DavyC

David Campbell

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Hi

 

If it helps when I did the step climb to FL350 all was correct as per 2992 setting

 

Davy C

David Campbell

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I have not seen this behaviour on my MD-11, I am using FS9.

 

What happens if you pull the ALT button or dial a VS of say 300, will it climb to 31,000 ?

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This is very strange... what was the outside air temperature at the time? Which weather program do you use?

 

Best regards,

Robin.

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You have to change the altimeter to 29.92 PRIOR TO altitude capture, otherwise it will ignore the change in the altimeter setting.  Once it captures the altitude, it follows that pressure level regardless of what the altimeter is set to.

 

I've never seen this behavior, so it's likely that you're just not doing something properly.  When you're setting standard at FL180, are you pulling the barometer setting button (shown as "PULL-STD"), or doing something else?

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Hmm - I'm sure I have seen it chase the altimeter on pressure changes, whether pilot or weather induced...

 

Best regards,

Robin.

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Folks

 

Thanks - it has not happened since.  I cannot recall but I may have missed the baro change at FL180 and changed after reaching the set altitude.

 

Appreciate the help

 

Davy C

David Campbell

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