A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Instrument Flight Rules
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

What caused the VSI and ALT bouce in the IMC?



 
 
Thread Tools Display Modes
  #1  
Old April 19th 04, 11:01 PM
Teacherjh
external usenet poster
 
Posts: n/a
Default


Because you can never know too much about your plane's systems, you engage
the alternate air one day while the static port is working fine and note the
offset. Now you are ready with a known correction, when the time comes that
the primary air is hosed. Is this a valid test?


Only if engaging the alternate cuts off the primary. Because in that case,
when you engage the alternate air, you now have the situation you tested
(alternate air ONLY). If, OTOH, the perversities in the design are that the
primary air is left connected, then you do not have a valid test. Consider the
following scenario: You've done the test, and find that there is a 75 foot
difference with alternate air.

Then one day you are flying in the soup, you see a saucer shaped apparition,
you are boarded by little green men who take the cowling off, reroute the
engine exhaust into the static port plumbing, phone home, and vanish. Before
looking for Area 54 in the AF/D, you notice the altimeter shows you
underground.

Ok, pull the alternate air. Now you're still underground, but with a 75 foot
difference. You're still hosed because the hosed primary air is still part of
the system.

So, the alternate air had better cut off the primary air!

If it does (as it should) then the test is valid and useful.

Jose


--
(for Email, make the obvious changes in my address)
  #2  
Old April 19th 04, 11:31 PM
David Brooks
external usenet poster
 
Posts: n/a
Default

"Teacherjh" wrote in message
...

Because you can never know too much about your plane's systems, you engage
the alternate air one day while the static port is working fine and note

the
offset. Now you are ready with a known correction, when the time comes

that
the primary air is hosed. Is this a valid test?


Only if engaging the alternate cuts off the primary....
(snip LGM scenario)


So, the alternate air had better cut off the primary air!

If it does (as it should) then the test is valid and useful.


Does it, in your spam can? In mine? I probably have to go home and study the
systems, but I admit I can't remember this detail in the POH. Or is there
maybe some regulation behind your use of "should"? Inquiring minds want to
know.

-- David Brooks


  #3  
Old April 20th 04, 12:47 AM
Ray Andraka
external usenet poster
 
Posts: n/a
Default

I know mine does not. It just opens the static line to the cockpit.

David Brooks wrote:



Does it, in your spam can? In mine? I probably have to go home and study the
systems, but I admit I can't remember this detail in the POH. Or is there
maybe some regulation behind your use of "should"? Inquiring minds want to
know.

-- David Brooks


--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759


  #4  
Old April 20th 04, 03:46 AM
Teacherjh
external usenet poster
 
Posts: n/a
Default

Does it [cut off the primary], in your spam can?

Dunno. Have to check. But it had better if it's to be of use.


Or is there
maybe some regulation behind your use of "should"?


No. I am not from the FAA, nor do I play one on TV.

Jose

--
(for Email, make the obvious changes in my address)
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 05:31 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 AviationBanter.
The comments are property of their posters.