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A few questions guys

PostPosted: Sun Sep 14, 2003 3:25 pm
by gilbates
Work with me here guys please , yes yes i should know the answers but ..... i dont ok

what does QNH stand for exactly

what does NOSIG mean

and when given Alt settings by ATC which are pretty important ( on-line that is ) my plane shows something like 29.?? mb or i think its millibars anyway but they give it to me differently , they give the other way .... er which evades me also , the name i mean

yes yes all pretty vague but ya get my drift , is there a simple mathematic  conversion so i can change my Altimeter and set the correct reading

Re: A few questions guys

PostPosted: Sun Sep 14, 2003 3:44 pm
by ozzy72
NOSIG-means No Significant Change in the weather.
QNF is mean sea level altimeter pressure setting.
Okay if you want to get pressure settings in millibars, you have to change one of the settings in options, I can't remember which one, but it'll stop giving it in millimeters or inches of mercury (I can't remember which as I haven't changed it for about a year ::)).

Ozzy ;)

Re: A few questions guys

PostPosted: Sun Sep 14, 2003 3:47 pm
by Nexus
QNH is the atmospheric pressure at nautical height, ie: Sea level

NOSIG: Should mean "No Significant change", and that term is used to describe the wheater conditions, I believe.

The 29.92 is NOT millibar. The term aviators would use is Inches of Mercury (inches HG)
That term is used in America. Here in Europe we have the Hecto Pascal (HPA)

Millibar is also used in aviation, but 1mb is 100 pascals.
So 1013 HPA is 1.013mb

Re: A few questions guys

PostPosted: Sun Sep 14, 2003 3:50 pm
by Nexus
Aww bugger...Ozzy shows who's the daddy on the forums, beat me by 3 mins!
;D

Re: A few questions guys

PostPosted: Sun Sep 14, 2003 4:04 pm
by ozzy72
I aim to be an annoying know-it-all Nexus ;) ;D ;D ;D

Re: A few questions guys

PostPosted: Sun Sep 14, 2003 4:06 pm
by gilbates
hahah Thanks guys , thats why i like it here , you always make me laugh ..... awww bugger indeed

thanks for the replys and i know its picky but QNH means Atmospheric pressure at nautical height then why the Q ? the big word begins with an A  ;D

and i`l have a look to see if i can change the pressure millibars and inches thingy

Very technical me with terminology aint i ;D ;D ;D

Re: A few questions guys

PostPosted: Sun Sep 14, 2003 4:11 pm
by Nexus
I aim to be an annoying know-it-all Nexus ;) ;D ;D ;D


Glad I'm not alone  ;D  ;D

Have a great one :)

Re: A few questions guys

PostPosted: Sun Sep 14, 2003 4:29 pm
by Nexus
[quote]hahah Thanks guys , thats why i like it here , you always make me laugh ..... awww bugger indeed

thanks for the replys and i know its picky but QNH means Atmospheric pressure at nautical height then why the Q ? the big word begins with an A

Re: A few questions guys

PostPosted: Sun Sep 14, 2003 7:31 pm
by zcottovision
If you're interested in learning how to read a METAR properly, I'd recommend visiting http://aviation.weathersa.co.za/codesexpl.htm ! They have pretty much everything you need to know about reading a proper METAR, and it really helps!

Re: A few questions guys

PostPosted: Sun Sep 14, 2003 8:06 pm
by OTTOL
QNH is Quasi-nonHydrostatic.  It is read in millibars, as opposed to Standard (US) which is expressed in Inches of Mercury. It's importance has to do with proper indication on your altimeter. Pressure constantly changes, and affects the altimeter indication. One worse case example would be, if you traveled from one airport to another, perhaps 100 miles away. If the temperature at your destination airport is much lower, your altimeter indication will indicate an altitude which is HIGHER than your ACTUAL altitude. ie: you may be at 50ft OR LESS! when your altimeter reads 1000ft. This would be an extreme example, but I think you can see the importance. Sometimes 50ft can  spell a LIFETIME! Especially in mountainous terrain. Try to find a thread titled "what does "29.92" mean", it answers all you want to know about the subject, and has some interesting dialogue! ;D
http://www.srh.noaa.gov/elp/wxcalc/alti ... ting.shtml