Altimeter mystery
Joined: Jan 2003
Aviation Qualifications: ATPL
Posts: 279
Likes: 17
From: Europe
I am not quite shure if that is what you mean, but a change in pressure during the 24h would change the altimeter readout if the altimeter setting is not adjusted accordingly.
So in your case a change of pressure of about 7 hPa would induce a difference of aproximately 200'.
So in your case a change of pressure of about 7 hPa would induce a difference of aproximately 200'.
Last edited by DBate; 15th August 2008 at 12:57.
Joined: Oct 2005
Posts: 3,218
Likes: 2
From: USA
Salmankaleem,
An altimeter is nothing more than a device for measuring air pressure. The altimeter has no idea how high it really is; it only knows about air pressure. It's designed on the premise that air pressure decreases at a known rate, with altitude. If the altimeter sits on the ground and air pressure changes as weather or a front moves through, the altimeter reading will change...because it's sensing air pressure.
A difference of a thousand feet is possible on an altimeter with the passage of a front, though it's seldom that great. Several hundred feet isn't at all uncommon. To correct the altimeter reading, check the local altimeter setting and put it in the altimeter window ("Kollsman window"), or simply adjust the altimeter until it indicates field elevation.
An altimeter is nothing more than a device for measuring air pressure. The altimeter has no idea how high it really is; it only knows about air pressure. It's designed on the premise that air pressure decreases at a known rate, with altitude. If the altimeter sits on the ground and air pressure changes as weather or a front moves through, the altimeter reading will change...because it's sensing air pressure.
A difference of a thousand feet is possible on an altimeter with the passage of a front, though it's seldom that great. Several hundred feet isn't at all uncommon. To correct the altimeter reading, check the local altimeter setting and put it in the altimeter window ("Kollsman window"), or simply adjust the altimeter until it indicates field elevation.
Joined: Feb 2000
Posts: 789
Likes: 0
From: UK
My microlight is stored in my garage and yes I could go out to it after setting the alt to 0 and find it reading 200ft the next day if we have a big pressure change
Joined: May 2001
Posts: 10,804
Likes: 1
A garage doors though are very common.
And alot more than 200ft can be the difference in a lot less than 24H.
I think my record was 600ft in the space of a bacon roll in SUM but it was blowing a gale 65 knts. Felt very sorry for the poor guys we had just taken up on a boat swap.
And alot more than 200ft can be the difference in a lot less than 24H.
I think my record was 600ft in the space of a bacon roll in SUM but it was blowing a gale 65 knts. Felt very sorry for the poor guys we had just taken up on a boat swap.
