Altimeter mystery
 

can a simple altimeter keep changing its reading if the aircraft is parked in open for 24 hrs, lets say can a difference of 200 ft be induced

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'.

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, 7mb not that big really.

Nick.

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.

Perhaps you should keep the door closed then :ok:

A microlight with a door - that's not very common is it????

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.