Talk:Altimeter

message: 74.140.133.110 (talk) 02:14, 7 May 2008 (UTC)

message: I brought in the altimetry/bathymetry reference because it is a prime in-reference for altimetry, which is referred here. Feel free to rearrange as you see fit.--Natcase 03:17, 17 November 2006 (UTC)
thread_title: Untitled

message: Does an altimeter ever give false readings?
If it is only a special kind of barometer, is it ever resynchronized in the middle of a flight?   I am assuming that altimeters are initialized to a particular known state, usually at the time of takeoff.   If the barometer is electronic in nature, would a power failure cause it to resynchronize to a patently false state, even in midflight?   If lightning strikes a plane, how can you tell if the altimeter went through a reset sequence?  —Preceding unsigned comment added by 216.99.219.134 (talk) 19:36, 20 August 2009 (UTC)
thread_title:  False readings? 

message: The article didn't give any pictures depicting how to read an altimeter. This might get confusing.  —Preceding unsigned comment added by 64.219.120.5 (talk) 15:36, 23 August 2009 (UTC)
thread_title:  How to read? 

message: I think this opening sentence needs to be changed, because it is not quite accurate:
::"An altimeter is an instrument used to measure the altitude of an object above a fixed level."
Typical altimeters in aircraft, measure to MSL (Mean Sea Level), so it is a misnomer to say "above a fixed level." That is because MSL is not a "fixed level."  
"Mean sea level does not remain constant over the surface of the entire earth. Mean sea level at the Pacific end of the Panama Canal stands 20 cm higher than at the Atlantic end." here
My suggestion, then, is that the sentence be changed to read thus:
::"An altimeter is an instrument used to measure the altitude of an object above Mean Sea Level."  
Will appreciate further comments from other editors. 66.81.53.160 (talk) 11:26, 25 October 2011 (UTC)
replies: text: Sounds like a reasonable argument, but it's original research until you find a ref to support this definition.Socrates2008 (Talk) 12:17, 25 October 2011 (UTC)
thread_title:  Opening sentence 

message: The section on altimeters in aircraft contains the statement "An altimeter cannot, however, be adjusted for variations in air temperature".  Years ago an article in Summit Magazine (a climbing journal) carried an article on temperature correction.  Some factoids I recall: the scale on an altimeter assumes an FAA standard adiabatic lapse rate, or change in pressure with altitude.  It assumes a specific Tsea level.  If the actual Tsea level is known, then (to the extent that an adiabat is appropriate) you can indeed correct for temperature.  In effect, you have to correct for the fact that a column of air, say 300m high, weighs less when warm than when cold.  As you ascend, the error is in delta-H; you can't fix it by using a single known elevation.  A correction would no doubt be difficult for a mechanical altimeter, but surely it would be a piece of cake for a 21st century microchip?  Is it done?  Captain Puget (talk) 05:25, 30 November 2012 (UTC)
replies: text: In Pilot School, the saying is "From High to Low or Hot to Cold, look out below."   Meaning if moving from a high temperature area to a lower temperature, the altimeter will indicate a higher altitude than the plane is actually at.   The same happens if flying into a low pressure area.  There is no automatic correction, but a rule of thumb is 100ft per 10 degrees of temperature change. 8r455 (talk) 02:35, 5 February 2015 (UTC)
thread_title:  Temperature Correction