Barometric altimeter on 'future' Freerunner ?

[William Kenworthy]

On Sun, 2008-05-18 at 11:58 +0100, Al Johnson wrote:
> On Sunday 18 May 2008, adam at laurasteele.net wrote:
> > GPS does give relatively accurate altitude/speed but it does have
> > error and is nowhere near as accurate as a calibrate barometer (since
> > an aircraft altimeter is just a barometer with a different face).
> >
> > Assuming someone has a data plan you can get the barometric pressure
> > from a nearby airport (most have a weather station, all data is pooled
> > by the FAA online**). Wouldn't be sure about other countries but I bet
> > France/most sizable would have something similar. That or you could
> > assume the "standard" 29.92 in/Hg and 1000ft per 1 in/Hg.
> >
> > An even more desperate thing you could do is call 1800-WX-BRIEF and
> > ask what the baro is at a local airport.
> >
> > **They also maintain a very detailed list of all airports available as
> > an XLS file.
> 
> The airport information is available globally, and used by the kweather panel 
> applet. It looks like policy may vary by country for the size of airport to 
> be listed, but generally speaking it'll be listed if it handles international 
> flights. 
> 
> kweather lists temperature, air pressure, wind speed and direction, sunrise 
> and sunset, dewp oint and relative humidity. I haven't looked to see if 
> anything else is published, or what the update interval is.
> 

Its based on METAR information (http://en.wikipedia.org/wiki/METAR) -
basicly text based codes.

"A typical METAR report contains data for the temperature, dew point,
wind speed and direction, precipitation, cloud cover and heights,
visibility, and barometric pressure. A METAR report may also contain
information on precipitation amounts, lightning, and other information
that would be of interest to pilots or meteorologists such as Colour
States"

Just retrieve and process using perl or a lesser language.

BillK