yeah you're right ... sorry, I didn't read your post closely enough. I was
thinking just getting the readings from a weather station.
-- Canuck -------------------------------------------- Y2K, 4.7L, 2wd, 5spd, The Ultimate K&N HomeBrew, Flowmaster CatBack, Home Ported TB, Electric fan conversion, 180 therm., Redline synth., IAT adjuster, HO Cams, HO Intake waitng for install http://www.twistedbits.net/WWWProfile/dakota/Vyikam1jjgNN6<jon@dakota-truck.net> wrote in message news:ant82t$mn8$1@bent.twistedbits.net... > > "Canucker Trucker" <flamindakman@yahoo.co.uk> wrote: > > : one major problem with using barometric air pressure readings is that they > : are 'corrected' for altitude ... i.e.my barometer here reads 1.0 atm, but > : its really .95 atm absolute pressure (1.0 atm would be at sea level) ... > : it's really messed up but the reason they do that is so weather guys don't > : get confused. Best thing would be if the track you were at has an absolute > : pressure gauge. That's the key .. it has to be absolute without any > : altitude correction. > > > Canuck, > > I'm not sure what you mean. Are you referring to getting the readings > from a TV or radio weather report? I just read the number off my > el-cheapo barometer, which has no idea what altitude it is at. This is > why aircraft altimeters have an adjustment dial. When you put the plane > away after flying it and come back the next day, chances are extremely > high that the needle isn't reading the correct altitude; I have seen > differences of hundreds of feet when the plane has done nothing but sit > in the hangar. One of the first things a pilot will do during the > preflight or cockpit checklist is to reset his altimeter to field > elevation, because even an expensive aircraft altimeter really has no > idea what its true elevation is - its only a barometer which needs to > be corrected to some known quantity before it is accurate. In fact, > on a cross country flight, pilots will get pressure readings from > ground stations which they dial into their altimeters to keep them > accurate as they fly through different weather systems. > > > -- > > -Jon- > > .---- Jon Steiger ------ jon@dakota-truck.net or jon@jonsteiger.com -----. > | I'm the: AOPA, DoD, EAA, NMA, NRA, SPA, USUA. Rec & UL Pilot - SEL | > | '70 Barracuda, '92 Ram 4x4, '96 Dakota, '96 Intruder 1400, '96 FireFly | > `----------------------------------------- http://www.jonsteiger.com ----'
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