Answer about "def" indication in Sea Level Pressure

[Pilot-4ES]

I found a couple of folks who wondered about the "def" indication when setting Sea Level Pressure. "def" is 29.92 inches of Hg. That is what pilots call standard Sea Level Pressure. The corresponding standard temperature is 59 degrees F. Tempeature affects a barometric setting and your Suunto has a temperature compesnated circuit! When a pilot does not know the barometer setting or the altitude of a landing location, we set our altimeters to 29.95 ( there will be error in our altimeter reading of course) but it will be close enough until we can get an accurate altimeter (Sea Level Pressure) reading or an accuate indication of known altitude. By the way, if lfying above 18,000 feet, we set our altimeters to 29.95 until descent to landing -- at that time we will get an accurate altimeter setting from an airport. If you don't know your altitude or current Seal Level Pressure reading, setting your watch to "def" will give you a pretty close reading of altitude. The manual discusses barometer/temp relationships but does not give this detail I have written about.

	Suunto Visit SuuntoWatches.com to see Suunto's full line of wrist top computers and compasses.