The instrument used to measure an aircraft’s altitude is an altimeter. It measures altitude above mean sea level (MSL). An altimeter estimates these measurements using static air pressure. The altimeter estimates altitude based on changes in atmospheric air pressure.
The estimated measurement is based on a system that sets standard atmospheric pressure and temperature. Altimeters are set in accordance with the international standard atmosphere (ISA). These international standards are used to calibrate the plain altimeter so that the pilot can estimate elevation.
The standard measurement is a starting point for calculating altitude. Due to varying temperatures around the world an international standard is inaccurate for measuring altitude. Aircraft altimeters are equipped with an adjustable setting dial. Pilots can adjust their altimeters to local settings for atmospheric pressure so that estimating altitude is more accurate. Many airports worldwide broadcast local atmospheric settings across the airwaves so that pilots can adjust to the conditions.
It is important for skydiving adventures that the altimeter is set in accordance with local atmospheric pressure. Variations in pressure can affect the estimation of altitude so it is important that altimeters are set to local conditions. This will ensure the jump takes place at the correct altitude. With adventure skydiving free fall time is at a maximum. timing is crucial. Altitude measurements must be as accurate as possible for increased safety.
Skydivers are advised to set their personal altimeters to local atmospheric conditions at ground level. This will ensure they have an accurate estimate of altitude during the jump. Altimeter settings are also important when it comes to air traffic control. This is where an internationally standardized altimeter reading is useful. If some planes are flying with their settings adjusted to local conditions while others are using ISA there is a greater risk of mid air collision. Many pilots use local ISA when flying at low altitude and international ISA at higher altitudes.
Andrew Caxton is a journalist who has written more articles and newsletters on the subject for http://www.skydiving-parachuting-guide.com If you would like more information on this topic please checkout his skydiving website at altimeter watches