Estimation of Geodetic Altitude from Barometric One with Actual Meteorological Aerodrome Report Data

Altitude is one of the most important parameters of each airspace user. The global air traffic system uses a barometrical altitude as a key parameter for airspace users leveling within an existing network of flight routes. However, barometric altitude represents airplane distance from international standard atmosphere isobar calculated by hypsometric formula with measured static pressure as an input. Current weather takes an action into the main parameters of the atmosphere that lead to significant barometrical altitude variation. However, weather impact is slow and does not provide a significant effect on the safety of aviation. Many on-board systems of airplane require geodetic altitude which fixes airplane in relation to the reference ellipsoid. In the paper, we propose to use actual weather data from meteorological aerodrome reports to estimate shift between barometrical and geodetic altitudes. An estimated shift of scales makes it possible to transform one altitude to another. Estimated geodetic altitude is important for trajectory analysis based on position reports transmitted under automatic dependent surveillance-broadcast. Most airplane position reports include only barometric altitude. Therefore, estimated geodetic altitude is useful in trajectory data processing provided by ground surveillance data processing unit.