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PL & PE PLOTS

The Horizontal Protection Level (HPL) is the radius of a circle in the horizontal plane, with its centre being at the true position, which describes the region assured to contain the indicated horizontal position. The Vertical Protection Level (VPL) is the half length of a segment on the vertical axis with its centre being at the true position, which describes the region assured to contain the indicated vertical position.In other words, the HPL bounds the horizontal position error with a confidence level derived from the integrity risk requirement. Similarly, the VPL bounds the Vertical Position Error.The figures show the daily evolution of the HPL and the VPL using fault free techniques for their computation. The number of used satellites in the computation is also shown.