most probable position

most probable position

[′mōst ′präb·ə·bəl pə′zish·ən]

(navigation)

The computed position of an aircraft determined by comparing a dead-reckoning position and a loran position determined for the same period of time, in which relative weights are given to the estimated probable errors of each.

That position of a craft judged to be most accurate when an element of doubt exists as to the true position; it may be a fix, estimated position, dead-reckoning position, no-wind position, or some other position as determined from the squares of the estimated probable errors of each.

most probable position (MPP)

Area of uncertainty around the air plot position is 8 NM/h if TAS is up to 250 knots and 20 NM/h if TAS is greater than 250 knots. Aircraft's most probable position is within this circle.

50% area of probability is 1% along track and 3% across track of distance flown since resetting ground position indicator. Aircraft's most probable position will lie in this area.

The most accurate estimate of position where an element of doubt exists as to the true position. The accuracy of the MPP is greatly dependent on the accuracy of the involved position lines, as well as the time since the last fix. The MPP may be plotted from one or more position lines.