Flight path calculator

Claim 1

A flight path calculator calibrated to display the descent path for a selected type of aircraft, comprising: a first member having a distance scale increasing linearly in a predetermined direction and calibrated in units of distance; a second member having an altitude scale increasing in said predetermined direction and calibrated in units of altitude, said altitude scale consisting of three portions: (a) a first portion having a range from zero to a predetermined deceleration altitude and calibrated such that equal lengths of said first portion and said distance scale correspond to units of descent and the distance flown by said aircraft during said descent, respectively, at the indicated air speed for flight of said aircraft below said deceleration altitude; (b) a second portion in which the altitude indicia is maintained at said deceleration altitude and having a length relative to said distance scale corresponding to the distance said aircraft would travel while decelerating from the indicated air speed for flight of said aircraft above said deceleration altitude to said indicated air speed below said deceleration altitude, one end of said second portion being coincident with the said deceleration altitude indicium of said first portion; and (c) a third portion having a range from said deceleration altitude to a selected maximum altitude and calibrated such that equal lengths of said third portion and said distance scales correspond to units of descent and the distance flown during that descent, respectively, at said speed above said deceleration altitude, said deceleration altitude indicium of said third portion being coincident with the other end of said second portion; and means for constraining said first and second members to move relative to each other while maintaining said distance and altitude scales juxtaposed so that the markings on one can be read off against the markings on the other.