A manually operable calculator for optimizing aircraft fuel consumption during descent from an actual altitude to a target altitude/distance. Altitude and distance scales are provided which are alignable to determine an uncorrected fuel efficient distance to commence a descent from a given altitude to a target location, with separate scales being provided for different airspeeds. Wind and weight correction scales are also provided which give a distance correction based upon the aircraft's weight, prevailing wind conditions, and the difference between beginning and target altitudes. In the preferred embodiment a plurality of altitude scales are employed, each scale having thereon an altitude display which is proportioned in accordance with a respective air speed and given in terms of mach speed for altitudes above a mach speed/I.A.S. transition point, and in terms of I.A.S. below that point. In this embodiment a single, linear distance scale is employed.

A device utilizing three discs, which are rotatably positionable relative to each other, is provided for computing aerial navigation wind correction angle and ground speed correction for various combinations of aircraft True Course, Wind Direction, Wind Velocity, and True Air Speed. The first disc, which for most effective utilization of the device is referenced to the longitudinal axis of an aircraft outline, has a first series of informational whole number scales running circularly therearound indicating wind correction angles for various wind velocities, and a second circularly arranged series of whole number scales indicating ground speed corrections for various wind velocities. The second of these discs provides a compass rose around its circumference which is positioned in accordance with the aircraft true course set at the longitudinal axis of the aircraft outline of the first disc, and upon which the third disc is positioned in accordance with the wind direction. The third disc, which overlies the second disc, has windows which overlie each of the two numbered scales of the first disc respectively and enable a read out of the precomputed whole number information.

A system and method for issuing an aircraft drift advisory. In one embodiment, the system includes a head or eye tracker to monitor the rotational position of the pilot's line of sight with respect to the aircraft axis. The pilot's line of sight is compared to the direction of the aircraft. If the absolute value of the difference is greater than or equal to a predetermined angle, corresponding to the foveal cone of vision, the incremental aircraft drift distance is computed and used to update the cumulative aircraft drift distance. The cumulative aircraft drift distance is compared to the predetermined advisory criterion, which may be a constant, a uniform function of altitude or a function of altitude that is tied to a digital terrain map. When the cumulative aircraft drift distance equals or exceeds the advisory criterion, the pilot is given a drift advisory that the aircraft has drifted so as to prompt the pilot to adjust his line of sight to the direction of the drift. If the cumulative drift distance is less than the advisory criterion, the drift distance calculation is updated. In alternative embodiments, the drift distance is directly measured, and the time during which the drift distance equals or exceeds a threshold drift distance is compared to a criterion time to determine whether to issue the advisory. The system is designed to prevent a hovering aircraft from slowly drifting into contact with objects because the pilot is unaware of the drift for any reason.

The invention provides a method and device for determining the heading with wind (or with current) of an air (or sea-going) vehicle. The device of the invention comprises a support element with two coaxial compass cards, one of which is assigned to the heading without wind and the other serves as indication of the heading with wind, as well as a plurality of rings which may be mounted for rotation coaxially with said compass cards and in the coronal space therebetween. Each of the rings corresponds to a particular situation of the aircraft determined by a wind speed/aircraft speed ratio and has a pointer intended to be oriented along the wind bearing. A series of lines ensures the correspondence between the compass cards.

A device for computing the heading of an airplane in the outbound leg of a holding pattern, and the bearing to a VOR or NDB station at which the airplane should begin turning inbound at the end of the outbound leg, given the bearing of the outbound leg, the speed and bearing of the wind, and the true airspeed of the plane, but without requiring the user to keep track of the time. In a first preferred embodiment, the invention comprises a slide rule with upper, middle and lower disks attached at their centers by a pivot, and a straight rule movably retained in a groove in an upper disk. There is a logarithmic scale for true airspeed on the straight rule, and a parallel and adjacent logarithmic scale for wind speed on the upper disk. The lower and middle disks each have degree markings, and the middle disk also has figures for heading and bearing corrections, to which arrows on the straight rule point. In a second preferred embodiment, the invention comprises a digital electronic device programmed to make equivalent computations. The user is prompted to enter the given values. Heading and bearing corrections are retrieved from tables stored in memory, and used to compute the proper heading during the outbound leg and the bearing to the station at which to turn.