Abstract: A helicopter weight measuring system for detecting the loaded weight of a helicopter operating under partial or full hover conditions while the wheels of the helicopter are contacting the ground includes means for sensing loading on the landing gear of the helicopter and means for determining the lift produced by a rotating wing of the helicopter. The sensed loading on the landing gear is added to the calculated lift to produce an indication of total helicopter loading.

Abstract: In order to reduce nuisance warnings and to increase the effectiveness of real warnings produced by a ground proximity warning system, the criteria for generating a warning is varied for certain airport areas to take into account the terrain in those areas. Along with position data, certain flight parameters such as heading, altitude, glideslope and localizer deviation are checked by the system in order to ensure that the aircraft is located in the desired warning modification area. In addition, the ground proximity warning system includes a mechanism for ensuring that the corrected barometric altitude of the aircraft is within acceptable limits.

Abstract: A dynamic low tire pressure detection system for detecting the presence of a low tire mounted on a structural member of an aircraft, such as a bogie beam or nose axle, includes a pair of inclinometers mounted on the structural member and adapted to sense the bend therein. The signals from the inclinometers are combined to generate signals representing the weight carried by the structural member. When the aircraft is moving, the weight signal is analyzed to determine whether particular frequency components are present therein. The amplitude of these frequency components are modified by a gain factor dependent upon a reference amplitude and are added to develop a tire pressure signal. The tire pressure signal is compared against a trip setting to determine whether the tire pressure is within acceptable limits. If the tire pressure is outside of the range of acceptable tire pressures, a signal is generated to warn of a potentially dangerous condition to the aircraft operating personnel.

Abstract: A weight and balance system which automatically compensates for loading errors while the aircraft is stationary. A weight signal is generated from the outputs of a pair of inclinometers mounted on adjacent opposite ends of a landing gear member which bends in response to aircraft weight. The weight signal generated just after no movement of the aircraft is detected is held in a latch. The held weight signal and a subsequently generated weight signal are combined to provide a signal representative of the difference therebetween. The difference signal is scaled by an error correction coefficient to provide a loading error compensation signal which is combined with the subsequently generated weight signal to provide a corrected weight signal. The system further includes means for performing reasonableness tests in response to the restoration of power to the system after power has been down.

Abstract: A static low tire pressure detection system for detecting the presence of a low tire mounted on a structural member of an aircraft, such as a bogie beam or nose axle, includes a pair of inclinometers mounted on the structural member and adapted to sense the bend therein. The signals from the inclinometers are stored in a memory once the aircraft is at rest on the ground to provide reference signals indicating the angle of the structural member with respect to an inertial reference and the weight carried thereby. The reference signals are compared against later-developed signals representing instantaneous angle and weight on the structural member to develop difference signals. The difference signals are used to generate an indication of tire pressurization, which is then checked to determine whether the tire pressurization is within acceptable limits.

Abstract: To increase the effectivity of warnings and to decrease nuisance warnings in a ground proximity warning system having several modes of operation, the switching from one mode to another is done as a function of time. In addition, in a ground proximity warning system where a warning signal is generated in accordance with a predetermined relationship between flight parameters, one or more of these parameters can be varied as a function of time in order to, for example, increase the altitude above ground as a function of time from take-off that a terrain clearance warning may be generated or to decrease as a function of time, the radio altitude below which a negative take-off after a climb warning may be generated.

Abstract: During a take-off or missed approach phase of operation the aircraft's maximum barometric altitude is retained in a memory element and compared to the aircraft's current altitude, and if the aircraft's current barometric altitude should be below the maximum altitude by a predetermined amount based on the aircraft's radio altitude, a voice warning is generated indicating that the aircraft is descending. Landing gear and flaps are monitored by the system and if the gear or flaps are down, an additional voice warning is generated indicating that the gear or flaps are down.

Abstract: A weight and balance system for an aircraft or the like which measures the bend in a structural member of the aircraft, such as a landing gear element or a wing or fuselage section, by use of inclinometers mounted to the member and each having a signal output representing the angle of the member with respect to a reference plane and then summing signal outputs from the incinometers to determine the angle of the bend which provides an indication of weight. In one example, the landing gear of the aircraft includes a member which bends in response to aircraft weight and a pair of inclinometers, in the form of servoed accelerometers, are mounted to the member adjacent opposite ends thereof and each provide a voltage output representing the angle of the member relative to the reference plane, and a summing device for summing said signal outputs as an indication of weight.

Abstract: In an aircraft excessive rate of descent warning system that utilizes barometric descent rate compared with aircraft altitude above ground to generate a warning, nuisance warnings at airports having terrain that slopes generally downwardly towards the runway can be substantially reduced by modifying either the descent rate signal or the altitude above ground signal as a function of radio altitude rate thereby having the effect of increasing the descent rate required to trigger a warning when the aircraft is descending essentially parallel to the ground.

Abstract: The warning system includes a function generator for generating a signal representative of a minimum altitude over terrain as a function of the aircraft's speed. This signal is combined with a signal representing the aircraft's actual altitude over the terrain and if the aircraft is below this minimum altitude a warning signal is generated. A circuit is included to inhibit the warning signal, and thereby nuisance warnings, when the aircraft overflys another aircraft. In addition, electronic circuitry is disclosed for implementing the invention that is compatible with at least two separate types of air data computers.