A system for warning the pilot of a tactical aircraft in a tactical maneuver such as a dive of the point at which recovery must be immediately initiated to prevent the aircraft from descending below a minimum desired altitude monitors and the altitude, descent rate and pitch angle of the aircraft, and issues a voice warning when recovery must be initiated. The system also provides warnings of dangerous flight conditions during non-tactical or common route segments of a flight such as the take-off, landing and cruise segments of a flight. Circuitry responsive to the arming of the weapons of the aircraft enables the tactical warning portion of the system and disables certain functions of the non-tactical portion of the sysem that may cause false warnings to be genrated during tactical manuevers.

An M-sequence signal is generated in an M-sequence generation circuit, and the M-sequence signal, which is successively delayed by a column-electrode driving circuit or a row-electrode driving circuit, is applied to a column-electrode group or a row-electrode group. A correlator finds a correlation between the M-sequence signal and a detection signal that has been detected by amplifying electrostatically induced voltage that appeared in the detection electrode of an electronic pen so that a position specified by the electronic pen is detected by a detection circuit as a coordinate signal. Thus, it is possible to obtain a coordinate detection signal having a superior S/N ratio without reducing the coordinate detection speed, and consequently to carry out a coordinate detecting operation with high precision.

To provide a predictive emergency warning to the pilot of flight and terrain conditions which will result in a collision with the ground unless the pilot takes immediate action, without issuing excessive nuisance warnings, the system uses input parameters from other aircraft systems such as the radar altimeter. Inertial Navigation System, and Central Air Data Computer which are processed in an on-board computer to determine when a warning is required. A software program which is part of the warning system provides a logic link between the on-board aircraft parameters and the on-board voice command ("pull-up, pull-up"). The software program is readily adaptable to all aircraft applications with varying amounts of modification depending on specific mission requirements for which this protection is required. A feature is the use of a continuously computing predictive warning algorithm (based on classical flight dynamics equations) in combination with unique inhibit logic equations. Another feature is the introduction of "extended coverage" logic which permits the altitude dependent, time limited use of an alternate (other than radar) altitude reference signal when the radar altimeter is beyond limits.

A ground proximity warning system especially adapted for a tactical aircraft provides the pilot with a warning in the event that the closure rate is excessive for the altitude above ground at which the aircraft is flying. The descent rate of the aircraft is monitored and used to bias the closure rate warning signal to reduce nuisance warnings when the excessive closure rate is part of an intentional maneuver such as a dive during a tactical mission.

A system for warning the pilot of a tactical aircraft in a tactical maneuver such as a dive of the point at which recovery must be immediately initiated to prevent the aircraft from descending below a minimum desired altitude monitors the altitude, descent rate and pitch angle of the aircraft, and issues a voice warning when recovery must be initiated. The system also provides warnings of dangerous flight conditions during non-tactical or common route segments of a flight such as the take-off, landing and cruise segments of a flight. Circuitry responsive to the arming of the weapons of the aircraft enables the tactical warning portion of the system and disables certain functions of the non-tactical portion of the system that may cause false warnings to be generated during tactical maneuvers.