Variable enhanced ground proximity warning system look-ahead offset and sub-offset The present invention includes a system, method and computer program product for reducing nuisance warnings during low altitude flight conditions and in the presence of low position uncertainty. The system includes a first component that determines whether the aircraft is in a low altitude flight condition and a second component that determines the position, positional uncertainty, and the heading. The system also includes a third component that attenuates and refines the look-ahead envelope in accord with the determined condition of flight and positional uncertainty. Flight guidance system providing perspective flight guidance symbology A flight guidance system providing perspective flight guidance symbology using positioning and terrain information provides increased pilot situational awareness of an aircraft. The guidance system uses a positioning system and a detailed mapping system to provide a perspective display for use in an aircraft. A Perspective Flight Guidance (PFG) symbology set is thereby displayed on a pilot display. The PFG symbology set includes broken line symbols representing an open tunnel and providing flow field data, a half-bracket symbol to indicate that the aircraft is no longer in the open tunnel represented by the broken line symbols and a quickened flight path vector (QFPV) symbol to provide the pilot with predictive flight path information. Apparatus for indicating air traffic and terrain collision threat to an aircraft Includes means for monitoring the position and behavior of air traffic in the vicinity of the aircraft and generating a warning or avoidance signal for air traffic predicted to be on a collision course. The apparatus also includes means for monitoring the position and behavior of the aircraft relative to terrain in the vicinity of the aircraft flight path to generate a warning or avoidance signal for terrain features predicted to provide a collision threat. Means are provided for receiving the traffic warning signals and terrain warning signals comparing the signals and generating a combined warning or advisory signal which indicates an action for the aircraft which avoids both air traffic and terrain collisions. Embedded terrain awareness warning system for aircraft An embedded terrain awareness warning system for aircraft being flown by a pilot includes a signal processing component, a protection component and a pilot vehicle interface. A method for providing an embedded terrain awareness warning system for aircraft being flown by a pilot includes providing a signal processing component, a protection component and a pilot vehicle interface. The signal processing component communicates with three-dimensional digital terrain elevation data and is able to take input data from aircraft sensors, aircraft computers or navigation systems and determine aircraft position and velocity. The protection component is in communication with the signal processing unit such that the protection component is able to determine if a potential controlled flight into terrain exists and is able to predict a recovery flight path to avoid terrain. The pilot vehicle interface communicates with the protection component such that the pilot vehicle interface can issue a warning to the pilot of the aircraft of impending flight into terrain, and issue a directive solution to prevent the impending flight into terrain. Premature descent into terrain visual awareness enhancement to EGPWS In order to provide the pilots with a display or a map of the terrain below the aircraft, a display is generated on a cockpit display, such as a weather radar, of the contours of the terrain below the aircraft. The terrain contour display is generated from aircraft position information, a terrain data base, and a terrain awareness envelope defined by awareness boundaries. Terrain contours are depicted with the highest terrain within the envelope colored red, high intermediate terrain contours in yellow with varying dot densities, low intermediate terrain contours in green with varying dot densities, and the lowest terrain in black. The green contours can be overwritten with a low density yellow based on a pre-caution envelope which extends certain of the awareness boundaries to provide notice to a pilot of upcoming cautions. Positioning and ground proximity warning method and system thereof for vehicle A positioning and ground proximity warning method for vehicle includes the steps of outputting global positioning system signals to an integrated positioning/ground proximity warning system processor; outputting an inertial navigation solution to an integrated positioning/ground proximity warning processor; measuring air pressure, and computing barometric measurements which is output to the integrated positioning/ground proximity warning processor; measuring time delay between transmission and reception a radio signal from a terrain surface, and computing radio altitude measurement which is output to the integrated positioning/ground proximity warning processor; accessing a terrain database for obtaining current vehicle position and surrounding terrain height data which is output to the integrated positioning/ground proximity warning processor; and receiving the position, velocity and time information or said pseudorange and delta range measurements of said global positioning system, the inertial navigation solution, the radio altitude measurement, the radio altitude measurement, and the current vehicle position and surrounding terrain height data, and computing optimal positioning solution data and optimal ground proximity warning solution data. Integrated horizontal and profile terrain display format for situational awareness A visual display format for a terrain situational awareness system comprising a horizontal terrain elevation view and a profile terrain elevation view of potential terrain hazards integrated onto a single display. Adaptive ground collision avoidance system A ground collision avoidance system that exhibits improved accuracy and performance by integrating with all other aircraft systems including guidance systems, navigation systems, digital terrain elevation databases, mission computers, and radar altimeters. The ground collision avoidance system fully utilizes active onboard sensors in combination with the knowledge of terrain and obstacle data contained in databases. Furthermore, the ground collision avoidance system provides a multiple processing path to determine numerous predicted flight paths based on a number of reasonable assumptions regarding the aircraft flight during a predetermined amount of time. By using predictive flight path schemes a realistic estimate of the predicted flight path envelope can be determined and then this information can be used in conjunction with accurate terrain elevation databases to determine whether a ground collision condition exists. On the basis of these calculations, appropriate warnings can be provided to the air crew as well as suggested maneuvers to avoid ground collision. Method and device for supplying information, an alert or alarm for an aircraft in proximity to the ground Information, an alert or an alarm is supplied to an aircraft in proximity to the ground. A grid of geographic coordinates is established, each mesh of which exhibits a defined relief. The trajectory of the aircraft is predicted over a predetermined time interval. An intersection, if any, between the predicted trajectory and the relief of at least one of the meshes is determined. An alert or alarm is activated in the case of such an intersection. The alert or alarm is inhibited when the aircraft is in landing configuration or when the runway is detected and a series of conditions relating to landing are fulfilled. Collision avoidance device with reduced energy balance for aircraft, notably for avoiding collisions with the ground Disclosed is a collision avoidance device with reduced energy balance for aircraft, in particular for avoiding collision with the ground. This device comprises means for the geographical localization of the aircraft, a database containing a description of safety altitudes, means for the construction of an air floor about the vertical passing through the aircraft, the altitude of the floor being greater than or equal to the safety altitudes about this vertical, means for predicting the air position of the aircraft, means to compare this position with the air floor, means for the computation of avoidance paths and means to determine the energy balance of each of the computed paths. Application to equipment for aircraft, notably for civilian airliners. Ground collision avoidance system A method and system for avoiding ground collision through pilot warning messages which is implemented in aircraft having a plurality of sensors, onboard inertial navigation units, and altimeters for measuring aircraft performance or flight characteristics. Data is collected through a digital interface unit from data buses connected to these sources, transferred to one or more storage locations and a data validation unit for determining the validity of current altitude data. A series of data processing elements use the aircraft data to extrapolate an aircraft altitude path forward during a predetermined period of time as a function of the aircraft flight data. The extrapolated altitutde allows extrapolation of an aircraft flight path as a function of predicted terrain variations and changes in altitude in response to recovery from various aircraft maneuvers such as rolling, banking, diving, climbing, or accelerating. The extrapolated altitude, or changes in altitude, is compared to one or more predetermined safety limits, and one or more warning messages are provided if the extrapolated altitude is lower than an appropriate limit. System for alerting a pilot of a dangerous flight profile during low level maneuvering A system that warns the pilot of an aircraft performing low level maneuvers of a dangerous flight profile monitors the altitude of the aircraft above ground, and provides a first specific warning to the pilot if the altitude of the aircraft drops below a predetermined minimum altitude above ground. The system further monitors the roll angle and descent rate of the aircraft to provide a second specific warning if the descent rate of the aircraft exceeds a predetermined rate determined by the roll angle of the aircraft if the aircraft is below a second predetermined altitude above ground. Low altitude warning system for aircraft 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. Ground proximity warning system terrain classification system An aircraft ground proximity warning system is disclosed having an inadequate terrain clearance warning mode, wherein the criteria required to generate the warning is modified when the aircraft is flying over undulating or mountainous terrain. The system is responsive to signals representative of the radio altitude, the barometric altitude, the speed of the aircraft, the flap position and the landing gear position to provide warnings when the aircraft is operating below a predetermined altitude with either or both of the landing gear of the flaps not in a landing configuration. The warning system also provides a warning when the aircraft is traveling above a predetermined speed and below a predetermined altitude irrespective of the configuration of the landing gear or the flaps. Also disclosed is logic circuitry for detecting that the aircraft is flying over undulating or mountainous terrain and modifying the warning envelope during such condition to provide longer warning times. Terrain advisory system A terrain advisory system utilizes stored data representative of terrain and other obstacles in predetermined geographical areas of interest to provide advisory warnings of the proximity of terrain, obstacles and restricted areas as they are approached. When used in a vehicle such as an aircraft, the system monitors the position, altitude, ground speed, ground track and the vertical speed of the vehicle and provides advisory indications of the position and path of travel of the vehicle with respect to obstacles and terrain. Such advisory indications may take the form of voice warnings describing the nature and position of any obstacles, or a visual display showing the position of the obstacles and terrain with respect to the vehicle. Method and apparatus for controlling altitude The invention provides a vertical velocity signal and an integration signal, respectively, of two detected ambient conditions. The signals are summed, in a selectable ratio, and compared with a predetermined altitude set point. When there is a difference between the summed outputs and the altitude set point, an altitude control signal is provided to control a vertical propulsion system of an object whose altitude is to be maintained above a terrain. Minimum safe altitude monitoring, indication and warning system A geographically referenced minimum safe altitude monitoring, indication and warning system involving use of a navigation computer in conjunction with a memory device storing predetermined minimum safe altitude data as a function of geographic location. The stored data takes into account both natural terrain and man made flight hazards in a mosaic of geographic grid sections covering the navigational territory of interest, and it either arbitrarily assumes in such data "worst case" flight conditions, or one or more actual current conditions of vehicle course, velocity and altitude change rate in providing the system output whether in an airplane, submarine or other vehicle so as to indicate to the pilot or warn the pilot of existing minimum safe altitude or imminent approach to an unsafe altitude. Vertical path control for aircraft area navigation system In the vertical path control of an area navigation system when the aircraft ascends or descends to a waypoint with an "at-or-above" or "at-or-below" altitude requirement, vertical steering is effected at a constant airspeed with regard to a reference airspeed. An alert device is included to provide a warning to the pilot when the aircraft flight path angle is less than the straight line flight path angle to the waypoint for "at-or-above" waypoints or when the flight path angle of the aircraft is greater than the straight line flight path angle to the waypoint for waypoints with an "at-or-below" altitude requirement. Altitude error is displayed on a vertical deviation indicator of an aircraft flight instrument in accordance with the difference between the actual aircraft altitude and the altitude of the next waypoint having a firm altitude requirement. When the aircraft ascends or descends to a waypoint through the pressure-barometric altitude transition, flight path angles are computed and utilized as the vertical steering reference to avoid a steering discontinuity at the transition altitude. When the aircraft is on a descent path to a waypoint and an airspeed reduction is required, vertical angles are computed and utilized for generating the vertical steering signal whereby a speed reduction transition zone is included in the flight path to effect the speed reduction and make good the desired waypoint altitude.