A terrain awareness system and method which provides increased warning times to the pilot of an aircraft of a hazardous flight condition while minimizing nuisance warnings. An important aspect of the invention is that the terrain background information as well as the terrain advisory and warning indications may be displayed on a navigational or weather display, normally existing within an aircraft, which reduces the cost of the system and obviates the need for extensive modifications to existing displays, such as a navigational and weather radar type display.

Terrain awareness system

An aircraft terrain warning generator is provided having a terrain and obstacle warning envelope having a lower boundary formed according to the lesser of the current aircraft flight path angle and the obtainable climb gradient.

Aircraft terrain information system

A navigational system for surface vessels that provides warning of impending grounding occurrences. A data base of bottom contours and submerged obstructions is compared to various indicators of the surface vessel's position and motion to provide alerts and to display bottom hazards ahead of the vessel.

Method, apparatus, and computer program products for alerting surface vessels to hazardous conditions

A device for avoiding aircraft collisions with the ground determines the geographical location of the aircraft, and has a data base containing a description of safety altitudes for the geographical location. From the geographical location and the description of safety altitudes, the collision-avoidance device computes an air floor about the vertical of the aircraft. The altitude of the floor is greater than or equal to the safety altitudes about this vertical. In addition, the collision-avoidance device predicts the air position of the aircraft and compares this situation with the air floor. An alarm sounds when the aircraft passes beneath the floor.

Collision avoidance device for aircraft, especially for avoiding collisions with the ground

We consider numerical algorithms for on-board flight trajectory generation and optimization in three dimensional space. Our approach relies on graph search algorithms, which perform a global search over the set of feasible trajectories. We start by formulating a simplified kinematic model that is appropriate for General Aviation aircraft. The cost function to be optimized includes, the cost function to be optimized accounts for position-dependent criteria such as the flight altitude and terrain clearance. Additional “dynamic” components that involve the angular velocities are introduced to account for riding qualities and pilot workload. Using an approximate grid-based discretization scheme, we transform the continuous optimization problem into a search problem over a finite graph, and apply Dijkstra’s shortest-path algorithm to this problem. To reduce the computation time to acceptable levels, we introduce a novel state reduction technique that leads to sub-optimal search. Further speedup is achieved by heuristic search techniques and hierarchical methods. Performance of the proposed algorithms is evaluated for a trajectory optimization problem with terrain following over a 100 × 100 kilometer area. Our experiments demonstrate the potential of these algorithms, when combined, to provide an on-board solution to realistic flight trajectory generation problems. ∗Graduate student, Department of Electrical Engineering, Technion—Israel Institute of Technology, Haifa, Israel †Department of Aeronautical Engineering, Technion—Israel Institute of Technology, Haifa, Israel ‡Department of Electrical Engineering, Technion—Israel Institute of Technology, Haifa, Israel

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Fast Graph-Search Algorithms for General-Aviation Flight Trajectory Generation

The authors present a novel solution to the problem of providing aircrew with a timely warning of a dangerously close approach to the terrain. An overview of why such a capability is required, the benefits it is expected to provide, and specific requirements that it must fulfil is given. The ground proximity warning techniques which are currently available are reviewed, and the benefits and limitations of each technique are assessed. The GEC Avionics Ground and Obstacle Collision Avoidance Technique (GOCAT), which forms part of the Total Terrain Avionics system, is introduced. The particular advantages of the GOCAT approach, such as the use of a terrain database, are identified, and issues of parameter selection, search area definition, and system limitations are described. The results of a GOCAT simulation are presented to demonstrate the conditions under which a warning is required and generated. The characteristics of a practical implementation for both civil and military applications are discussed. >

C. Hewitt

Papers

A ground and obstacle collision avoidance technique (GOCAT)