| 摘要 |
A system for determining an instrument approach procedure for an aircraft comprises a database system containing terrain data and obstacle data, an input device onboard the aircraft for selecting a target position, a display device onboard the aircraft for displaying information to the pilot, and a processor onboard the aircraft. The processor determines, on the basis of the selected target position,a final approach path segment and a missed approach path segment. The final approach path segment begins at a final approach waypoint and ends at a missed approach point for deciding whether the aircraft may continue to a landing position on the ground or a missed approach procedure is started. The missed approach path segment begins at the missed approach point and ends at a higher altitude. A memory contains obstacle clearance surface data, on the basis of which, for each of the final approach path segment and the missed approach path segment, an obstacle clearance surface is defined that extends at a pre-determined orientation and at a pre-determined distance below said path segment. The processor determines an obstacle clearance altitude (OCA) for the instrument approach procedure as the lowest altitude at which any obstacle identified by the terrain data and obstacle data in the database system does not penetrate the obstacle clearance surfaces in the final approach path segment and the missed approach path segment. The system is configured to display the obstacle clearance altitude (OCA) on the display device. |
