Abstract: An aircraft navigation control system includes a flight management system control display unit (12), a navigation display unit (40), logic circuitry (60) and a cursor control input device (70). The flight management system control display unit (12) includes a keyboard (30) to allow desired route waypoint modification via keyboard entries. These entries appear on a display (20) which provides a text listing of the selected waypoints. The navigation display (40) produces a graphical depiction of the selected waypoints as provided on the flight management system control display unit (12). In addition, the user may modify or create a new desired route by movement of a cursor (4) on the navigation display (40) to thereby highlight and select various waypoints as depicted on the display (40). By use of this graphical interface via a cursor control device (70) and the cursor (74) on the navigation display (40), a user may create, by a connect the dot approach, a new desired navigation route.

Abstract: An improvement to an autopilot flight director system allows the flight crew to make a late runway change without disengaging the autopilot. The improved system allows a transition to a new runway assignment if radio altitude is greater than 1500 feet. Control logic determines whether or not localizer and/or glideslope have been captured and enters predetermined modes as a function thereof to effect a transition to the new approach while enabling instrument landing system retuning while maintaining autopilot engagement. Flight crew workload during approach is significantly reduced as a result of implementation of the improved system.

Abstract: A method wherein a quartz tube is charged with chunks of metallurgical grade silicon and/or a mixture of such chunks and high purity quartz sand, and impurities from a class including aluminum, boron, and the like, as well as certain transition metals including nickel, iron, manganese and the like. The tube is then evacuated and heated to a temperature within a range of 800.degree. C. to 1400.degree. C., whereupon a stream of gas comprising a reactant, such as silicon tetrafluoride, continuously is delivered at low pressures through the charge for causing a metathetical reaction of impurities of the silicon and the reactant to occur for forming a volatile halide and leaving a residue of silicon of an improved purity. Additionally, the reactant may include carbon monoxide gas, whereby impurites such as iron and nickel react therewith to form volatile carbonyls.