Navigation of aircraft by correlation

In a method of navigation and aerial guidance under utilization of elevational data correlation, wherein a correlator compares terrain specific elevational reference data, with actually acquired and processed altitude data, the improvement comprising:

• using a millimeter wave sensor operating in the atmospheric window of about 94 gigahertz for acquiring the altitude data to be fed to and to be used by the correlator;
• operating the millimeter sensor during cruising and overflight by back and forth scanning and in a substantially vertical down direction across a prescribed flight path to obtain the acquired altitude data;
• and
• occasionally pivoting the sensor about a horizontal axis, for scanning in the forward direction for purposes of searching for particular targets to be tracked subsequently of said altitude to the acquiring data.