Simple landing distance measurement with circular mark between aircraft and runway

Description herein is a system for simple distance measurement between an aircraft and circular mark in landing runway. The system includes an altimeter and a camera installed on the aircraft, and a circular mark placed on a landing runway. The camera on the aircraft must be oriented toward in front of the aircraft, and configured to detect the shape of the circular mark in image data and a flight control computer configured to calculate the angle between the aircraft and the ground, the ground range between the aircraft and the circular mark, and the slant range between the aircraft and the circular mark with the altitude information measured by the altimeter installed on aircraft. Accuracy of CDGPS used conventionally and proposed system is compared in analysis section, result shows proposed system has better performance if it uses high accuracy altimeter.