Research on TCH and RDH of Glide Path Equipment

There is a certain difference between the RDH obtained from the flight inspection and the TCH calculated from geometry terrain. The problem is always neglected and someone attribute the cause of poor RDH to equipment issues, actually equipment is a problem, but the electromagnetic environment is also a very important factor overlooked by owner. When the electromagnetic environment around glide path antenna is worse, the difference of TCH and RDH is even larger, and even cannot meet the requirements for safe operation. This article study the calculation method of the actual measured RDH, revealing fundamental reason of the difference, and further explaining the importance of protecting the electromagnetic environment of the instrument landing system,.providing analysis ideas and solutions for equipment construction and maintenance engineers.