Operational Flight Testing of Early Instrument Landing Systems

The development of successful instrument approach and landing involved the solution of not only technical problems, but operational problems as well. A review of methods used to overcome operational problems is made, covering the period from the earliest successful instrument landing to the introduction of instrument approach into routine scheduled operation. Flight techniques are described, using early systems such as compass locator, constantintensity glide slope, and later, equisignal glide-slope facilities. Recognition of a requirement for visual aids to supplement electronic approach aids is outlined.