Instrument Landing

Author: J.B. Hoag

At certain airports, a radio wave is transmitted on 93 MHz (wave-length of 3.23 m) to provide a glider path for "blind" or instrument landing. The pattern of field strength sent out for this purpose is indicated in Fig. 34 R.

Fig. 34 R. Glider path and indicator for instrument landing

A procedure for establishing the proper field pattern is described under wave guides. The glider path is indicated by the dotted lines of Fig. 34 R. If the plane is too far to one side of the correct path, a white-line pointer on the "intensity" meter in front of the pilot moves to one side, the movement resulting from the radio wave modulated by either a 62- or a 58-cycle note. Also, if the plane is too high or too low, a second pointer built into the same instrument will be moved up or down. The pilot need only keep the intersection of the two white pointers over the center dot. He will then glide onto the airport at the proper angle and in the path of the runway. Readings up and down are correct to within 50 feet. It must be a day of very poor visibility indeed if this is not close enough to see the land and bring the plane safely to earth.