AN/APN-4 LORAN Set

The APN-4 was the first LORAN set for aircraft to enter service. It had a separate receiver and display unit. The navigator had a leather hood to put over the oscilloscope’s cathode ray tube so he could clearly see it in daylight. LORAN was most valuable when the skies couldn’t be seen for celestial navigation and when coastlines couldn’t be picked up by radar. It did require a skilled operator.