Lights guided early airmail planes

Completion of the transcontinental railroad in Utah in 1869 was a milestone in the state's transportation legacy. But a lesser-known key travel event took place over Utah in the early 1920s when the first airmail planes crossed the continent.

Using planes to deliver mail shaved 22 hours off coast-to-coast mail delivery by the former all-railroad system. But mail still had to be put on trains when the sun went down each day because airplane flights at night were considered too dangerous.

In those days, pilots were forced to truly fly by the seat of their pants, lacking radar and most of today's sophisticated navigation technology. Theirs was a simple "fly by sight" system. Even their so-called instrument panel had to be painted with luminous paint.

The U.S. Postal Service, operator of those early planes in the 1920s, was under pressure to increase the speed of mail delivery. The only quicker alternative was to fly at night. Previously, mail was flown at night only over the flat 885 miles between Chicago and Cleveland.

In 1921, the U.S. Army began installing rotating beacons along the coast-to-coast route to assist navigation at night, according to information from the National Archives of the U.S. Post Office.

Creating a lighted air corridor from Rock Springs to Salt Lake City cost $29,234 for the 169 miles.

The 417-mile flight from Cheyenne to Salt Lake City had three regular airfields, 20 emergency airfields, 16 electric beacons and 75 gas-powered beacons, the 1925 annual report from the postmaster general said.

By July 1, 1924, some 185 beacons of three different configurations were in place over 2,669 miles from New York to San Francisco, and the first nighttime delivery was made.

Utah was a key Western component to this path. One beacon was installed on "Big Beacon," a 7,143-foot mountain east of Salt Lake City and directly east of 200 South Street. (Today, this peak is more commonly known as Wire Mountain.) This peak has microwave relays on top of it, as well as an old fire lookout tower.

The high-intensity beacons were placed on 53-foot towers about 10 miles apart. They contained a 24-inch parabolic mirror and a 1,000-watt bulb. They could emit a 1 million candlepower flash every 10 seconds.

The beacons revolved six times per minute and were visible to pilots on clear nights from as far as 75 miles away. Beacons were maintained regularly, and some could only be reached by foot or on mule. Surprisingly, historical reports indicate it was ultimately harder to install the lights in the populated Eastern United States than the mountainous West.