 After World War II, the U.S. Navy and United Airlines worked together on various methods at the U.S. Navy's "Landing Aids Experimental Station" located at the Arcata–Eureka Airport, California air base, to allow aircraft to land safely at night and under zero visibility weather, whether it was rain or heavy fog.The predecessor of today's modern ALS while crude had the basics — a 3,500 foot visual approach of 38 towers, with 17 on each side, and atop each 75 foot high tower a 5000 watt natural gas light.After the U.S. Navy's development of the lighted towers it was not long before the natural gas lights were soon replaced by more efficient and brighter strobe lights, then called Strobeacon lights.