If you thought that Leeds Bradford Airport (LBA) in the north of England was one of the airports most frequently closed because of fog, you obviously have never heard about Arcata–Eureka Airport (ACV) in Northern California.
Located in Humboldt County, 270 miles north of San Francisco, Arcata–Eureka Airport (ACV) is considered to be the foggiest airport in the world. The weather in this part of Northern California is so unpredictable that the United States military has made it a base for its all-weather training.
A Douglas DC-3 made the first blind landing at ACV in 1947
Because the area was often shrouded in fog, the United States Navy constructed the airport during World War Two to test its defogging systems. Following the war, the airport was opened up to commercial airliners, and in December 1947, a Southwest Airlines DC-3 became the first civilian passenger airline to make a blind landing.
The blind landing was made possible thanks to Ground-Controlled Approach (GCA) radar and an Instrument Landing System (ILS). Arcata–Eureka Airport (ACV) is particularly prone to fog as it is only 400 yards from the Pacific Ocean. On average, the airport suffers from dense fog or rain 97 days a year.
SkyWest Airlines and Avelo are the only two airlines that fly to ACV
Acting mainly as a feeder airline for United Airlines flights departing from San Francisco, SkyWest Airlines, operating as United Express, offers three or four flights daily using Canadair CRJ-200 and Embraer 175 regional jets to San Francisco International Airport (SFO). The only other airline flying into and out of ACV is Avelo Airlines, a recent start-up based at Hollywood Burbank Airport (BUR) in Los Angeles. Avelo flies to ACV using a Boeing 737-800, which is the largest aircraft currently serving the airport.
How fog affects travel
Dense fog tends to only occur during colder months of the year, but it is possible to have foggy days in the spring and the autumn. One thing to bear in mind is that fog can be very localized, which means where you live may be fine, but a few miles away at the airport, it can be fogged in. As we mentioned, you are most likely to encounter fog in the late fall or during the winter, when conditions tend to be colder and the nights are longer. Fog is often the result of clear night skies and very little or no wind. As the land’s surface cools overnight, it reduces the ability of the air to hold moisture, allowing for condensation and fog to occur close to the ground.
More often than not, fog will disperse after sunrise, but on some occasions can linger well into the afternoon, and even on some occasions persist for several days. For meteorologists, the ability to forecast fog can be very tricky. Fog forms when the moisture in the air reaches its dew point. It then condenses from water vapor into water droplets. This is the same effect you get on a bathroom mirror when moisture in the air comes into contact with a cold surface. While water vapor is transparent, water droplets reflect light, reducing visibility. When this visibility goes below 3,280 feet, it is officially called fog.
For aviation purposes, the definition of fog is a visibility of less than 3,200 feet. For the public and motorists, a limit of 700 feet is more realistic. When visibility falls below 200 feet, severe disruptions appear.