The one data format pilots are most familiar with is the METAR. You’ve read all about it in training and on pilot forums. In the U.S. they’re driven mostly by ASOS, the Automated Surface Observation System. Unfortunately this is covered a lot less in pilot training. But even in 2019 these systems are not infallible. We’ll go over this technology and help you understand what you need to know to stay safe.
The ASOS system was developed in the late 1980s to relieve the expense of maintaining human observers at hundreds of sites, improve consistency of observations, and bring high-quality observations to rural and remote airports. Much like NEXRAD it was a joint product of the FAA, NWS, and DoD, and was fielded at 1000 US airports between 1991 and 2004. Its main components are temperature, dewpoint, and wind sensors, along with new technology like sky condition, present weather, and visibility sensors.
