Weather robots

May 1, 1993

"Show me" is the battle cry of Missouri, where folks like to see proof rather than just hearing that something is going to be good for them. Many pilots have taken a "show me" attitude toward the National Weather Service's modernization program.

When I first heard about the new ASOS (automated surface observing system), which is a successor to AWOS (automated weather observing system), my initial reaction was "big deal." We have plenty of weather observation locations now, staffed by trained observers who provide hourly sequence reports that instantly grade a forecast's validity. Why is this new automation important? However, my interest was piqued when reviewing the accident records. Over the years, weather has claimed more hard-headed pilots (not just from Missouri) than any other single probable cause.

In a number of cases, pilots didn't believe the forecast and may not have had access to actual reports. ASOS isn't going to do much for forecasting, at least initially, but it may help nowcasting considerably. Nowcasting is reporting what the weather is doing, and there's nothing like a real-time view of the elements along the route and at the destination to help the decision-making process. At airports where there are human observers, ASOS won't have the marked effect that it will at smaller airports out in the boonies.

For example, here in Frederick, Maryland, we have an ILS and a recently commissioned AWOS at a nontowered airport. Thanks to a nearby river and its attendant fog, the ILS is used frequently. Prior to the commissioning of the AWOS, the local FBO staff would provide the altimeter setting (most of the time) on the unicom frequency up until 9 p.m., after which you were obliged to use the Washington-Dulles altimeter setting. Having the local altimeter setting, provided by AWOS, lowers the landing minimums by 120 feet. This feature alone has saved numerous diversions to Baltimore or Dulles. It's also nice to know when there's a 500-foot overcast and the visibility is a mile.

The automated observations are not always right, but then I didn't expect them to be. This is one of those areas where you can get indignant about technology not living up to its promise. My thought is that we have been living with inaccurate fuel gauges and winds aloft forecasts since the earth cooled and have managed to survive rather nicely when our expectations have been salted with skepticism. It takes time to calibrate and to work the bugs out of the system.

Some of the other capabilities of ASOS/AWOS are not the same as a human observer, and this has stirred some controversy about whether the systems will provide "equal or better" service as mandated by Congress for the NWS modernization program. This new technology is complex and will evolve over the coming years. There are those who are adamantly opposed to automated weather observation because of some equipment limitations that may lead some unsuspecting pilot down the primrose path. Detecting certain types of precipitation, towering cumulus clouds, lightning, and other weather happenings are not yet within the new systems' capabilities and, with certain phenomena, will never be in the repertoire. But remember that automated weather observers aren't our only source of information. Between weather radar, pilot reports, satellite pictures, and other sources, no pilot should ever be unsuspecting. Most of us have been snookered often enough by weather to not take anything on blind faith, including human or automated observations.

The AOPA Air Safety Foundation, working with a grant from the NWS and the FAA, is developing a comprehensive pilot education program on ASOS/AWOS/ATIS to help you to understand the strengths and weaknesses of these automated systems. This program will include information cards, a pamphlet, a video, and slide presentations to be given at future safety seminars. Flight instructors will learn about the systems through refresher clinics and the ASF's Flight Instructor Safety Report.

Pilots should know about ASOS and AWOS. We need to gather as much information about the weather as possible to improve our decision-making. ASOS/AWOS gives us information we haven't had before. This technology, used correctly, will give instant feedback on how a forecast is doing in as many as 400 more locations than we have now. It will help preflight and in-flight planning.

The ASF will also be evaluating the new systems with your help. If you don't understand how they work, attend a seminar or call for a pamphlet (these should be available by late summer). If a system is miscalibrated and says it's clear below 12,000 and you're in the soup at 1,200, let us know. I'm suspicious in dealing with the new technology. It isn't perfected in the laboratory, but out on the job. The fact that the technology isn't perfect doesn't mean we shouldn't start using it. It also means that the NWS will have to "show us" that it can be responsive when a system says it's snowing, and the outside temperature is 83 degrees.


See also the index of "Safety Pilot" articles, organized by subject. Bruce Landsberg is executive director of the AOPA Air Safety Foundation.