Monday, November 14, 2011

Air Weather Service Operations at Goodfellow Air Force Base in the 1960's

I was stationed at Goodfellow Air Force Base (AFB) in San Angelo, Texas, in the mid-1960's. Here is a look back in history by way of a short account of what went on at Goodfellow AFB then.

Goodfellow AFB had been a pilot training base during World War II. In 1958 pilot training ceased and the base assumed the mission of teaching young officers, mostly second lieutenants straight out of college, their jobs in the US Air Force. Their career field was called Security Service and their jobs were to work in, and be managers of, units that collected intelligence data by listening in on other people's communications.

Balloon Detachment

The other activity on the base was our weather detachment. It was an Air Weather Service unit, but the actual weather people were in the minority. Most of the detachment consisted of balloon riggers, aircraft maintenance people, and aircrews. The detachment's mission was to get air samples from high up in the atmosphere - 60,000 to 120,000 feet up. The way the samples were obtained was through the use of high altitude balloons. The air samples were then passed to the Atomic Energy Commission for analysis. The purpose was to determine who in the world (besides the US) was testing atomic weapons. No one advertised the fact that they were going to detonate an atomic bomb to test its effectiveness, but it was known that several countries were testing. Naturally, the US was most concerned about the Russians and the Chinese. Scientists of the Atomic Energy Commission could actually tell who was blowing stuff into the atmosphere by examining the minute particles that floated around the globe at great heights after a test.

The balloons looked like huge plastic bags, about a quarter of a mile long, that were stretched out on the runway on a carpet to protect them. Precisely the right amount of helium was pumped into the balloons to bring them to their intended altitude and to make them float there. Attached to these balloons were large electric motors that activated large fans that blew air across very fine filters. Tiny particles would be trapped by the filters. At those altitudes, the fans had to blow a lot of the thin air onto the filters to be able to get a sufficient sample of the radioactive debris. So, one of the higher altitude flights might take 10 to 12 hours. After it was determined that enough of a sample was obtained a signal from the ground initiated an electric spark that cut the connection between the balloon and the payload (motors, filters, blowers) which would then fall to earth suspended by several giant parachutes. Relieved of the weight of the payload, the balloon would rise and finally burst into a million tiny pieces that became part of the floating debris in the atmosphere.

The launching of the balloon was a spectacle in itself. First of all, it had to be done without any wind, usually at sunrise. The payload would be positioned on a large truck. The end of the balloon, which was attached to the payload, would be clamped tight unto a special clamp on the truck. As helium was pumped into the balloon, it slowly rose. This is where it had to be wind still, because now the truck maneuvered under the slowly rising balloon so that at the moment when the balloon was completely off the ground and vertically over the truck, the clamp could be released so that the payload would rise smoothly without hitting the ground. It happened now and then that a small breath of air caught the balloon, which looked like a giant sausage skin, twisting it or even sending it back to the ground and tearing it. Or the payload was released too soon and it crashed unto the ground. To prevent the latter mishap, a launch controller with a headset stood on the truck bed, strapped to the cab of the truck, giving directions to the driver because the driver had to concentrate on steering the truck and could not see the balloon once it was straight overhead.

The unit had four H-21 helicopters and a C-47 transport aircraft assigned. The four helicopters were stationed on the base, the C-47 with a special glass bubble on top was stationed at the municipal airport of San Angelo because the runway on Goodfellow AFB was used for launching the balloons. When the balloon was successfully launched, the C-47 would take off and follow it, someone in the glass dome keeping it in sight all the time. Of course, the C-47 could not go to the heights that the balloons went, therefore the balloons were kept in sight with field glasses. Two of the helicopters would leap-frog from one airport to another along the path of the balloon, which was being relayed by the C-47. When the payload landed, one of the helicopters would fly there, land in some farmer's field or on a road, retrieve the payload, and bring it back. It is not surprising that people in the Southwest occasionally thought they saw UFO's and little green men carrying away what they thought were parts of a crashed space ship. Sometimes the helicopters would have to go well into Louisiana, 400 or 500 miles from San Angelo to retrieve the payload, depending on the winds.

Air Weather Service Involvement

Whereas the balloon launchers and air crews were specialists in their fields, they were not trained weather observers or forecasters. It was the weathermen's job to determine what the weather would be like for the next day's launch, how strong the winds would be, and if there were going to be clouds. There were high level meetings almost like those for a space launch. A "go, no-go" decision was made the day before the launch based on the forecasters' prognosis because a flight plan had to be filed with the FAA well in advance and the helicopters and the C-47 had to be prepared for the time and distance that was anticipated that they would have to be underway. In addition to the calm winds at launch time there could not be more than scattered clouds along the flight path because the balloon had to be able to be kept in sight by the C-47 and by all other aircraft in the area.

Weather Station

There were two sections to the actual weather support team. One section consisted of weather observers and weather forecasters. It was the observers' job to monitor the four or five teletype machines, post the weather reports that came in over teletype, and plot maps so that the forecasters could make their forecasts. This part of the job was just like in a regular weather station. The difference was that the observers didn't take any weather observations and the forecasters only made specialized weather forecasts for the balloon launches and flights.


The other section of the weather support team was a RAWINSONDE section. A RAWINSONDE ("sonde" is French for probe) is a piece of equipment for use with weather balloons that measures various atmospheric parameters and transmits them to a fixed receiver. In those days, a RAWINSONDE measured temperature, humidity, and atmospheric pressure and transmitted these data via radio signal. The signal was tracked with a circular antenna similar to a radar antenna that locked on to the radio signal from the unit on the weather balloon once the antenna was manually pointed at the ascending unit (which was not always easy if the balloon took off rapidly or a cloud bank suddenly swallowed it before a good manual fix could be established). Today, with GPS and other technical innovations, RAWINSONDE operations are probably quite a bit different.

A RAWINSONDE team consisted of three to four operators. They would calibrate the sensors and the transmitter before sending them aloft. Meanwhile, another part of the team filled the balloon with the calculated amount of helium to allow it to go to the required altitude. The balloons used for RAWINSONDE were much smaller than the balloons used to collect the atmospheric samples, but they had to reach the same altitudes as the balloons with the payload to get an accurate picture of what wind speeds and directions the research balloons would encounter on their ascent and at their designated floating altitude. The weather balloon was tied to a paper parachute with about 60 feet of string which in turn was attached by another 60 feet of string to the RAWINSONDE instrument which was about the size of two shoe boxes put together. The paper parachute served the purpose of bringing the instruments back to earth slowly enough after the balloon burst so that it would not kill anyone or otherwise do serious damage. The instrument was only used one time, no effort to retrieve it was made. If, for some reason, the balloon burst before reaching the required altitude, the whole procedure had to be repeated until the correct altitude was reached, which happened occasionally.

When releasing the weather balloon it was often the case that the person holding the instrument, which was attached to the balloon by the 120 foot train, had to run quite a distance before the balloon was high enough so that he could let the instrument go. The procedure was quite similar to that followed by the launchers of the big balloons, except that it all had to be done on foot. Sometimes the wind was so strong that the balloon took off horizontally instead of vertically and the operator had to run very fast or the instrument would hit the ground and the whole procedure from calibrating the instrument to the filling and releasing of the balloon would have to start all over.

As the antenna tracked the RAWINSONDE, one person would read the azimuth angle (horizontal direction) in which the antenna was pointing and the distance of the airborne instrument from the antenna and call them out to another person who would plot them on a round board. This way the wind speed and direction could be calculated by the way the balloon was moving. At the same time another person would convert the pressure readings to altitude values and plot them and the corresponding temperature and humidity readings on a board that represented a vertical cross section of the atmosphere. When the "run" was finished the results were passed to the forecasters and transmitted for the rest of the weather community to use.

I was fortunate to have worked both in the weather station as well as a RAWINSONDE operator. Even though the work in the weather station was all done on an eight-hour day shift and the RAWINSONDE operations took place during night shifts that regularly lasted 10 to 12 hours, sometimes more depending on mission requirements, I opted to switch to the upper air operation when a shortage on that team occurred just to get the experience. It was an experience that few others in Air Weather Service can claim.