Firejo
Member
I got my memory jogged by another post.
I had a support call to SeaTac airport about 13 years ago where one of our serial radios was “locking up”. It was a rack mount radio (SLC) connecting three SLC5/03’s via DF1. I’d never seen one of our radios lock up the way it was being described so I was somewhat skeptical but sure enough when I arrived (or I should say when we got to the control panel located in between the (then) two runways at SeaTac) I found the radio receiving serial data but not transmitting a thing. I cycled power and it took off and started running. I was then told that it happened whenever they turned on the battery charging system. The control panel was part of a taxiway lighting system and what I learned is that all taxi and runway lighting systems run strictly off of batteries that are charged as needed. This ensures that the lights won’t get interrupted during a power failure (not even for a fraction of a second). Anyway I noticed that below the PLC were 6 (or so) Coffey can looking devices with very large gauge wires coming out of one and into another linking all of them together. I asked what that was and was told that it was part of the battery charging system. I then asked what kind and how much voltage was involved. Turns out it was 3000VDC (yes, 3000VDC). I reached over and took my laptop back off the top of the panel and took about ten steps back (the cans were capacitors). I then noticed that the serial cable between the SLC and the radio was snaked through the cables connecting the caps together. We had the tower turn on the system (with me standing a good distance back) and sure enough the “data in” led came on pretty much solid. There was such a strong field that it was inducing huge amounts of noise onto the cable filling the radios buffer almost instantly. I’m kinda surprised it didn’t cook the radio. The airport tech I was with moved the cable and the problem went away. We then decided that we better go check the panel at the other end of the runways so we climbed into the airport tech’s truck where I figured we’d be going back to the access road and drive around. However we didn’t go that direction and shortly after starting to move the airport tech got onto the ground radio and asked permission to use the service road between the runways. The tower came back and granted him permission and added “just try to stay off of the runways”. By now it’s about 5:00pm on a Thursday afternoon and the airport is busy with landing about once every 30 seconds. I remember thinking, as a DC10 is landing no more than 50 yards from where we were how that was pretty good advice and I hoped this guy would follow it (he did).
The next morning on my way into work I heard that SeaTac was down to one runway and my heart sank. The lighting system that our modems were being used in was part of a “stop bar” system that was used to guide plans on the taxiways during heavy fog conditions. It was foggy that morning and I figured that the system went down again. When I got to the office I called the tech I was working with and asked what happened. He replied with a puzzled tone “what do you mean?” I told him that I heard that they were down to one runway at which point he started chuckling. He told me that they system was working flawlessly and it was because it was working that they were able to keep one runway open. Kinda made my day.
I had a support call to SeaTac airport about 13 years ago where one of our serial radios was “locking up”. It was a rack mount radio (SLC) connecting three SLC5/03’s via DF1. I’d never seen one of our radios lock up the way it was being described so I was somewhat skeptical but sure enough when I arrived (or I should say when we got to the control panel located in between the (then) two runways at SeaTac) I found the radio receiving serial data but not transmitting a thing. I cycled power and it took off and started running. I was then told that it happened whenever they turned on the battery charging system. The control panel was part of a taxiway lighting system and what I learned is that all taxi and runway lighting systems run strictly off of batteries that are charged as needed. This ensures that the lights won’t get interrupted during a power failure (not even for a fraction of a second). Anyway I noticed that below the PLC were 6 (or so) Coffey can looking devices with very large gauge wires coming out of one and into another linking all of them together. I asked what that was and was told that it was part of the battery charging system. I then asked what kind and how much voltage was involved. Turns out it was 3000VDC (yes, 3000VDC). I reached over and took my laptop back off the top of the panel and took about ten steps back (the cans were capacitors). I then noticed that the serial cable between the SLC and the radio was snaked through the cables connecting the caps together. We had the tower turn on the system (with me standing a good distance back) and sure enough the “data in” led came on pretty much solid. There was such a strong field that it was inducing huge amounts of noise onto the cable filling the radios buffer almost instantly. I’m kinda surprised it didn’t cook the radio. The airport tech I was with moved the cable and the problem went away. We then decided that we better go check the panel at the other end of the runways so we climbed into the airport tech’s truck where I figured we’d be going back to the access road and drive around. However we didn’t go that direction and shortly after starting to move the airport tech got onto the ground radio and asked permission to use the service road between the runways. The tower came back and granted him permission and added “just try to stay off of the runways”. By now it’s about 5:00pm on a Thursday afternoon and the airport is busy with landing about once every 30 seconds. I remember thinking, as a DC10 is landing no more than 50 yards from where we were how that was pretty good advice and I hoped this guy would follow it (he did).
The next morning on my way into work I heard that SeaTac was down to one runway and my heart sank. The lighting system that our modems were being used in was part of a “stop bar” system that was used to guide plans on the taxiways during heavy fog conditions. It was foggy that morning and I figured that the system went down again. When I got to the office I called the tech I was working with and asked what happened. He replied with a puzzled tone “what do you mean?” I told him that I heard that they were down to one runway at which point he started chuckling. He told me that they system was working flawlessly and it was because it was working that they were able to keep one runway open. Kinda made my day.
