Narrative:

I was the only controller scheduled till [a future time]. Being the only controller; I was working all the positions in the control tower. At XA05z there was a power bump. This shut down literally everything in the control tower. This is becoming a routine occurrence at tucson tower; but I had never had this happen while I was alone. The power returns after only a few seconds. The problem is that many of the computers take a while to restart. The radios also will not transmit for approximately another 15 to 20 seconds. The stars at LC1 will eventually return to emergency service mode; the stars at LC2 will return to full service mode. At this point; operations are moved over to the other side of the control tower to LC2. This shut down happened while I was working with multiple aircraft on the different positions. I do not remember the traffic scenario; I do remember at least two taxiing aircraft. Where I made an error was I approved aircraft X to cross both 11L and 11R behind a departure. There was an additional aircraft holding short of 11L for departure. At that point I decided I had an opportunity to make the transfer to the LC2 position. I entered the lengthy series of keystrokes to place the stars into the correct mode as well as selecting and deselecting all the radios. At this point I cleared the other aircraft for departure. I had assumed the aircraft X aircraft had completed the crossing. Where I made the correction was immediately after I had given the takeoff clearance I made my routine runway scan. I believe the other aircraft did not cross the hold line by the time I informed him of the runway crossing. I informed him of my error; told him the aircraft would be done crossing in 2 seconds; and then told him he was still cleared for takeoff. I think my error was minor; more than anything because of my disciplined runway scans. But more than that; the power bumps. There was an additional power bump at XA20z. This subsequent power bump was not that big of a deal because the position transfer had taken place. I do not want to get anybody in any trouble but I am a little upset about the equipment situation because after speaking with a maintainer it is my understanding that the maintenance personnel are fully aware of what it takes to fix the problem. The FAA just will not fund the equipment. I am not sure if the maintainer was necessarily supposed to inform me of that. On this day I happened to be able to handle it; but I fear the day that this power bump happens to me while I have a pattern full of F16s; cessnas; and airliners. I should not even have to think about a power bump while I am working with this type of traffic pattern. I think that in the last 2 months; I alone have dealt with over 5 power bumps. I am not going to say that a repair of the equipment will prevent this from happening again. This is my problem. In order to prevent this from happening again the runway scan will take place specifically before a takeoff clearance; as opposed to during or immediately after. Also; no matter the situation; I will force my self to slow down.

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Original NASA ASRS Text

Title: TUS Tower Controller reports ongoing power issues which cause equipment problems and contributed to a ground conflict.

Narrative: I was the only Controller scheduled till [a future time]. Being the only Controller; I was working all the positions in the control tower. At XA05z there was a power bump. This shut down literally everything in the control tower. This is becoming a routine occurrence at Tucson Tower; but I had never had this happen while I was alone. The power returns after only a few seconds. The problem is that many of the computers take a while to restart. The radios also will not transmit for approximately another 15 to 20 seconds. The STARS at LC1 will eventually return to emergency service mode; the STARS at LC2 will return to full service mode. At this point; operations are moved over to the other side of the control tower to LC2. This shut down happened while I was working with multiple aircraft on the different positions. I do not remember the traffic scenario; I do remember at least two taxiing aircraft. Where I made an error was I approved Aircraft X to cross both 11L and 11R behind a departure. There was an additional aircraft holding short of 11L for departure. At that point I decided I had an opportunity to make the transfer to the LC2 position. I entered the lengthy series of keystrokes to place the STARS into the correct mode as well as selecting and deselecting all the radios. At this point I cleared the other aircraft for departure. I had assumed the Aircraft X aircraft had completed the crossing. Where I made the correction was immediately after I had given the takeoff clearance I made my routine runway scan. I believe the other aircraft did not cross the hold line by the time I informed him of the runway crossing. I informed him of my error; told him the aircraft would be done crossing in 2 seconds; and then told him he was still cleared for takeoff. I think my error was minor; more than anything because of my disciplined runway scans. But more than that; the power bumps. There was an additional power bump at XA20z. This subsequent power bump was not that big of a deal because the position transfer had taken place. I do not want to get anybody in any trouble but I am a little upset about the equipment situation because after speaking with a Maintainer it is my understanding that the maintenance personnel are fully aware of what it takes to fix the problem. The FAA just will not fund the equipment. I am not sure if the Maintainer was necessarily supposed to inform me of that. On this day I happened to be able to handle it; but I fear the day that this power bump happens to me while I have a pattern full of F16s; Cessnas; and airliners. I should not even have to think about a power bump while I am working with this type of traffic pattern. I think that in the last 2 months; I alone have dealt with over 5 power bumps. I am not going to say that a repair of the equipment will prevent this from happening again. This is my problem. In order to prevent this from happening again the runway scan will take place specifically before a takeoff clearance; as opposed to during or immediately after. Also; no matter the situation; I will force my self to slow down.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.