Narrative:

There were 3 arrivals landing runway 16; [all category 1 aircraft]. Aircraft X was first; followed by aircraft Y; followed by another aircraft. At the time of this event; the sun was down so the same runway separation minimum distances of 7110.65 paragraph 3-10-3a1 did not apply. For separation to exist; each preceding aircraft must clear the runway before the next arrival crossed the landing threshold.aircraft X landed runway 16. I instructed him to turn left taxiway A2. At this time I believed he was approaching the turn-off for taxiway A2. The pilot replied that he had passed A2. I responded that A2 should be right there off his left. As he continued down the runway I could see that he was past A2. I then told him to turn left on the reverse high speed A3. He passed A3 and I told him to turn left ahead. I wasn't too concerned about it at the time because I was going to have my 3;000 ft; and I was distracted by my error in determining his position in relation to taxiway A2. I was looking at the lights on taxiway A2 trying to figure out what I had gotten wrong. That was when I realized that the lights for taxiway A2 are significantly dimmer that the other taxiway lights in the vicinity. And I had completely missed about 3 taxiway lights on the north side of taxiway A2. Not seeing these lights led me to misjudge aircraft X's position in relation to taxiway A2. At the time of my last instruction to aircraft X; aircraft Y was on short final for runway 16 with aircraft X approaching the turn off for taxiway D. Aircraft X did not exit at taxiway D. I wasn't aware of this at the time because I was looking at taxiway A2. Aircraft Y crossed the landing threshold and touched down about taxiway A1. At this time aircraft X was finally exiting the runway at the runway 27 intersection. The distance between these two aircraft while they were both on the runway was about 3;200 ft (figured as the distance between the A1 intersection and the runway 27 intersection). I should have sent aircraft Y around because it was after sunset and required separation was a clear runway; not 3;000 ft. Recommendation; this problem with the A2 lights has not always existed; it must be something new. A couple of weeks back there was a problem with the electrical wiring for some of these taxiway lights involving A2. At that time I remember one of the airport operations personnel indicated that the problem was related to electrical work being done in conjunction with a construction project. I think now that these lights not being the same intensity may be related to the construction. I am now aware of the different intensities of the lights on taxiway A2 and particularly the previously overlooked lights on the north side of taxiway A2; so I know better now when an aircraft has passed that exit. If we had more traffic at night; that would also help. I can't remember the last time I had three closely spaced successive arrivals at night. Had this occurred during daylight hours it would be a non-event; but the rules at night are different. I have talked to other controllers about the lights and pointed out the hard-to-see lights on the north side of A2.

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Original NASA ASRS Text

Title: FTW Controller experienced a loss of separation event between successive night time arrival aircraft when one failed to make a timely exit from the runway; the reporter listing varied taxiway lighting intensities as having contributed to the error.

Narrative: There were 3 arrivals landing Runway 16; [all Category 1 aircraft]. Aircraft X was first; followed by Aircraft Y; followed by another aircraft. At the time of this event; the sun was down so the Same Runway Separation minimum distances of 7110.65 Paragraph 3-10-3a1 did not apply. For separation to exist; each preceding aircraft must clear the runway before the next arrival crossed the landing threshold.Aircraft X landed Runway 16. I instructed him to turn left Taxiway A2. At this time I believed he was approaching the turn-off for Taxiway A2. The pilot replied that he had passed A2. I responded that A2 should be right there off his left. As he continued down the runway I could see that he was past A2. I then told him to turn left on the reverse high speed A3. He passed A3 and I told him to turn left ahead. I wasn't too concerned about it at the time because I was going to have my 3;000 FT; and I was distracted by my error in determining his position in relation to Taxiway A2. I was looking at the lights on Taxiway A2 trying to figure out what I had gotten wrong. That was when I realized that the lights for Taxiway A2 are significantly dimmer that the other taxiway lights in the vicinity. And I had completely missed about 3 taxiway lights on the north side of Taxiway A2. Not seeing these lights led me to misjudge Aircraft X's position in relation to Taxiway A2. At the time of my last instruction to Aircraft X; Aircraft Y was on short final for Runway 16 with Aircraft X approaching the turn off for Taxiway D. Aircraft X did not exit at Taxiway D. I wasn't aware of this at the time because I was looking at Taxiway A2. Aircraft Y crossed the landing threshold and touched down about Taxiway A1. At this time Aircraft X was finally exiting the runway at the Runway 27 Intersection. The distance between these two aircraft while they were both on the runway was about 3;200 FT (figured as the distance between the A1 Intersection and the Runway 27 Intersection). I should have sent Aircraft Y around because it was after sunset and required separation was a clear runway; not 3;000 FT. Recommendation; this problem with the A2 lights has not always existed; it must be something new. A couple of weeks back there was a problem with the electrical wiring for some of these taxiway lights involving A2. At that time I remember one of the Airport Operations personnel indicated that the problem was related to electrical work being done in conjunction with a construction project. I think now that these lights not being the same intensity may be related to the construction. I am now aware of the different intensities of the lights on Taxiway A2 and particularly the previously overlooked lights on the north side of Taxiway A2; so I know better now when an aircraft has passed that exit. If we had more traffic at night; that would also help. I can't remember the last time I had three closely spaced successive arrivals at night. Had this occurred during daylight hours it would be a non-event; but the rules at night are different. I have talked to other controllers about the lights and pointed out the hard-to-see lights on the north side of A2.

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.