Narrative:

I was working local control. Landing and departing runways 30 left/right. Arrivals were spaced minimally to get one departure out between arrivals; but just about everyone was 'tight'. There were gusty winds (310 at 25 gusting 35) with gains and losses of 10-15 knots. The ground speeds of the arrivals were pretty slow due to the winds; but it seemed that they were not consistent with maybe one out of 5 arrivals at 'normal' ground speeds. This made the situation much more difficult to judge whether or not to 'go in' with a departure.I had put aircraft X into position on runway 30L with aircraft Y on approximately 3 mile final. After the previous arrival was clear of the runway; I then cleared aircraft X for takeoff. After the takeoff clearance was issued; an aircraft in the que for runway 30L asked about their sequence. I looked down at my board briefly to check where I wanted them and then told them to 'stand by'. When I looked up to check the status of the departure I saw they were rolling approximately 4;000 feet down the runway. I then began looking for aircraft Y to determine their position. I was looking at short final where I expected to see them. I was unable to find them for a moment. They then appeared from behind a post between two of the panes of glass approximately 1;000-1;500 feet down the runway and in a flare to land. At this time aircraft X was well into their rotation and just lifting off.I made the determination not to send aircraft Y around due to their proximity to the ground and the fact that aircraft X was now airborne. I am not sure if the arrival was faster than anticipated or the departure rolled slower than anticipated.in this particular situation with the winds and minimal spacing between arrivals my workload was much too high to be talking to the aircraft inquiring about their sequence. I should have been focused on aircraft Y's ground speed and location as well as aircraft X's departure roll. I should have asked for additional space between arrivals from approach.

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Original NASA ASRS Text

Title: A Tower Controller reported clearing an aircraft for takeoff in between two landing aircraft. The Controller did not notice that the second arriving aircraft was past the landing threshold when the departure was only 4;000 feet down the runway.

Narrative: I was working Local Control. Landing and departing Runways 30 L/R. Arrivals were spaced minimally to get one departure out between arrivals; but just about everyone was 'tight'. There were gusty winds (310 at 25 gusting 35) with gains and losses of 10-15 knots. The ground speeds of the arrivals were pretty slow due to the winds; but it seemed that they were not consistent with maybe one out of 5 arrivals at 'normal' ground speeds. This made the situation much more difficult to judge whether or not to 'go in' with a departure.I had put aircraft X into position on Runway 30L with aircraft Y on approximately 3 mile final. After the previous arrival was clear of the runway; I then cleared aircraft X for takeoff. After the takeoff clearance was issued; an aircraft in the que for Runway 30L asked about their sequence. I looked down at my board briefly to check where I wanted them and then told them to 'stand by'. When I looked up to check the status of the departure I saw they were rolling approximately 4;000 feet down the runway. I then began looking for aircraft Y to determine their position. I was looking at short final where I expected to see them. I was unable to find them for a moment. They then appeared from behind a post between two of the panes of glass approximately 1;000-1;500 feet down the runway and in a flare to land. At this time aircraft X was well into their rotation and just lifting off.I made the determination not to send aircraft Y around due to their proximity to the ground and the fact that aircraft X was now airborne. I am not sure if the arrival was faster than anticipated or the departure rolled slower than anticipated.In this particular situation with the winds and minimal spacing between arrivals my workload was much too high to be talking to the aircraft inquiring about their sequence. I should have been focused on aircraft Y's ground speed and location as well as aircraft X's departure roll. I should have asked for additional space between arrivals from approach.

Data retrieved from NASA's ASRS site 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.