Narrative:

I was working the local control position at ZZZ ATCT. It was a busy night session further complicated by weather in the area. As I took the position there were many aircraft lined up for departure and I felt some pressure to get them out quickly. I was in 'launch mode.' while I was working; east traffic was stopped. This meant the eastbound aircraft on my frequency had to be taken out of line and parked. When a new route became available; I informed the pilot to go over to clearance delivery to receive it. Ground control was very busy when the eastbound traffic got stopped. To relieve taxiway congestion and workload; ground control asked to park aircraft Y on twy 'P'. This meant having aircraft Y cross runway xxr; the departure runway at taxiway juliet. I was departing a heavy jet at the time ground made the request. Since I would have to wait for the wake turbulence interval and would be crossing my own arrival traffic down field anyway; any loss of departure slots would be minimal so I approved the request. Due to the fact that ground was busy and I was concerned about the timeliness of the runway crossing; I physically watched and heard ground control immediately issue crossing instructions to aircraft Y as the departing heavy jet cleared the intersection of taxiway juliet at runway xxr. I then began crossing my own arrival traffic further down field. While this was happening; a few distractions occurred. Aircraft X; another eastbound departure that I had on frequency parked between the runways called me. I answered the pilot; and he informed me that he would need more time to prepare for departure because he could not accept the new routing he had received. While this was going on; it became evident that due to a printer malfunction; we were not getting any arrival strips. Since many strips were missing; the coordinator; who would normally be standing between local and ground control got busy hand writing arrival strips for most every arrival. I acknowledged aircraft X and went back to what I had been doing. I scanned my runway and observed it to be clear. I then cleared aircraft Z; who had been holding in position; for take off. Aircraft Z accepted the clearance and began take off roll. A few seconds later the amass/asde alerted 'warning runway xxr occupied'. I first thought it to be a false alert; since we get so very many of these but I immediately looked up at the display. I saw the aircraft Z and the aircraft Y icons flashing. I looked out the window and saw aircraft Z on take off roll and aircraft Y stopped at taxiway juliet; facing runway xxr. I heard ground control telling aircraft Y to hold short of runway xxr. It appeared aircraft Y was possibly across the runway hold short line; but short of the white runway edge line. I attempted to stop aircraft Z's take off roll but it was too late. After the alert when off; I realized that the reason the runway had been clear when I scanned it was that for some unknown reason; aircraft Y had delayed his runway crossing for so long; that my arrival aircraft had time to cross runway xxr; clear on the other side. I also had answered aircraft X's transmission about his routing. In the meantime; for some unknown reason aircraft Y had not even begun his runway crossing even though he was instructed to do so immediately after the departing heavy jet had rolled through the intersection. I believe this delay was 'the setup' for this error when combined with the other factors. I normally use good runway safety technique. I do in fact I have a technique in place to prevent a runway crossing error. Any time I am crossing a runway with an aircraft down field and have an departure in position; I turn the departing aircraft's flight progress strip over face down on the counter so that I cannot see the call sign and therefore; cannot clear the aircraft for take off. Before I clear any aircraft for take off; I scan the runway physically; and then scan the amass/asde display to back up the visual scan. During this session the distractions of stopped aircraft; re-routing; missing strips and ground control's unusual request to cross runway xxr were distracting enough that I neglected to turn aircraft Z's flight strip over face down on the counter; as well as look up and do my usual back-up scan of the amass/asde. Normally; the coordinator would also have been a part of the process and been an extra set of eyes and ears; but he was not available due to the fact that he was writing arrival strips. Recommendation; I have been working at ZZZ for almost many years in it's current configuration. I very clearly remember how the ZZZ ATCT was configured when the new tower was first commissioned. The amass/asde displays were set on the counter. I believed this was the ideal setup. Having the amass display on the counter meant it fell more naturally in view when scanning the runways out the window. A few months later; due to the fact that the asde displays were hung from the ceiling in the old tower and most of the fpl's were used to having them there; the decision was made to alter the configuration and hang the displays. This current configuration now requires the local controller to look up and opposite the direction of departure traffic when on runway xx. Had I scanned the amass/asde display; it is likely I would have seen aircraft Y's data block at taxiway juliet and not cleared aircraft Z for take off. If the display was on the counter; perhaps even with the other distractions present; I would have been more successful in keeping that in my scan. I don't expect that any tower configuration changes to take place based on this event. I know how difficult that can be. We are working in a busy; complex environment. I do believe minimizing distractions will go a long way towards preventing runway incursions. As with most errors; there were multiple factors mentioned that contributed to the final event. Any event that is 'out of the ordinary' is known to be a contributing cause towards operational errors. In this case; the ground controller's request to cross runway xxr at taxiway juliet was a request that was out of the ordinary for me in this operational configuration. In the future; in addition to turning the flight progress strip face down; I intend to place a plastic flight strip holder on top of the strip whenever another control position is crossing a runway under my control and I have an aircraft in position. I also believe that if aircraft Y had been on my local control frequency and I had cleared him across runway xxr; 1; he would have been 'top of mind' and not as easily overlooked as he delayed on taxiway juliet. 2; aircraft Y would have heard the take off clearance for aircraft Z as well as aircraft Z hearing the clearance for aircraft Y to cross runway xxr. That being the case; I would make the recommendation that an aircraft that is going to cross a main departure/arrival runway and stay on taxiways under local control's control be on local control's frequency.

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Original NASA ASRS Text

Title: Local Controller described an AMASS detected runway ground conflict when traffic crossing the departure runway on Ground frequency had not completely cleared the runway when a take off clearance was issued.

Narrative: I was working the Local Control position at ZZZ ATCT. It was a busy night session further complicated by weather in the area. As I took the position there were many aircraft lined up for departure and I felt some pressure to get them out quickly. I was in 'launch mode.' While I was working; East traffic was stopped. This meant the Eastbound aircraft on my frequency had to be taken out of line and parked. When a new route became available; I informed the pilot to go over to clearance delivery to receive it. Ground Control was very busy when the Eastbound traffic got stopped. To relieve taxiway congestion and workload; Ground Control asked to park Aircraft Y on TWY 'P'. This meant having Aircraft Y cross Runway XXR; the departure runway at Taxiway Juliet. I was departing a heavy jet at the time ground made the request. Since I would have to wait for the wake turbulence interval and would be crossing my own arrival traffic down field anyway; any loss of departure slots would be minimal so I approved the request. Due to the fact that ground was busy and I was concerned about the timeliness of the runway crossing; I physically watched and heard ground control immediately issue crossing instructions to Aircraft Y as the departing heavy jet cleared the intersection of Taxiway Juliet at Runway XXR. I then began crossing my own arrival traffic further down field. While this was happening; a few distractions occurred. Aircraft X; another Eastbound departure that I had on frequency parked between the runways called me. I answered the pilot; and he informed me that he would need more time to prepare for departure because he could not accept the new routing he had received. While this was going on; it became evident that due to a printer malfunction; we were not getting any arrival strips. Since many strips were missing; the coordinator; who would normally be standing between Local and Ground Control got busy hand writing arrival strips for most every arrival. I acknowledged Aircraft X and went back to what I had been doing. I scanned my runway and observed it to be clear. I then cleared Aircraft Z; who had been holding in position; for take off. Aircraft Z accepted the clearance and began take off roll. A few seconds later the AMASS/ASDE alerted 'Warning RWY XXR occupied'. I first thought it to be a false alert; since we get so very many of these but I immediately looked up at the display. I saw the Aircraft Z and the Aircraft Y icons flashing. I looked out the window and saw Aircraft Z on take off roll and Aircraft Y stopped at Taxiway Juliet; facing Runway XXR. I heard Ground Control telling Aircraft Y to hold short of Runway XXR. It appeared Aircraft Y was possibly across the runway hold short line; but short of the white runway edge line. I attempted to stop Aircraft Z's take off roll but it was too late. After the alert when off; I realized that the reason the runway had been clear when I scanned it was that for some unknown reason; Aircraft Y had delayed his runway crossing for so long; that my arrival aircraft had time to cross Runway XXR; clear on the other side. I also had answered Aircraft X's transmission about his routing. In the meantime; for some unknown reason Aircraft Y had not even begun his runway crossing even though he was instructed to do so immediately after the departing heavy jet had rolled through the intersection. I believe this delay was 'The setup' for this error when combined with the other factors. I normally use good runway safety technique. I do in fact I have a technique in place to prevent a runway crossing error. Any time I am crossing a runway with an aircraft down field and have an departure in position; I turn the departing aircraft's flight progress strip over face down on the counter so that I cannot see the call sign and therefore; cannot clear the aircraft for take off. Before I clear any aircraft for take off; I scan the runway physically; and then scan the AMASS/ASDE display to back up the visual scan. During this session the distractions of stopped aircraft; re-routing; missing strips and ground control's unusual request to cross Runway XXR were distracting enough that I neglected to turn Aircraft Z's flight strip over face down on the counter; as well as look up and do my usual back-up scan of the AMASS/ASDE. Normally; the coordinator would also have been a part of the process and been an extra set of eyes and ears; but he was not available due to the fact that he was writing arrival strips. Recommendation; I have been working at ZZZ for almost many years in it's current configuration. I very clearly remember how the ZZZ ATCT was configured when the new tower was first commissioned. The AMASS/ASDE displays were set on the counter. I believed this was the ideal setup. Having the AMASS display on the counter meant it fell more naturally in view when scanning the runways out the window. A few months later; due to the fact that the ASDE displays were hung from the ceiling in the old tower and most of the FPL's were used to having them there; the decision was made to alter the configuration and hang the displays. This current configuration now requires the Local Controller to look up and opposite the direction of departure traffic when on Runway XX. Had I scanned the AMASS/ASDE display; it is likely I would have seen Aircraft Y's Data Block at Taxiway Juliet and not cleared Aircraft Z for take off. If the display was on the counter; perhaps even with the other distractions present; I would have been more successful in keeping that in my scan. I don't expect that any tower configuration changes to take place based on this event. I know how difficult that can be. We are working in a busy; complex environment. I do believe minimizing distractions will go a long way towards preventing runway incursions. As with most errors; there were multiple factors mentioned that contributed to the final event. Any event that is 'out of the ordinary' is known to be a contributing cause towards operational errors. In this case; the Ground Controller's request to cross Runway XXR at Taxiway Juliet was a request that was out of the ordinary for me in this operational configuration. In the future; in addition to turning the flight progress strip face down; I intend to place a plastic flight strip holder on top of the strip whenever another control position is crossing a runway under my control and I have an aircraft in position. I also believe that if Aircraft Y had been on my Local Control frequency and I had cleared him across Runway XXR; 1; He would have been 'Top of mind' and not as easily overlooked as he delayed on Taxiway Juliet. 2; Aircraft Y would have heard the take off clearance for Aircraft Z as well as Aircraft Z hearing the clearance for Aircraft Y to cross Runway XXR. That being the case; I would make the recommendation that an aircraft that is going to cross a main departure/arrival runway and stay on taxiways under Local Control's control be on Local Control's frequency.

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.