Narrative:

A B737 was an arrival aircraft that was cleared to cross departure runway 9L. I observed the aircraft visually clear the runway. I also observed the aircraft clear the runway on the asde display. A B767 was cleared for takeoff on runway 9L about a minute and a half later. The B737 subsequently advised ground control that he thought he might not be clear of the runway. The B737 showed clear of the runway. The ground controller told me and I estimated that due to the B767 being at approximately taxiway tango that he was not at V1 and it was safe to abort him. I told him to abort and he acknowledged. The asde stop bars were up and no alarm sounded. Not less than two seconds later; the B737 advised that he was clear. The voice tape and asde playback were both reviewed. Based on this information alone; an operational error was filed. I do not believe there is definitive proof of the error. The B737 aircraft can not see his aircraft tail and has no idea whether or not it is clear of the runway or the hold short lines. I know that we do not have the tools necessary to safely determine if aircraft are clear of the hold short lines at intersections as none of them are depicted. They are not standard either as there are multiple lines depicted differently around the airport. Yet this is at least the second time I know of that we have been charged an operational error due to this type of situation. Furthermore; the asde is a digital; estimated approximation of the aircraft location. There are computer icons for aircraft. Many times these icons face 180 degrees opposite of the direction the aircraft actually is. The asde is not totally reliable information. The same icons are used for this B737 as would be used for a C152; yet they are vastly different aircraft. How can we know if aircraft are clear of the necessary hold short lines when those lines are not depicted and we have computer icons for all aircraft? In this particular incident; how is it a definitive error when an aircraft 'thinks' they may not be clear; yet two seconds later says they are clear or 'think' they are? Pilot's estimations are not definitive proof of errors or positive separation. We are the busiest airport in the world; yet we need improvements to the asde at atl to safely do our job. All hold short lines need to be depicted on the asde airport map. More than two different icons need to be used for the vastly different aircraft sizes; if we have to continue having icons due to asde's design. Raw primary data would be much better; but I'm assuming we are going to be forced to continue with the digital approximation.

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Original NASA ASRS Text

Title: ATL Controller described canceling a take off clearance after a landing aircraft expressed some uncertainty regarding runway clearance; the reporter noting ASDE and visual observation indicated the landing was clear.

Narrative: A B737 was an arrival aircraft that was cleared to cross departure Runway 9L. I observed the aircraft visually clear the runway. I also observed the aircraft clear the runway on the ASDE display. A B767 was cleared for takeoff on Runway 9L about a minute and a half later. The B737 subsequently advised Ground Control that he thought he might not be clear of the runway. The B737 showed clear of the runway. The Ground Controller told me and I estimated that due to the B767 being at approximately Taxiway Tango that he was not at V1 and it was safe to abort him. I told him to abort and he acknowledged. The ASDE stop bars were up and no alarm sounded. Not less than two seconds later; the B737 advised that he was clear. The voice tape and ASDE playback were both reviewed. Based on this information alone; an Operational Error was filed. I do not believe there is definitive proof of the error. The B737 aircraft can not see his aircraft tail and has no idea whether or not it is clear of the runway or the hold short lines. I know that we do not have the tools necessary to safely determine if aircraft are clear of the hold short lines at intersections as none of them are depicted. They are not standard either as there are multiple lines depicted differently around the airport. Yet this is at least the second time I know of that we have been charged an Operational Error due to this type of situation. Furthermore; the ASDE is a digital; estimated approximation of the aircraft location. There are computer icons for aircraft. Many times these icons face 180 degrees opposite of the direction the aircraft actually is. The ASDE is not totally reliable information. The same icons are used for this B737 as would be used for a C152; yet they are vastly different aircraft. How can we know if aircraft are clear of the necessary hold short lines when those lines are not depicted and we have computer icons for all aircraft? In this particular incident; how is it a definitive error when an aircraft 'thinks' they may not be clear; yet two seconds later says they are clear or 'think' they are? Pilot's estimations are not definitive proof of errors or positive separation. We are the busiest airport in the world; yet we need improvements to the ASDE at ATL to safely do our job. All hold short lines need to be depicted on the ASDE airport map. More than two different icons need to be used for the vastly different aircraft sizes; if we have to continue having icons due to ASDE's design. RAW primary data would be much better; but I'm assuming we are going to be forced to continue with the digital approximation.

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.