Narrative:

I cleared aircraft X for takeoff on runway 4L. Car X (operations vehicle) was holding short of runway 4L on runway 29 awaiting to cross. Aircraft X was airborne and in the turn to join the newark 2 departure. The asde X alerted that aircraft X and car X were converging. The supervisor along with the cab coordinator both observed aircraft X approximately 400 feet and turning to join the newark 2 when the asde generated the alert.the replay with the audio is off and does not give an accurate description of what actually went on out the window. Aircraft X was airborne and in the turn when the crossing instruction was issued. Both myself and the cab coordinator said out loud 'he's above him' (approximately 400 feet) when the alert was generated. How did that generate an alert? The supervisor observed the same. The replay makes it look like I said for the car to cross runway 4L before aircraft X was airborne and turning; which is not true and observed by all of the above. The altitude read out from the replay is invalid.on the replay it shows aircraft X at 000 feet as I said to contact departure because the audio is out of sync. Instructing aircraft to contact departure before rotation speed is a dangerous practice. I was not afforded to see the actual asde radar dump. The replay shows no bars and does not show a true time line of what was said at the exact point. The asde integrity at ewr has been scrutinized over and over relative to this exact matter. I have seen many times that the safety bars will lag as the system needs to catch up. The bars will still be up near the departure end as the aircraft is well off the departure end and turning. This will not happen with every aircraft; but still occurs. The asde needs to be logged of service due to all events in question that do not portray what really happened out the window.the human eye is more powerful than a computer. Especially to an asde that is always been scrutinized at ewr. So far this event has been put into a category of a loss of separation/runway incursion. Taking data from a computer that is not synced properly with the audio; showing invalid altitude readouts; and an asde that has been wrong in the past; and not the account of the local controller; cab coordinator; and supervisor of what the human eye saw out the window; is in my opinion an improper investigation.

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Original NASA ASRS Text

Title: A Tower Local Controller reported the ASDE-X alerted on traffic that was already airborne and past a vehicle holding short of the runway.

Narrative: I cleared aircraft X for takeoff on Runway 4L. Car X (Operations vehicle) was holding short of Runway 4L on Runway 29 awaiting to cross. Aircraft X was airborne and in the turn to join the Newark 2 departure. The ASDE X alerted that aircraft X and Car X were converging. The Supervisor along with the Cab Coordinator both observed aircraft X approximately 400 feet and turning to join the Newark 2 when the ASDE generated the alert.The replay with the audio is off and does not give an accurate description of what actually went on out the window. Aircraft X was airborne and in the turn when the crossing instruction was issued. Both myself and the Cab Coordinator said out loud 'he's above him' (approximately 400 feet) when the alert was generated. How did that generate an alert? The Supervisor observed the same. The replay makes it look like I said for the car to cross Runway 4L before aircraft X was airborne and turning; which is not true and observed by all of the above. The altitude read out from the replay is invalid.On the replay it shows aircraft X at 000 feet as I said to contact Departure because the audio is out of sync. Instructing aircraft to contact Departure before rotation speed is a dangerous practice. I was not afforded to see the actual ASDE radar dump. The replay shows no bars and does not show a true time line of what was said at the exact point. The ASDE integrity at EWR has been scrutinized over and over relative to this exact matter. I have seen many times that the safety bars will lag as the system needs to catch up. The bars will still be up near the departure end as the aircraft is well off the departure end and turning. This will not happen with every aircraft; but still occurs. The ASDE needs to be logged of service due to all events in question that do not portray what really happened out the window.The human eye is more powerful than a computer. Especially to an ASDE that is always been scrutinized at EWR. So far this event has been put into a category of a loss of separation/runway incursion. Taking data from a computer that is not synced properly with the audio; showing invalid altitude readouts; and an ASDE that has been wrong in the past; and not the account of the Local Controller; Cab Coordinator; and Supervisor of what the human eye saw out the window; is in my opinion an improper investigation.

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.