A phl controller issued a very late go around in response to an asde-X alarm. The reporter noted the...

Narrative:

I was working local east and had a crj cleared to land on runway 26. Right before the aircraft touched down on the runway; the asde-X alarm went off and said to 'go around runway 26'. I saw a couple of targets on the taxiways holding short of runway 26 but I did not see anything on the actual runway. As required; I instructed the crj to go around and gave him further instructions. I received no response from the aircraft and so I again instructed the aircraft to go around 'if able'. This time the aircraft responded and went around. I am not sure why the system alarm on the asde-X went off; but it was determined that there was not a vehicle on the runway. It may have been a reflection or a false target response. Either way; the aircraft was literally about to touch down on the runway and was in a critical phase of flight. Sending the aircraft around at this point in time may have been more unsafe then letting him land but as required by the asde-X; I have to send aircraft around when the alarm indicates to do so. I would just recommend further investigation on the asde-X and false targets. Maybe we can figure out what causes this to happen in order to prevent it from occurring again.

Original NASA ASRS Text

Title: A PHL Controller issued a very late go around in response to an ASDE-X Alarm. The reporter noted the go around may have been unsafe and not needed but mandated by ATC rules.

Narrative: I was working Local East and had a CRJ cleared to land on Runway 26. Right before the aircraft touched down on the runway; the ASDE-X alarm went off and said to 'GO Around Runway 26'. I saw a couple of targets on the taxiways holding short of Runway 26 but I did not see anything on the actual runway. As required; I instructed the CRJ to Go Around and gave him further instructions. I received no response from the aircraft and so I again instructed the aircraft to Go Around 'if able'. This time the aircraft responded and went around. I am not sure why the system alarm on the ASDE-X went off; but it was determined that there was not a vehicle on the runway. It may have been a reflection or a false target response. Either way; the aircraft was literally about to touch down on the runway and was in a critical phase of flight. Sending the aircraft around at this point in time may have been more unsafe then letting him land but as required by the ASDE-X; I have to send aircraft around when the alarm indicates to do so. I would just recommend further investigation on the ASDE-X and false targets. Maybe we can figure out what causes this to happen in order to prevent it from occurring again.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1031658
Time
Date	201208
Local Time Of Day	1801-2400
Place
Locale Reference	PHL.Airport
State Reference	PA
Aircraft 1
Make Model Name	Regional Jet 200 ER/LR (CRJ200)
Operating Under FAR Part	Part 121
Flight Phase	Landing
Route In Use	Visual Approach
Flight Plan	IFR
Person 1
Function	Local
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types

A phl controller issued a very late go around in response to an asde-X alarm. The reporter noted the go around may have been unsafe and not needed but mandated by ATC rules.