Narrative:

After landing and during rollout on runway 22L; while thrust reversers were deployed at detent 2 (approximately speed 120 IAS decelerating); ATC informed us in a shaky voice; 'company number...I am (in apparent disbelief) getting an indication there is another aircraft on your runway!' the pm (first officer) immediately acknowledged the call; and I as PF (captain); began evasive action of bringing the aircraft to a complete stop while visually searching the runway environment for an intruding aircraft. Once my aircraft was stopped on the runway (just prior to intersecting runway 9L); we informed the tower controller of our position; and he replied; 'the target is idented to be behind you now.' event over. Taxied to gate. Terminating flight. The reporting of this event is solely as a result of ATC asde-X malfunction. The flight crew was not attributable to this incident. The dtw asde-X traffic management system surface movement radar and transponder multi-lateration sensors displayed a ghost aircraft position on an ATC tower display. These sensors malfunctioned and were not accurate or reliable for improving flight safety in my case. Although a false signal; we treated the information as a possible runway incursion at the time. The quality of the asde-X data resulted in the tower controller receiving his decision support. In our case; if the asde-X data was accurate; I would not be here to describe the event; however. Perhaps fixing this malfunction could avoid this occurrence from happening in the future.

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Original NASA ASRS Text

Title: ACR ON LNDG ROLL AT DTW RECEIVED ATC ASDE-X ALERT; INDICATING TFC ON THE RWY; FLT CREW ACCELERATED LNDG STOP; ATC ADVISED LIKELY FALSE TARGET EVENT.

Narrative: AFTER LNDG AND DURING ROLLOUT ON RWY 22L; WHILE THRUST REVERSERS WERE DEPLOYED AT DETENT 2 (APPROX SPD 120 IAS DECELERATING); ATC INFORMED US IN A SHAKY VOICE; 'COMPANY NUMBER...I AM (IN APPARENT DISBELIEF) GETTING AN INDICATION THERE IS ANOTHER ACFT ON YOUR RWY!' THE PM (FO) IMMEDIATELY ACKNOWLEDGED THE CALL; AND I AS PF (CAPT); BEGAN EVASIVE ACTION OF BRINGING THE ACFT TO A COMPLETE STOP WHILE VISUALLY SEARCHING THE RWY ENVIRONMENT FOR AN INTRUDING ACFT. ONCE MY ACFT WAS STOPPED ON THE RWY (JUST PRIOR TO INTERSECTING RWY 9L); WE INFORMED THE TWR CTLR OF OUR POS; AND HE REPLIED; 'THE TARGET IS IDENTED TO BE BEHIND YOU NOW.' EVENT OVER. TAXIED TO GATE. TERMINATING FLT. THE RPTING OF THIS EVENT IS SOLELY AS A RESULT OF ATC ASDE-X MALFUNCTION. THE FLT CREW WAS NOT ATTRIBUTABLE TO THIS INCIDENT. THE DTW ASDE-X TFC MGMNT SYS SURFACE MOVEMENT RADAR AND XPONDER MULTI-LATERATION SENSORS DISPLAYED A GHOST ACFT POS ON AN ATC TWR DISPLAY. THESE SENSORS MALFUNCTIONED AND WERE NOT ACCURATE OR RELIABLE FOR IMPROVING FLT SAFETY IN MY CASE. ALTHOUGH A FALSE SIGNAL; WE TREATED THE INFO AS A POSSIBLE RWY INCURSION AT THE TIME. THE QUALITY OF THE ASDE-X DATA RESULTED IN THE TWR CTLR RECEIVING HIS DECISION SUPPORT. IN OUR CASE; IF THE ASDE-X DATA WAS ACCURATE; I WOULD NOT BE HERE TO DESCRIBE THE EVENT; HOWEVER. PERHAPS FIXING THIS MALFUNCTION COULD AVOID THIS OCCURRENCE FROM HAPPENING IN THE FUTURE.

Data retrieved from NASA's ASRS site as of May 2009 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.