Narrative:

During the takeoff roll on runway 21C at dtw, we saw what appeared to be an aircraft crossing our runway somewhere downfield. While we were still below 80 KTS, the aircraft appeared to be clear of the runway, so I decided it was safe to continue the takeoff, but was concerned that a potential conflict had occurred on the runway. Upon arrival at denver I contacted dtw tower chief and he advised me that the only aircraft in the area was a DC10 taxiing wbound on taxiway T. Since taxiway T elevation is at 60 ft higher than the end of runway 21C, I believe what we saw was this aircraft on taxiway T, but it had the illusion of crossing our runway. Dtw tower chief advised me that there had been at least 4 unnecessary aborts on runway 21C due to this illusion problem. He said he would recommend an operations change at dtw tower to advise flts departing runway 21C when there is an aircraft taxiing on taxiway T. This would prevent any future aborts when there really is no traffic conflict. I am sure that the dtw regulars are already aware of this illusion on runway 21C, but operators who do not use dtw often should be advised of the potential for the illusion of traffic conflict at night when departing runway 21C.

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Original NASA ASRS Text

Title: A DEP B727-200 PIC ALMOST ABORTS THE TKOF FROM DTW RWY 21C WHEN A DC10 IS THOUGHT TO BE SEEN XING THE RWY SOME DISTANCE IN FRONT OF THE B727. PIC SAYS IT WAS ALL AN ILLUSION DURING THIS NIGHT TKOF.

Narrative: DURING THE TKOF ROLL ON RWY 21C AT DTW, WE SAW WHAT APPEARED TO BE AN ACFT XING OUR RWY SOMEWHERE DOWNFIELD. WHILE WE WERE STILL BELOW 80 KTS, THE ACFT APPEARED TO BE CLR OF THE RWY, SO I DECIDED IT WAS SAFE TO CONTINUE THE TKOF, BUT WAS CONCERNED THAT A POTENTIAL CONFLICT HAD OCCURRED ON THE RWY. UPON ARR AT DENVER I CONTACTED DTW TWR CHIEF AND HE ADVISED ME THAT THE ONLY ACFT IN THE AREA WAS A DC10 TAXIING WBOUND ON TXWY T. SINCE TXWY T ELEVATION IS AT 60 FT HIGHER THAN THE END OF RWY 21C, I BELIEVE WHAT WE SAW WAS THIS ACFT ON TXWY T, BUT IT HAD THE ILLUSION OF XING OUR RWY. DTW TWR CHIEF ADVISED ME THAT THERE HAD BEEN AT LEAST 4 UNNECESSARY ABORTS ON RWY 21C DUE TO THIS ILLUSION PROB. HE SAID HE WOULD RECOMMEND AN OPS CHANGE AT DTW TWR TO ADVISE FLTS DEPARTING RWY 21C WHEN THERE IS AN ACFT TAXIING ON TXWY T. THIS WOULD PREVENT ANY FUTURE ABORTS WHEN THERE REALLY IS NO TFC CONFLICT. I AM SURE THAT THE DTW REGULARS ARE ALREADY AWARE OF THIS ILLUSION ON RWY 21C, BUT OPERATORS WHO DO NOT USE DTW OFTEN SHOULD BE ADVISED OF THE POTENTIAL FOR THE ILLUSION OF TFC CONFLICT AT NIGHT WHEN DEPARTING RWY 21C.

Data retrieved from NASA's ASRS site as of July 2007 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.