Narrative:

Upon intercepting dtw runway 21R localizer at approximately 10-12 mi out at 4000 ft MSL, aircraft Y observed a cessna, aircraft #2, at 12:30 O'clock position at approximately 4200 ft and 1/2 mi. Our heading was approximately 215 degrees on the localizer and the cessna crossed right to left (heading about 125 degrees). The aircraft appeared level until it got to our 11 O'clock position, where it began a descent. The cessna crossed through our altitude (4000 ft) at our 10 O'clock position at 1/4 - 1/2 mi. I was PF and took no evasive action. There was no TCASII alert, and approach control only had a primary target. Reminder: keep looking outside.

Google
 

Original NASA ASRS Text

Title: ACR B737 PIC OBSERVES SMA CESSNA PASS WITHIN ONE HALF MI IN FRONT OF HIS ACFT WHILE DSNDING INBOUND ON THE ILS APCH TO DTW RWY 21R. PIC TOOK NO EVASIVE ACTION. PIC RPTS NO TCASII ALERT AND THAT APCH CTL ADVISED ONLY A PRIMARY TARGET WAS OBSERVED.

Narrative: UPON INTERCEPTING DTW RWY 21R LOC AT APPROX 10-12 MI OUT AT 4000 FT MSL, ACFT Y OBSERVED A CESSNA, ACFT #2, AT 12:30 O'CLOCK POS AT APPROX 4200 FT AND 1/2 MI. OUR HDG WAS APPROX 215 DEGS ON THE LOC AND THE CESSNA CROSSED R TO L (HDG ABOUT 125 DEGS). THE ACFT APPEARED LEVEL UNTIL IT GOT TO OUR 11 O'CLOCK POS, WHERE IT BEGAN A DSCNT. THE CESSNA CROSSED THROUGH OUR ALT (4000 FT) AT OUR 10 O'CLOCK POS AT 1/4 - 1/2 MI. I WAS PF AND TOOK NO EVASIVE ACTION. THERE WAS NO TCASII ALERT, AND APCH CTL ONLY HAD A PRIMARY TARGET. REMINDER: KEEP LOOKING OUTSIDE.

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.