Narrative:

Simul runway 9R and runway 9L approachs at ord. A B767 slowed before the OM. This is a violation of ATC instructions verified via radio with the pilot. A CRJ7 was gaining on the B767. I instructed the B767 to execute missed approach. Ord tower immediately countermanded my missed approach instructions and advised the B767 to continue. I then instructed the CRJ7 to execute missed approach due to insufficient wake turbulence separation. The B767 then advised ord tower that he could not land; most likely due to confusion in the cockpit; created by ord tower. The result was that ord tower now had 2 missed approachs. The B767 had to descend from 3400 ft on his way to 4000 ft; back down to 3000 ft; in order to stay below the CRJ7 that was already at 4000 ft on their missed approach. Ord tower; by countermanding my instructions; created an extremely unsafe situation and caused an unnecessary delay to the CRJ7. As a side note: I was working the parallel monitor position. My airspace begins at 22 mi and continues to 1 mi final. Once an aircraft is told to execute missed approach; it should not be changed. The parallel monitor has authority/authorized for airspace to 1 mi final.

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Original NASA ASRS Text

Title: C90 CTLR DESCRIBED INCIDENT WHEN BOTH ACFT ON SIMULTANEOUS APCHS TO RWY 9L AND RWY 9R WENT AROUND DUE TO AN INAPPROPRIATE TWR CLRNC.

Narrative: SIMUL RWY 9R AND RWY 9L APCHS AT ORD. A B767 SLOWED BEFORE THE OM. THIS IS A VIOLATION OF ATC INSTRUCTIONS VERIFIED VIA RADIO WITH THE PLT. A CRJ7 WAS GAINING ON THE B767. I INSTRUCTED THE B767 TO EXECUTE MISSED APCH. ORD TWR IMMEDIATELY COUNTERMANDED MY MISSED APCH INSTRUCTIONS AND ADVISED THE B767 TO CONTINUE. I THEN INSTRUCTED THE CRJ7 TO EXECUTE MISSED APCH DUE TO INSUFFICIENT WAKE TURB SEPARATION. THE B767 THEN ADVISED ORD TWR THAT HE COULD NOT LAND; MOST LIKELY DUE TO CONFUSION IN THE COCKPIT; CREATED BY ORD TWR. THE RESULT WAS THAT ORD TWR NOW HAD 2 MISSED APCHS. THE B767 HAD TO DSND FROM 3400 FT ON HIS WAY TO 4000 FT; BACK DOWN TO 3000 FT; IN ORDER TO STAY BELOW THE CRJ7 THAT WAS ALREADY AT 4000 FT ON THEIR MISSED APCH. ORD TWR; BY COUNTERMANDING MY INSTRUCTIONS; CREATED AN EXTREMELY UNSAFE SITUATION AND CAUSED AN UNNECESSARY DELAY TO THE CRJ7. AS A SIDE NOTE: I WAS WORKING THE PARALLEL MONITOR POS. MY AIRSPACE BEGINS AT 22 MI AND CONTINUES TO 1 MI FINAL. ONCE AN ACFT IS TOLD TO EXECUTE MISSED APCH; IT SHOULD NOT BE CHANGED. THE PARALLEL MONITOR HAS AUTH FOR AIRSPACE TO 1 MI FINAL.

Data retrieved from NASA's ASRS site as of January 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.