Narrative:

Aircraft X checked on frequency and was climbed to FL230. Aircraft Y checked on 60-90 seconds later and was climbed to FL230. There was no known chop or WX in the immediate area. Previously, a number of aircraft had been worked without incident. An unexpected overtake situation occurred, and the aircraft were vectored with altitude restrs to ensure separation. When asked about speed, aircraft X indicated 250 KTS. This speed had not been assigned. Exclusive of other factors, controllers use standard performance values when separating aircraft. If pilots do not advise controllers when checking in when they are non-standard, then safety and traffic flow can be compromised.

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Original NASA ASRS Text

Title: ZID INSTRUCTOR CTLR IS REQUIRED TO TAKE ACTION TO ENSURE SEPARATION BTWN A CLBING E135 AND AN OVERTAKING B737, BOTH CLBING TO FL230 PASSING 16000 FT.

Narrative: ACFT X CHKED ON FREQ AND WAS CLBED TO FL230. ACFT Y CHKED ON 60-90 SECONDS LATER AND WAS CLBED TO FL230. THERE WAS NO KNOWN CHOP OR WX IN THE IMMEDIATE AREA. PREVIOUSLY, A NUMBER OF ACFT HAD BEEN WORKED WITHOUT INCIDENT. AN UNEXPECTED OVERTAKE SIT OCCURRED, AND THE ACFT WERE VECTORED WITH ALT RESTRS TO ENSURE SEPARATION. WHEN ASKED ABOUT SPD, ACFT X INDICATED 250 KTS. THIS SPD HAD NOT BEEN ASSIGNED. EXCLUSIVE OF OTHER FACTORS, CTLRS USE STANDARD PERFORMANCE VALUES WHEN SEPARATING ACFT. IF PLTS DO NOT ADVISE CTLRS WHEN CHKING IN WHEN THEY ARE NON-STANDARD, THEN SAFETY AND TFC FLOW CAN BE COMPROMISED.

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.