Narrative:

On flight from bwi-ind, we had stepped down several times from our initial cruise altitude of FL350 to find a smooth altitude--finally at FL260. While at FL260, and while working with ZID, we were cleared to FL230, and to descend so as to be at a point 10 mi east of clang intersection at 11000' and a speed of 250 KTS. I set 11000' in the altitude reminder, and the captain confirmed 11000'. Descending out of FL230 to meet the restriction of 10 mi east of clang, we were issued a rather lengthy instruction that included an expect clearance to cross at clang intersection at 11000' and 250 KTS, and 11000' remained in the altitude reminder as we continued to comply with our actual clearance previously issued (10 mi east of clang). We continued the descent rate so as to meet the restriction 10 mi east of clang intersection. A comment was made by the controller referencing traffic at 16000' off to our 2 O'clock position, but emphasis was made by the controller that the clearance of 11000' and 250 KTS over clang was an, 'expect only.' again we continued our attempt to comply with the previous and more restrictive clearance 10 mi east of clang. Both the captain and I are qualified on TCAS. I had tested it on the ground before departing bwi. It was on and fully operational at the time. Passing about 16500', the controller asked us our altitude, which we gave him, and he then indicated there was a possible conflict with traffic, and we should have stopped our descent at 17000'. He did not ask us to stop our descent, nor increase or decrease the descent rate, nor turn to avoid a possible conflict, and did not restrict our continued descent to 11000'. At no time did I see the 16000' traffic depicted on TCAS, and at no time did we receive any visibility indication or aural warning concerning this traffic.

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Original NASA ASRS Text

Title: CTLR IMPLIED A TRAFFIC CONFLICT AND FLT CREW HAD MISINTERPRETED THEIR EXPECT CROSSING AT AS A FIRM CROSSING.

Narrative: ON FLT FROM BWI-IND, WE HAD STEPPED DOWN SEVERAL TIMES FROM OUR INITIAL CRUISE ALT OF FL350 TO FIND A SMOOTH ALT--FINALLY AT FL260. WHILE AT FL260, AND WHILE WORKING WITH ZID, WE WERE CLRED TO FL230, AND TO DSND SO AS TO BE AT A POINT 10 MI E OF CLANG INTXN AT 11000' AND A SPD OF 250 KTS. I SET 11000' IN THE ALT REMINDER, AND THE CAPT CONFIRMED 11000'. DSNDING OUT OF FL230 TO MEET THE RESTRICTION OF 10 MI E OF CLANG, WE WERE ISSUED A RATHER LENGTHY INSTRUCTION THAT INCLUDED AN EXPECT CLRNC TO CROSS AT CLANG INTXN AT 11000' AND 250 KTS, AND 11000' REMAINED IN THE ALT REMINDER AS WE CONTINUED TO COMPLY WITH OUR ACTUAL CLRNC PREVIOUSLY ISSUED (10 MI E OF CLANG). WE CONTINUED THE DSNT RATE SO AS TO MEET THE RESTRICTION 10 MI E OF CLANG INTXN. A COMMENT WAS MADE BY THE CTLR REFERENCING TFC AT 16000' OFF TO OUR 2 O'CLOCK POS, BUT EMPHASIS WAS MADE BY THE CTLR THAT THE CLRNC OF 11000' AND 250 KTS OVER CLANG WAS AN, 'EXPECT ONLY.' AGAIN WE CONTINUED OUR ATTEMPT TO COMPLY WITH THE PREVIOUS AND MORE RESTRICTIVE CLRNC 10 MI E OF CLANG. BOTH THE CAPT AND I ARE QUALIFIED ON TCAS. I HAD TESTED IT ON THE GND BEFORE DEPARTING BWI. IT WAS ON AND FULLY OPERATIONAL AT THE TIME. PASSING ABOUT 16500', THE CTLR ASKED US OUR ALT, WHICH WE GAVE HIM, AND HE THEN INDICATED THERE WAS A POSSIBLE CONFLICT WITH TFC, AND WE SHOULD HAVE STOPPED OUR DSNT AT 17000'. HE DID NOT ASK US TO STOP OUR DSNT, NOR INCREASE OR DECREASE THE DSNT RATE, NOR TURN TO AVOID A POSSIBLE CONFLICT, AND DID NOT RESTRICT OUR CONTINUED DSNT TO 11000'. AT NO TIME DID I SEE THE 16000' TFC DEPICTED ON TCAS, AND AT NO TIME DID WE RECEIVE ANY VIS INDICATION OR AURAL WARNING CONCERNING THIS TFC.

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.