Narrative:

During initial descent into cle, we were assigned FL240, then reclred to FL250. After leveloff we were again cleared to FL240 (FL230?). Approaching FL240 I called: FL240 for FL230 which was in the altitude alert window. The first officer said: I think it should be FL240. We started to confirm with center as we passed FL240 and center called saying that we should level at FL240, and then said: level at your present altitude. We leveled at FL233. After leveling, we were reclred to continue descent with no apparent conflict. Analysis: I'm in the habit of stating new altitude and pointing to the altitude alert window when changing numbers. The first officer was sure the clearance was to FL240, not FL230 but FL230 was in the window. As I pointed to the number I may have nudged the set knob or the knob may have 'bumped' to FL230 after initial setting. As best remembered we both acknowledged and said the initial clearance. I probably should have hit altitude hold at the first indication of doubt and we would have leveled around FL237. Note: there were no major distractions however we were getting ATIS and beginning to brief the approach into cle. Supplemental information from acn 387116: I heard the captain state 'FL240 for FL230' to which I replied 'I thought we were cleared to FL240.' at that point center stated that they showed us going through FL240 which prompted the captain to start an immediate leveloff. Center then told us to level off where we were for the time being. Subsequently center cleared us to FL230. We ended up leveling at approximately FL233 by the time center told us to level off, then went down to FL230 when cleared. We had no major distractions of note: the only other activity was getting ATIS and beginning to brief the approach.

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Original NASA ASRS Text

Title: AN MD88 DSNDING IN ZOB, OH, AIRSPACE OVERSHOT ASSIGNED ALT DUE TO CONFUSION OF CLRED ALT.

Narrative: DURING INITIAL DSCNT INTO CLE, WE WERE ASSIGNED FL240, THEN RECLRED TO FL250. AFTER LEVELOFF WE WERE AGAIN CLRED TO FL240 (FL230?). APCHING FL240 I CALLED: FL240 FOR FL230 WHICH WAS IN THE ALT ALERT WINDOW. THE FO SAID: I THINK IT SHOULD BE FL240. WE STARTED TO CONFIRM WITH CTR AS WE PASSED FL240 AND CTR CALLED SAYING THAT WE SHOULD LEVEL AT FL240, AND THEN SAID: LEVEL AT YOUR PRESENT ALT. WE LEVELED AT FL233. AFTER LEVELING, WE WERE RECLRED TO CONTINUE DSCNT WITH NO APPARENT CONFLICT. ANALYSIS: I'M IN THE HABIT OF STATING NEW ALT AND POINTING TO THE ALT ALERT WINDOW WHEN CHANGING NUMBERS. THE FO WAS SURE THE CLRNC WAS TO FL240, NOT FL230 BUT FL230 WAS IN THE WINDOW. AS I POINTED TO THE NUMBER I MAY HAVE NUDGED THE SET KNOB OR THE KNOB MAY HAVE 'BUMPED' TO FL230 AFTER INITIAL SETTING. AS BEST REMEMBERED WE BOTH ACKNOWLEDGED AND SAID THE INITIAL CLRNC. I PROBABLY SHOULD HAVE HIT ALT HOLD AT THE FIRST INDICATION OF DOUBT AND WE WOULD HAVE LEVELED AROUND FL237. NOTE: THERE WERE NO MAJOR DISTRACTIONS HOWEVER WE WERE GETTING ATIS AND BEGINNING TO BRIEF THE APCH INTO CLE. SUPPLEMENTAL INFO FROM ACN 387116: I HEARD THE CAPT STATE 'FL240 FOR FL230' TO WHICH I REPLIED 'I THOUGHT WE WERE CLRED TO FL240.' AT THAT POINT CTR STATED THAT THEY SHOWED US GOING THROUGH FL240 WHICH PROMPTED THE CAPT TO START AN IMMEDIATE LEVELOFF. CTR THEN TOLD US TO LEVEL OFF WHERE WE WERE FOR THE TIME BEING. SUBSEQUENTLY CTR CLRED US TO FL230. WE ENDED UP LEVELING AT APPROX FL233 BY THE TIME CTR TOLD US TO LEVEL OFF, THEN WENT DOWN TO FL230 WHEN CLRED. WE HAD NO MAJOR DISTRACTIONS OF NOTE: THE ONLY OTHER ACTIVITY WAS GETTING ATIS AND BEGINNING TO BRIEF THE APCH.

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.