Narrative:

ATC gave 'climb to FL230' clearance. FL230 was set in altitude selector. Aircraft was on autoplt and FMS. At approximately FL240 captain recognized aircraft was above preset altitude. He challenged copilot (who was at controls), 'what was assigned altitude?' at this point there was confusion as the last assigned altitude and if altitude was FL230 assigned, why did autoplt not leveloff at FL230. At this point ZID requested 'say altitude.' captain replied FL240 as aircraft was going through FL240. ZID commanded 'descend to FL230.' immediate descent was made. No incursion or effect on any other aircraft was made. No other aircraft in the area. Unknown why autoplt did not stop at preselect altitude. Pilots did not catch mistake by using SOP of calling 1000 ft and 300 ft prior to leveloff at assigned altitude. Did not use good situational awareness in that altitude was missed and there was confusion as to last assigned. Possibly too much psychological reliance on autoplt/FMS and lack of monitoring by PF and lack of challenge by PNF. Adherence to SOP would have created a redundancy that would have caught error. Aircraft's avionics are relatively new and had not had any prior problems in this area. Possibly contributing to a lack of vigilance in this area.

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Original NASA ASRS Text

Title: FLC OF A BRITISH HAWKER, HS25 OVERSHOT ASSIGNED ALT IN CLB DUE TO THE AUTOPLT FAILURE TO CAPTURE SET ALT AND THE ALT ALERTER TO PROVIDE AURAL WARNING.

Narrative: ATC GAVE 'CLB TO FL230' CLRNC. FL230 WAS SET IN ALT SELECTOR. ACFT WAS ON AUTOPLT AND FMS. AT APPROX FL240 CAPT RECOGNIZED ACFT WAS ABOVE PRESET ALT. HE CHALLENGED COPLT (WHO WAS AT CTLS), 'WHAT WAS ASSIGNED ALT?' AT THIS POINT THERE WAS CONFUSION AS THE LAST ASSIGNED ALT AND IF ALT WAS FL230 ASSIGNED, WHY DID AUTOPLT NOT LEVELOFF AT FL230. AT THIS POINT ZID REQUESTED 'SAY ALT.' CAPT REPLIED FL240 AS ACFT WAS GOING THROUGH FL240. ZID COMMANDED 'DSND TO FL230.' IMMEDIATE DSCNT WAS MADE. NO INCURSION OR EFFECT ON ANY OTHER ACFT WAS MADE. NO OTHER ACFT IN THE AREA. UNKNOWN WHY AUTOPLT DID NOT STOP AT PRESELECT ALT. PLTS DID NOT CATCH MISTAKE BY USING SOP OF CALLING 1000 FT AND 300 FT PRIOR TO LEVELOFF AT ASSIGNED ALT. DID NOT USE GOOD SITUATIONAL AWARENESS IN THAT ALT WAS MISSED AND THERE WAS CONFUSION AS TO LAST ASSIGNED. POSSIBLY TOO MUCH PSYCHOLOGICAL RELIANCE ON AUTOPLT/FMS AND LACK OF MONITORING BY PF AND LACK OF CHALLENGE BY PNF. ADHERENCE TO SOP WOULD HAVE CREATED A REDUNDANCY THAT WOULD HAVE CAUGHT ERROR. ACFT'S AVIONICS ARE RELATIVELY NEW AND HAD NOT HAD ANY PRIOR PROBS IN THIS AREA. POSSIBLY CONTRIBUTING TO A LACK OF VIGILANCE IN THIS AREA.

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.