Narrative:

Contacted center and declared medical emergency on board and requested immediate descent for landing at chs. Center cleared us to FL240 (from FL330) then to FL230. I immediately initiated at flight idle descent. The flight attendant then came to the flight deck for the emergency medical kit which is located behind my seat (first officer seat). She couldn't release the kit and needed assistance. Control of the aircraft was then positively switched to the captain while I helped the flight attendant. The kit was released, the flight attendant exited the flight deck and I was then given control of the aircraft, still in the descent to FL230. The autoplt was engaged. However, I was unaware that the captain extended the speed brakes. The autoplt initiated a slow rate of level off which did not successfully 'catch' the programmed flight level of FL230. I disengaged the autoplt at approximately 200 ft low (22800 ft) and excess nose down trim continued the aircraft to 22500 ft at which time a climb began back to FL230. 500 ft was the extend of the overshoot and the entire deviation lasted approximately 10-15 seconds (from FL230 back to FL230). After leveloff the captain pointed out the speed brakes and they were retracted. Nothing of the deviation was mentioned by center. The subsequent descent and landing was uneventful. Supplemental information from acn 272913: however, that item slipped by calling a deviation of 500 ft. Next time I will tell first officer if speed brake is out when transferring aircraft control. Overall we were very pleased with the rapid descent/diversion.

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Original NASA ASRS Text

Title: ACR HAS ALTDEV OF 500 FT DURING EMER DSCNT.

Narrative: CONTACTED CTR AND DECLARED MEDICAL EMER ON BOARD AND REQUESTED IMMEDIATE DSCNT FOR LNDG AT CHS. CTR CLRED US TO FL240 (FROM FL330) THEN TO FL230. I IMMEDIATELY INITIATED AT FLT IDLE DSCNT. THE FLT ATTENDANT THEN CAME TO THE FLT DECK FOR THE EMER MEDICAL KIT WHICH IS LOCATED BEHIND MY SEAT (FO SEAT). SHE COULDN'T RELEASE THE KIT AND NEEDED ASSISTANCE. CTL OF THE ACFT WAS THEN POSITIVELY SWITCHED TO THE CAPT WHILE I HELPED THE FLT ATTENDANT. THE KIT WAS RELEASED, THE FLT ATTENDANT EXITED THE FLT DECK AND I WAS THEN GIVEN CTL OF THE ACFT, STILL IN THE DSCNT TO FL230. THE AUTOPLT WAS ENGAGED. HOWEVER, I WAS UNAWARE THAT THE CAPT EXTENDED THE SPD BRAKES. THE AUTOPLT INITIATED A SLOW RATE OF LEVEL OFF WHICH DID NOT SUCCESSFULLY 'CATCH' THE PROGRAMMED FLT LEVEL OF FL230. I DISENGAGED THE AUTOPLT AT APPROX 200 FT LOW (22800 FT) AND EXCESS NOSE DOWN TRIM CONTINUED THE ACFT TO 22500 FT AT WHICH TIME A CLB BEGAN BACK TO FL230. 500 FT WAS THE EXTEND OF THE OVERSHOOT AND THE ENTIRE DEV LASTED APPROX 10-15 SECONDS (FROM FL230 BACK TO FL230). AFTER LEVELOFF THE CAPT POINTED OUT THE SPD BRAKES AND THEY WERE RETRACTED. NOTHING OF THE DEV WAS MENTIONED BY CTR. THE SUBSEQUENT DSCNT AND LNDG WAS UNEVENTFUL. SUPPLEMENTAL INFO FROM ACN 272913: HOWEVER, THAT ITEM SLIPPED BY CALLING A DEV OF 500 FT. NEXT TIME I WILL TELL FO IF SPD BRAKE IS OUT WHEN TRANSFERRING ACFT CTL. OVERALL WE WERE VERY PLEASED WITH THE RAPID DSCNT/DIVERSION.

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.