ALT DEV ALT OVERSHOT DURING A MEDICAL EMER WITH ILL PAX.

Narrative

FLT ORIGINATED IN LONG BEACH; CA; NON STOP TO SAN FRANCISCO. WE WERE CLRED TO BIG SUR; BIG SUR PROFILE RTE ONLY MAINTAIN FL310. SHORTLY BEFORE REACHING BIG SUR A PAX BECAME SERIOUSLY ILL AND NEEDED MEDICAL ATTN QUICKLY. THE CAPT REQUESTED PRIORITY RTING TO SFO AND DECLARED A MEDICAL EMER. CENTER INSTRUCTED US DIRECT TO SFO AND DSND TO 11000 FT. THE BOTH OF US WERE QUITE BUSY COORDINATING BTWN THE CABIN CREW ASSISTING THE ILL PAX; COMPANY COM AND PLANNING THE APCH AT SFO; WHEN THE CAPT; WHO WAS THE PF; DSNDED TO 10600 FT BEFORE CORRECTING BACK TO 11000 FT. THE REASON HE INADVERTENTLY DSNDED BELOW 11000 FT WAS BECAUSE WITH ALL THE ACTIVITY IN THE CABIN AND TRYING TO FLY THE ACFT BY HAND; WE BOTH DIDN'T CATCH THE ALT UNTIL 10600 FT. I; PNF; TOLD APCH THAT WE WERE CORRECTING BACK TO 11000 FT; AND I DON'T BELIEVE THERE WAS ANY CONFLICTING TFC. THE FLT PROCEEDED TO SFO WITHOUT FURTHER INCIDENT. THERE IS ALWAYS SOMETHING TO LEARN THROUGH MISTAKES; AND I THINK LEAVING THE ACFT ON AUTOPLT IN TIMES OF IRREGULAR OPS OR PROCS IS THE BEST WAY TO PROTECT AGAINST COMPOUNDING THE PROBLEM.