C560 pilot had an altitude overshoot.

Attributes
ACN	444660
Time
Date	199908
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : bil.airport
State Reference	MT
Altitude	msl bound lower : 23500 msl bound upper : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc.artcc
Operator	general aviation : corporate
Make Model Name	Citation V
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : single pilot
Qualification	pilot : multi engine pilot : cfi pilot : atp
Experience	flight time last 90 days : 40 flight time total : 14000 flight time type : 1000
ASRS Report	444660
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance controller : issued advisory flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I started my descent from FL410, 120 mi from billings. I was cleared down to FL390. I armed the altitude preselect on the flight director, and as I descended through FL392, center cleared me to FL240. I reset the preselect to FL240. On the honeywell flight director system, if the aircraft altitude preselect has armed but not captured the altitude, and if you change the preselector, it will not rearm automatically if the system is within 200 or 60 ft. I missed the fact that it wasn't armed for FL240. At the time, I was completing the descent checklist, and listening to bil ATIS information. When I looked up from writing down the ATIS, and working my v-spds for landing, I saw the altimeter descending through FL235. I quickly turned off the autoplt and returned to FL240. Center questioned me about my altitude I was supposed to stop at, and I informed him I was returning to FL240. He then cleared me to 16000 ft and to turn 15 degrees left. On the later altitude preselect system, the system will automatically rearm when you change the altitude, which is a much better system.

Original NASA ASRS Text

Title: C560 PLT HAD AN ALT OVERSHOOT.

Narrative: I STARTED MY DSCNT FROM FL410, 120 MI FROM BILLINGS. I WAS CLRED DOWN TO FL390. I ARMED THE ALT PRESELECT ON THE FLT DIRECTOR, AND AS I DSNDED THROUGH FL392, CTR CLRED ME TO FL240. I RESET THE PRESELECT TO FL240. ON THE HONEYWELL FLT DIRECTOR SYS, IF THE ACFT ALT PRESELECT HAS ARMED BUT NOT CAPTURED THE ALT, AND IF YOU CHANGE THE PRESELECTOR, IT WILL NOT REARM AUTOMATICALLY IF THE SYS IS WITHIN 200 OR 60 FT. I MISSED THE FACT THAT IT WASN'T ARMED FOR FL240. AT THE TIME, I WAS COMPLETING THE DSCNT CHKLIST, AND LISTENING TO BIL ATIS INFO. WHEN I LOOKED UP FROM WRITING DOWN THE ATIS, AND WORKING MY V-SPDS FOR LNDG, I SAW THE ALTIMETER DSNDING THROUGH FL235. I QUICKLY TURNED OFF THE AUTOPLT AND RETURNED TO FL240. CTR QUESTIONED ME ABOUT MY ALT I WAS SUPPOSED TO STOP AT, AND I INFORMED HIM I WAS RETURNING TO FL240. HE THEN CLRED ME TO 16000 FT AND TO TURN 15 DEGS L. ON THE LATER ALT PRESELECT SYS, THE SYS WILL AUTOMATICALLY REARM WHEN YOU CHANGE THE ALT, WHICH IS A MUCH BETTER SYS.

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.