Light transport overshot altitude intended by ARTCC during descent.

Attributes
ACN	90293
Time
Date	198807
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : fim
State Reference	CA
Altitude	msl bound lower : 26000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla
Operator	general aviation : corporate
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 120 flight time total : 6000 flight time type : 290
ASRS Report	90293
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

We were cleared from FL350 to FL330 which was acknowledged by copilot. After clearance given controller advised 'maintain 2-5-0 for sep.' copilot thought center meant FL250 and acknowledged, 'roger maintain 250.' captain's (my) attention was diverted at time of last broadcast and upon returning my attention I noticed 250 in altitude select. I questioned copilot who was sure we were cleared to FL250. Our policy is to resolve crew questions with verification from ATC. We were going to call ATC when ATC called us and said we were cleared to FL290. We were going through FL290 and advised him we were cleared to FL250. He said, 'roger, cleared to 250.' problem could have been corrected by making standard calls, such as 'maintain airspeed 250,' or give us 'maintain 250 KTS, maintain FL330.' our perception was that as we were close to fillmore VOR we would get a quick descent to cross tandy at 14000'. Our crew will mutually understand and acknowledge altitude changes in the future. All crew callbacks to ATC will confirm either KTS or altitude with the speed or flight level.

Original NASA ASRS Text

Title: LTT OVERSHOT ALT INTENDED BY ARTCC DURING DESCENT.

Narrative: WE WERE CLRED FROM FL350 TO FL330 WHICH WAS ACKNOWLEDGED BY COPLT. AFTER CLRNC GIVEN CTLR ADVISED 'MAINTAIN 2-5-0 FOR SEP.' COPLT THOUGHT CENTER MEANT FL250 AND ACKNOWLEDGED, 'ROGER MAINTAIN 250.' CAPT'S (MY) ATTN WAS DIVERTED AT TIME OF LAST BROADCAST AND UPON RETURNING MY ATTN I NOTICED 250 IN ALT SELECT. I QUESTIONED COPLT WHO WAS SURE WE WERE CLRED TO FL250. OUR POLICY IS TO RESOLVE CREW QUESTIONS WITH VERIFICATION FROM ATC. WE WERE GOING TO CALL ATC WHEN ATC CALLED US AND SAID WE WERE CLRED TO FL290. WE WERE GOING THROUGH FL290 AND ADVISED HIM WE WERE CLRED TO FL250. HE SAID, 'ROGER, CLRED TO 250.' PROB COULD HAVE BEEN CORRECTED BY MAKING STANDARD CALLS, SUCH AS 'MAINTAIN AIRSPD 250,' OR GIVE US 'MAINTAIN 250 KTS, MAINTAIN FL330.' OUR PERCEPTION WAS THAT AS WE WERE CLOSE TO FILLMORE VOR WE WOULD GET A QUICK DSCNT TO CROSS TANDY AT 14000'. OUR CREW WILL MUTUALLY UNDERSTAND AND ACKNOWLEDGE ALT CHANGES IN THE FUTURE. ALL CREW CALLBACKS TO ATC WILL CONFIRM EITHER KTS OR ALT WITH THE SPD OR FLT LEVEL.

Data retrieved from NASA's ASRS site as of August 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.