Flight crew misinterpreted clearance and deviated from assigned altitude.

Attributes
ACN	492360
Time
Date	200011
Day	Thu
Local Time Of Day	0601 To 1200
Place
State Reference	IN
Altitude	msl bound lower : 32200 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid.artcc
Operator	general aviation : corporate
Make Model Name	Challenger CL600
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 50 flight time total : 7600 flight time type : 150
ASRS Report	492360
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : commercial pilot : multi engine pilot : instrument
Experience	flight time last 90 days : 60 flight time total : 4600
ASRS Report	492137
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : company policies other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : returned to assigned altitude
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

ZID gave us a descent from FL370 to FL300 (that's what we read back) then a frequency change. Next controller was very busy, I reported out of FL335 for FL300. At FL322 they called back and said, we were only cleared to FL330. Controller gave us a turn to left 180 degrees and asked us to say altitude. We were at FL330. Controller said we have traffic at 7 mi and 2000 ft below us, and told us to go on course. (No TA's or RA's) we feel we have a big gap in our 'CRM.' we just came from a very busy airport around new york. Once we got into a familiar area we got complacent. Both of us missed that FL300 was wrong. Supplemental information from acn 492137: we always have the PNF work the radios. The PF always sets the heading bug and verifies inputs to the FMS, however, the PNF is the sole manipulator of the altitude selector knob. This fact points out that if the PNF makes an error in selection, the PF may not catch it. Check and balance is gone. Also, for this particular case it should have been obvious to us that an error on our part was made (because of the fact that FL300 is not used).

Original NASA ASRS Text

Title: FLC MISINTERPRETED CLRNC AND DEVIATED FROM ASSIGNED ALT.

Narrative: ZID GAVE US A DSCNT FROM FL370 TO FL300 (THAT'S WHAT WE READ BACK) THEN A FREQ CHANGE. NEXT CTLR WAS VERY BUSY, I RPTED OUT OF FL335 FOR FL300. AT FL322 THEY CALLED BACK AND SAID, WE WERE ONLY CLRED TO FL330. CTLR GAVE US A TURN TO L 180 DEGS AND ASKED US TO SAY ALT. WE WERE AT FL330. CTLR SAID WE HAVE TFC AT 7 MI AND 2000 FT BELOW US, AND TOLD US TO GO ON COURSE. (NO TA'S OR RA'S) WE FEEL WE HAVE A BIG GAP IN OUR 'CRM.' WE JUST CAME FROM A VERY BUSY ARPT AROUND NEW YORK. ONCE WE GOT INTO A FAMILIAR AREA WE GOT COMPLACENT. BOTH OF US MISSED THAT FL300 WAS WRONG. SUPPLEMENTAL INFO FROM ACN 492137: WE ALWAYS HAVE THE PNF WORK THE RADIOS. THE PF ALWAYS SETS THE HEADING BUG AND VERIFIES INPUTS TO THE FMS, HOWEVER, THE PNF IS THE SOLE MANIPULATOR OF THE ALT SELECTOR KNOB. THIS FACT POINTS OUT THAT IF THE PNF MAKES AN ERROR IN SELECTION, THE PF MAY NOT CATCH IT. CHK AND BAL IS GONE. ALSO, FOR THIS PARTICULAR CASE IT SHOULD HAVE BEEN OBVIOUS TO US THAT AN ERROR ON OUR PART WAS MADE (BECAUSE OF THE FACT THAT FL300 IS NOT USED).

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.