A descending B737-200 flight crew overshoots their assigned altitude of 11000 ft, going to 10000 ft,...

Attributes
ACN	474719
Time
Date	200006
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : mad.vor
State Reference	CT
Altitude	msl bound lower : 10200 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zbw.artcc tower : jxn.tower
Operator	common carrier : air carrier
Make Model Name	B737-200
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	descent : vacating altitude
Route In Use	arrival star : deerparic
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 250 flight time total : 11500 flight time type : 6000
ASRS Report	474714
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : multi engine
Events
Anomaly	altitude deviation : overshoot non adherence : clearance non adherence : published procedure other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued advisory 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:

During descent on dpk 2 arrival into bdl, while descending through approximately 10200 ft on our way to 10000 ft, ZBW inquired about our altitude. We advised we were through 10200 ft going to 10000 ft. Center advised assigned altitude was 11000 ft, and that we should climb back to 11000 ft and switch to bdl approach. There was no aircraft conflict. The first officer and I are still unsure how this happened. The aircraft was on autoplt. The altitude alerter was set for 10000 ft. We both believed we were cleared to 10000 ft. Altitude awareness procedures were not an issue. To my knowledge this crew was flawless in this aspect during the whole trip. My first officer is as good as they get in our company's point and verify altitude procedure. Possibilities: 1) the clearance to descend was given in conjunction with local altimeter setting of 30.11. Perhaps the center controller meant to say 11000 ft (one, one thousand) altimeter 30.11 (three, zero, one, one) but actually said 10000 ft (one, zero thousand). We will never know without pulling the tapes. 2) the clearance to descend was given as '11000 ft' (one, one thousand) 'altimeter 30.11' (three, zero, one, one) and both the first officer and I misunderstood and read back 10000 ft (one, zero thousand) while setting 10000 ft in the altitude alerter. Also, the controller did not catch the error. 3) the clearance to descend was given as '11000 ft, altimeter 30.11.' it was read back correctly, but set incorrectly in the altitude alerter and both the first officer and I pointed to 10000 ft yet said '11000 ft.' we will never (probably) know which of the above happened, however, a few observations: 1) the published 'expect' altitude is 11000 ft. If the assigned altitude was not 11000 ft we could have questioned this. 2) extra care should be taken with 10000 ft (one, zero) and 11000 ft (one, one) clrncs as they have a higher tendency to be issued, heard, read back and set incorrectly.

Original NASA ASRS Text

Title: A DSNDING B737-200 FLC OVERSHOOTS THEIR ASSIGNED ALT OF 11000 FT, GOING TO 10000 FT, 5 NM SW OF MAD, CT.

Narrative: DURING DSCNT ON DPK 2 ARR INTO BDL, WHILE DSNDING THROUGH APPROX 10200 FT ON OUR WAY TO 10000 FT, ZBW INQUIRED ABOUT OUR ALT. WE ADVISED WE WERE THROUGH 10200 FT GOING TO 10000 FT. CTR ADVISED ASSIGNED ALT WAS 11000 FT, AND THAT WE SHOULD CLB BACK TO 11000 FT AND SWITCH TO BDL APCH. THERE WAS NO ACFT CONFLICT. THE FO AND I ARE STILL UNSURE HOW THIS HAPPENED. THE ACFT WAS ON AUTOPLT. THE ALT ALERTER WAS SET FOR 10000 FT. WE BOTH BELIEVED WE WERE CLRED TO 10000 FT. ALT AWARENESS PROCS WERE NOT AN ISSUE. TO MY KNOWLEDGE THIS CREW WAS FLAWLESS IN THIS ASPECT DURING THE WHOLE TRIP. MY FO IS AS GOOD AS THEY GET IN OUR COMPANY'S POINT AND VERIFY ALT PROC. POSSIBILITIES: 1) THE CLRNC TO DSND WAS GIVEN IN CONJUNCTION WITH LCL ALTIMETER SETTING OF 30.11. PERHAPS THE CTR CTLR MEANT TO SAY 11000 FT (ONE, ONE THOUSAND) ALTIMETER 30.11 (THREE, ZERO, ONE, ONE) BUT ACTUALLY SAID 10000 FT (ONE, ZERO THOUSAND). WE WILL NEVER KNOW WITHOUT PULLING THE TAPES. 2) THE CLRNC TO DSND WAS GIVEN AS '11000 FT' (ONE, ONE THOUSAND) 'ALTIMETER 30.11' (THREE, ZERO, ONE, ONE) AND BOTH THE FO AND I MISUNDERSTOOD AND READ BACK 10000 FT (ONE, ZERO THOUSAND) WHILE SETTING 10000 FT IN THE ALT ALERTER. ALSO, THE CTLR DID NOT CATCH THE ERROR. 3) THE CLRNC TO DSND WAS GIVEN AS '11000 FT, ALTIMETER 30.11.' IT WAS READ BACK CORRECTLY, BUT SET INCORRECTLY IN THE ALT ALERTER AND BOTH THE FO AND I POINTED TO 10000 FT YET SAID '11000 FT.' WE WILL NEVER (PROBABLY) KNOW WHICH OF THE ABOVE HAPPENED, HOWEVER, A FEW OBSERVATIONS: 1) THE PUBLISHED 'EXPECT' ALT IS 11000 FT. IF THE ASSIGNED ALT WAS NOT 11000 FT WE COULD HAVE QUESTIONED THIS. 2) EXTRA CARE SHOULD BE TAKEN WITH 10000 FT (ONE, ZERO) AND 11000 FT (ONE, ONE) CLRNCS AS THEY HAVE A HIGHER TENDENCY TO BE ISSUED, HEARD, READ BACK AND SET INCORRECTLY.

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.

A descending B737-200 flight crew overshoots their assigned altitude of 11000 ft, going to 10000 ft, 5 NM southwest of mad, ct.