Pilot deviation caused by misunderstood clearance.

Attributes
ACN	296445
Time
Date	199502
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mwa
State Reference	IL
Altitude	msl bound lower : 28000 msl bound upper : 29000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zkc
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 121
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 80 flight time total : 14000 flight time type : 80
ASRS Report	296445
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

En route from bwi-stl, we had stepped down from FL390 and was at FL280 for approximately 2 mins when ATC asked what our altitude was. I responded 'level FL280' and she then said we should be at FL290. I said that I read back FL280 as our assigned altitude and assumed this was correct since I had not been corrected. She responded that she had not heard that, we were then cleared up to FL290. Communications are critical, why bother to read back a clearance if ATC is not going to listen? ATC was somewhat busy, we were XXX and there was a similar call sign on the frequency.

Original NASA ASRS Text

Title: PLTDEV CAUSED BY MISUNDERSTOOD CLRNC.

Narrative: ENRTE FROM BWI-STL, WE HAD STEPPED DOWN FROM FL390 AND WAS AT FL280 FOR APPROX 2 MINS WHEN ATC ASKED WHAT OUR ALT WAS. I RESPONDED 'LEVEL FL280' AND SHE THEN SAID WE SHOULD BE AT FL290. I SAID THAT I READ BACK FL280 AS OUR ASSIGNED ALT AND ASSUMED THIS WAS CORRECT SINCE I HAD NOT BEEN CORRECTED. SHE RESPONDED THAT SHE HAD NOT HEARD THAT, WE WERE THEN CLRED UP TO FL290. COMS ARE CRITICAL, WHY BOTHER TO READ BACK A CLRNC IF ATC IS NOT GOING TO LISTEN? ATC WAS SOMEWHAT BUSY, WE WERE XXX AND THERE WAS A SIMILAR CALL SIGN ON THE FREQ.

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.