Air carrier crew covers controller transmission with readback and deviates from assigned altitude.

Attributes
ACN	451020
Time
Date	199910
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	intersection : holey
State Reference	PA
Altitude	msl single value : 11000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : intermediate altitude descent : holding
Route In Use	arrival : holding pattern
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : flight engineer
Experience	flight time last 90 days : 250 flight time total : 5500
ASRS Report	451020
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We wre holding at holey intersection at 11000 ft. It was the captain's leg and I was the first officer or monitoring pilot. Another aircraft was holding below at 9000 ft and was told to proceed direct rbv VOR. We were then cleared to descend to 9000 ft while in the hold at holey. As we descended, ATC questioned what we were doing. We repeated our instruction to 'descend to 9000 ft while in the hold at holey.' she came back and said not correct, climb to 11000 ft and go direct to rbv VOR. She then said it was her fault because she did not hear us read back the clearance. We then climbed to 11000 ft and went direct to rbv. The problem started when she instructed us to descend to 9000 ft. Before she was finished with her transmission, I read back 'descend and maintain 9000 ft.' I blocked the last part of the transmission and she did not hear my readback. She took the blame for the problem, however, the lesson to be learned is to wait until ATC is finished with their transmission before you read it back. Remembering that ATC, when busy, is not always going to require a readback of instructions or clrncs, as they should.

Original NASA ASRS Text

Title: ACR CREW COVERS CTLR XMISSION WITH READBACK AND DEVIATES FROM ASSIGNED ALT.

Narrative: WE WRE HOLDING AT HOLEY INTXN AT 11000 FT. IT WAS THE CAPT'S LEG AND I WAS THE FO OR MONITORING PLT. ANOTHER ACFT WAS HOLDING BELOW AT 9000 FT AND WAS TOLD TO PROCEED DIRECT RBV VOR. WE WERE THEN CLRED TO DSND TO 9000 FT WHILE IN THE HOLD AT HOLEY. AS WE DSNDED, ATC QUESTIONED WHAT WE WERE DOING. WE REPEATED OUR INSTRUCTION TO 'DSND TO 9000 FT WHILE IN THE HOLD AT HOLEY.' SHE CAME BACK AND SAID NOT CORRECT, CLB TO 11000 FT AND GO DIRECT TO RBV VOR. SHE THEN SAID IT WAS HER FAULT BECAUSE SHE DID NOT HEAR US READ BACK THE CLRNC. WE THEN CLBED TO 11000 FT AND WENT DIRECT TO RBV. THE PROB STARTED WHEN SHE INSTRUCTED US TO DSND TO 9000 FT. BEFORE SHE WAS FINISHED WITH HER XMISSION, I READ BACK 'DSND AND MAINTAIN 9000 FT.' I BLOCKED THE LAST PART OF THE XMISSION AND SHE DID NOT HEAR MY READBACK. SHE TOOK THE BLAME FOR THE PROB, HOWEVER, THE LESSON TO BE LEARNED IS TO WAIT UNTIL ATC IS FINISHED WITH THEIR XMISSION BEFORE YOU READ IT BACK. REMEMBERING THAT ATC, WHEN BUSY, IS NOT ALWAYS GOING TO REQUIRE A READBACK OF INSTRUCTIONS OR CLRNCS, AS THEY SHOULD.

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.