Misinterp of clearance to reduce speed 260 KTS as descend to FL260.

Attributes
ACN	92448
Time
Date	198808
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : bna
State Reference	TN
Altitude	msl bound lower : 30200 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zme
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude cruise other descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 8 flight time total : 15500 flight time type : 4000
ASRS Report	92448
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Aircraft had just leveled at FL310 (about 1 min) center called and gave '260.' first officer reached and reset cabin pressure and I started descent to FL260. At 30200' center called and said climb to FL310 (or some transmission of this sort). I asked first officer if they had not given us FL260, and he said, 'no,' the '260' was 'slow to 260 KTS.' contributing to the misunderstanding was first officer resetting cabin and the low vol on radio--low to the point that I should have turned vol up. We went back immediately to FL310. Balance of flight was uneventful. The controller made no comment except the climb to FL310. I believe the following were contributing factors: in frequency of flying, I get out of rhythm of things. We had just discussed descending at pilot's discretion, re: when the center gives you an altitude change and doesn't say 'pd,' you start down. The resetting of cabin which is done prior to descent, the low radio vol, the smooth start of descent--the first officer was not aware of me starting down. We were paying attention but were talking of company matters.

Original NASA ASRS Text

Title: MISINTERP OF CLRNC TO REDUCE SPEED 260 KTS AS DESCEND TO FL260.

Narrative: ACFT HAD JUST LEVELED AT FL310 (ABOUT 1 MIN) CENTER CALLED AND GAVE '260.' F/O REACHED AND RESET CABIN PRESSURE AND I STARTED DSCNT TO FL260. AT 30200' CENTER CALLED AND SAID CLB TO FL310 (OR SOME XMISSION OF THIS SORT). I ASKED F/O IF THEY HAD NOT GIVEN US FL260, AND HE SAID, 'NO,' THE '260' WAS 'SLOW TO 260 KTS.' CONTRIBUTING TO THE MISUNDERSTANDING WAS F/O RESETTING CABIN AND THE LOW VOL ON RADIO--LOW TO THE POINT THAT I SHOULD HAVE TURNED VOL UP. WE WENT BACK IMMEDIATELY TO FL310. BALANCE OF FLT WAS UNEVENTFUL. THE CTLR MADE NO COMMENT EXCEPT THE CLB TO FL310. I BELIEVE THE FOLLOWING WERE CONTRIBUTING FACTORS: IN FREQ OF FLYING, I GET OUT OF RHYTHM OF THINGS. WE HAD JUST DISCUSSED DSNDING AT PLT'S DISCRETION, RE: WHEN THE CENTER GIVES YOU AN ALT CHANGE AND DOESN'T SAY 'PD,' YOU START DOWN. THE RESETTING OF CABIN WHICH IS DONE PRIOR TO DSCNT, THE LOW RADIO VOL, THE SMOOTH START OF DSCNT--THE F/O WAS NOT AWARE OF ME STARTING DOWN. WE WERE PAYING ATTN BUT WERE TALKING OF COMPANY MATTERS.

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.