Flight crew of air carrier reportedly descended from assigned altitude without clearance.

Attributes
ACN	102419
Time
Date	198901
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : chs
State Reference	SC
Altitude	msl bound lower : 29000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zjx artcc : ztl
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other cruise other descent other
Route In Use	enroute airway : zjx
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 175 flight time total : 15000 flight time type : 12000
ASRS Report	102419
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude 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:

Captain went to lavatory. During that time ATC cleared the flight from FL330 to FL290. Copilot read back the clearance. During descent ATC asked that the flight expedite to FL290. That clearance was also read back by the copilot. Captain returned during level off. Just prior to this a frequency change was given and acknowledged by copilot. Upon going to this frequency, no contact was established and the flight returned to prior frequency. No response on prior frequency. We established contact with atl center on an area frequency. He gave us a new frequency. The controller on this frequency asked what we were doing at FL290. Said prior controller never gave us a descent clearance not having heard the communication exchange I have no recommendation. However, on leaving the cockpit again, I would have the second officer handle communications for the pilot flying, thus keeping, whenever possible, two people in the communications loop.

Original NASA ASRS Text

Title: FLT CREW OF ACR REPORTEDLY DESCENDED FROM ASSIGNED ALT WITHOUT CLRNC.

Narrative: CAPT WENT TO LAVATORY. DURING THAT TIME ATC CLRED THE FLT FROM FL330 TO FL290. COPLT READ BACK THE CLRNC. DURING DSCNT ATC ASKED THAT THE FLT EXPEDITE TO FL290. THAT CLRNC WAS ALSO READ BACK BY THE COPLT. CAPT RETURNED DURING LEVEL OFF. JUST PRIOR TO THIS A FREQ CHANGE WAS GIVEN AND ACKNOWLEDGED BY COPLT. UPON GOING TO THIS FREQ, NO CONTACT WAS ESTABLISHED AND THE FLT RETURNED TO PRIOR FREQ. NO RESPONSE ON PRIOR FREQ. WE ESTABLISHED CONTACT WITH ATL CENTER ON AN AREA FREQ. HE GAVE US A NEW FREQ. THE CTLR ON THIS FREQ ASKED WHAT WE WERE DOING AT FL290. SAID PRIOR CTLR NEVER GAVE US A DSCNT CLRNC NOT HAVING HEARD THE COM EXCHANGE I HAVE NO RECOMMENDATION. HOWEVER, ON LEAVING THE COCKPIT AGAIN, I WOULD HAVE THE S/O HANDLE COMS FOR THE PLT FLYING, THUS KEEPING, WHENEVER POSSIBLE, TWO PEOPLE IN THE COMS LOOP.

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.